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    Chemical Composition and Bioactivity of Dissolvable Organic Matter in Biochars
    BIAN RongJun,LIU XiaoYu,ZHENG JuFeng,CHENG Kun,ZHANG XuHui,LI LianQing,PAN GenXing
    Scientia Agricultura Sinica    2022, 55 (11): 2174-2186.   DOI: 10.3864/j.issn.0578-1752.2022.11.008
    Abstract556)   HTML59)    PDF (1094KB)(133)       Save

    Volatile organic components escape from the solid feedstock when biomass pyrolyze, which is re-absorbed onto the surface of biochar in the form of dissolvable organic matter (DOM) following cooling. The condense Biochar DOM has a complex chemical composition, mainly containing small molecular weight organics, polycyclic hydrocarbons rich in functional groups. With high activity of chemical reaction and biological stimulation, the biochar DOM may alter the form and availability of nutrients and pollutants, mediating microbial abundance and community structure, and regulating plant growth and metabolism. These activities and chemical compositions vary with types of biomass feedstock and pyrolysis conditions. The role of biochar DOM in biological regulation is generally recognized as bio-promotion though a few DOM molecules is known of potential toxicity to plants, animals and microbes. In order to reach a differential and valorized utilization, the biochar DOM could be extracted for producing commercial liquid fertilizer. The identification of potential bio-toxic molecules in biochar DOM in relation to feedstock and pyrolysis condition deserve further studies, which is fundamental for optimizing production of biochar and biochar-derived products, and minimizing environmental risks following land allocation.

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    PSORA: A Strategy Based on High-Throughput Sequence for Analysis of T-DNA Insertion Sites
    MA XueMeng,YU ChengMin,SAI XiaoLing,LIU Zhen,SANG HaiYang,CUI BaiMing
    Scientia Agricultura Sinica    2022, 55 (15): 2875-2882.   DOI: 10.3864/j.issn.0578-1752.2022.15.001
    Abstract442)   HTML67)    PDF (670KB)(93)       Save

    【Objective】The purpose of this study was to establish a simple and efficient approach for identifying all T-DNA insertion sites. 【Method】A T-DNA insertion sites analysis approach based on high-throughput sequence technologies was developed, called PSORA: Parallel sequencing of one round amplicons. The process involves high-throughput amplicon sequencing of a round of thermal asymmetric PCR (TAIL-PCR) and bioinformatics analysis of T-DNA insertion sites, which reduces concerns about the specificity of TAIL-PCR. In PSORA, only two primers are required, a degenerate primer and a T-DNA specific primer. A 6-nt Barcode was designed at the 5’ end of the specific primers for labeling different transgenic events. All five transgenic events (L1, L6, L9, L15 and L19) of tobacco used in this study were produced via Agrobacterium mediated transformation with plasmids pBI121. In addition, the results of PSORA are confirmed by standard PCR. 【Result】The T-DNA insertion sites of five transgenic events were analyzed by PSORA. The results showed that L6 contained two insertion sites (36 316 bp on NW_015801367 and 42 202 bp on NW_015950898), the lines of L9, L15 and L19 each contained one insertion site (The insertion site of L9 was located at 235 969 bp on NW_015943682. The insertion site of L15 was located at 60 529 bp on NW_015802951 and the insertion site of L19 was located at 12 188 bp on NW_015863435), but the insertion site of L1 could not be detected. PCR was performed to validate the results from bioinformatics analysis, transgenic events with different insertion sites were used as negative controls for each other, and the wild type (WT) was used as a blank control. The results showed that specific amplification consistent with expectations was obtained in each transgenic event. The effectiveness of PSORA was successfully confirmed. 【Conclusion】PSORA is an effective strategy to analyze T-DNA insertion sites. PSORA can parse the comprehensive molecular characteristics of all T-DNA insertion events simultaneously, making it simpler and faster than the traditional methods of genome walking.

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    Research Advances of Bradyrhizobia and Its Symbiotic Mechanisms with Peanut
    WU Yue,SUI XinHua,DAI LiangXiang,ZHENG YongMei,ZHANG ZhiMeng,TIAN YunYun,YU TianYi,SUN XueWu,SUN QiQi,MA DengChao,WU ZhengFeng
    Scientia Agricultura Sinica    2022, 55 (8): 1518-1528.   DOI: 10.3864/j.issn.0578-1752.2022.08.004
    Abstract441)   HTML55)    PDF (533KB)(166)       Save

    Nitrogen is one of the essential elements for plant growth, which is obtained by legumes through symbiotic nitrogen fixation with rhizobia. The establishment of symbiotic relationship includes nodulation and nitrogen fixation, involving complex regulatory mechanisms, which is also significantly affected by environmental factors. Symbiosis between peanut and bradyrhizobia is essential for peanut growth and production, but contains many specific and unknown symbiotic mechanisms. In this review, symbiosis between peanut bradyrhizobia and peanut was reviewed, including: (1) Diversity and genomic functions of peanut bradyrhizobia; (2) Symbiotic mechanisms between peanut and bradyrhizobia: rhizobial crack infection and symbiotic signal exchange with peanut, peanut nodulation, nitrogen fixation, and nodule number regulation mechanisms; (3) Effects of environmental factors (soil nitrogen, pH, temperature and water content) on peanut nodulation, nitrogen fixation and yield. This review pointed out current problems in peanut bradyrhizobia, symbiosis between peanut and bradyrhizobia, and peanut field application, including few studies on genome functions of peanut bradyrhizobia, unknown interaction mechanisms between bradyrhizobia and peanut in details, as well as, poor utilization rate of peanut bradyrhizobia in the field, etc. Based on this analysis, the future researches should focus on genome omics analysis and gene functional analysis of peanut bradyrhizobia; signal communication pathways, nodule number regulation mechanisms, nutrient exchange systems between bradyrhizobia and peanut; rational application systems of nitrogen fertilizer that match with nodule nitrogen fixation rules, and obtain new peanut bradyrhizobia agents for peanut planting through synthetic biology. This article provided the theoretical basis for further understanding the symbiotic mechanisms of legumes and rhizobia, improving nodulation and nitrogen fixation efficiency of legume crops, reducing chemical nitrogen application, and improving agricultural ecological environment.

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    Genome-Wide Association Study of Cold Tolerance at the Germination Stage of Rice
    PANG HongBo, CHENG Lu, YU MingLan, CHEN Qiang, LI YueYing, WU LongKun, WANG Ze, PAN XiaoWu, ZHENG XiaoMing
    Scientia Agricultura Sinica    2022, 55 (21): 4091-4103.   DOI: 10.3864/j.issn.0578-1752.2022.21.001
    Abstract416)   HTML96)    PDF (3604KB)(268)       Save

    【Objective】Rice is an important food crop, and its growth and development are most vulnerable at the germination stage. Under cold stress, direct-seeded rice exhibited significantly reduced germination rates (GRs) and yield compared with normally grown plants. Thus, a better understanding of genetic mechanisms regulating cold tolerance will enable to develop rice varieties with improved tolerance during germination. 【Method】238 representative rice germplasm resources from 14 countries worldwide were tested in phenotypic identification in Shenyang in 2021 and 2022; the low-temperature germination rate and relative low-temperature germination rate (LTGR and relative LTGR; 1-10 days under 15℃) were evaluated in an artificial climate incubator, and a 5-10 day LTGR histogram was constructed using R. The day suitable for GWAS was determined by phenotypic variation (Hill) and a mixed linear model combining LTGR and relative LTGR phenotype data with resequencing data. 【Result】LTGR histogram and phenotypic variation showed optimal GR on day 8 (Hill=0.84), i.e., it was higher than on other days (Hill=0.48-0.83), which could be used for GWAS. The principal component analysis results divided all germplasms into five groups—indica, aus, temperate japonica, tropical japonica, and aromatic. GWAS analysis of two indicators detected three identical significant single nucleotide polymorphisms (SNPs) related to cold tolerance in rice at the germination stage. These were located on chromosome 4, which could explain 11.9%-25.4% of the phenotype. In addition, 24 candidate genes were screened in the 50-kb region upstream and downstream of these three SNPs. Further linkage disequilibrium analysis and haplotype analysis were carried out and highly significant differences were found between different haplotypes of the LOC_Os04g24840 and LOC_Os04g25140 genes for cold tolerance. LOC_Os04g24840 was divided into five haplotypes by the coding region SNP, and Hap_3 was significantly more cold tolerant than Hap_1; LOC_Os04g25140 was divided into 18 haplotypes by the coding region SNP and the amino acid variation (S>L) at 77 bp was different in japonica and indica rice. These results showed that the genes encoding glycosyltransferases (LOC_Os04g24840) and F-box protein (LOC_Os04g25140) might be closely related to cold tolerance in rice.【Conclusion】 A total of three SNP loci were detected in 238 rice germplasm resources, and two candidate genes were screened for their association with cold tolerance during germination in rice.

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    Research Progress of Nitrogen Efficiency Related Genes in Rice
    SANG ShiFei,CAO MengYu,WANG YaNan,WANG JunYi,SUN XiaoHan,ZHANG WenLing,JI ShengDong
    Scientia Agricultura Sinica    2022, 55 (8): 1479-1491.   DOI: 10.3864/j.issn.0578-1752.2022.08.001
    Abstract401)   HTML82)    PDF (904KB)(283)       Save

    Over the last few years, China government has put forward a strategy to achieve the goal of “zero growth of chemical fertilizer”. It is particularly important to reduce the input of nitrogen fertilizer in agricultural production and enhance the nitrogen use efficiency in crops. Nitrogen is mostly absorbed from the soil by plant roots in the form of nitrate nitrogen (NO3-) and ammonium nitrogen (NH4-). It is transported from roots in plants to synthesize essential life substances, such as amino acids and nucleotides. Nitrogen is used as a basic element for crop growth and yield formation. However, excessive application of nitrogen fertilizer destroys the physical and chemical properties of the soil, causes undesirable changes to soil salinization, and pollutes the ecological environment, and pollutes the ecological environment. By reducing the quantity of nitrogen fertilizer, will destabilize the yield potential of field crops including rice and wheat which is being used as a staple food in China. It can threaten food security of the country. To improve the nitrogen use efficiency (NUE) and stabilize the food security, mining nitrogen-efficient genes, such as NRT1.1B, OsGRF4 etc., genetic improvement of current existing varieties through molecular design breeding will help to cultivate new nitrogen efficiently rice lines. Tapping the productive potential of current rice varieties will improve the level of sustainable agricultural development in our country. In this article, based on the nitrogen-efficient genes excavated in the current rice research, this article reviews the PTR (polypeptide transporter) family, NRT (nitrate transporter) family, AMT family (ammonium transporter family), NLP family and other types of rice nitrogen-efficient genes. The future prospects of gene utilization have been prospected. Based on the nitrogen-efficient genes excavated in the current rice research, they are divided into four categories: NRT/PTR, AMT (ammonium transporter), NLP and other types, and summarize their functions and characteristics, and analysis the utilization prospect and existing problems of nitrogen-efficient genes with potential breeding value.

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    Cloning and Drought Resistance Analysis of Transcription Factor GhMYB108 in Gossypium hirsutum
    LIU RuiDa, GE ChangWei, WANG MinXuan, SHEN YanHui, LI PengZhen, CUI ZiQian, LIU RuiHua, SHEN Qian, ZHANG SiPing, LIU ShaoDong, MA HuiJuan, CHEN Jing, ZHANG GuiYin, PANG ChaoYou
    Scientia Agricultura Sinica    2022, 55 (10): 1877-1890.   DOI: 10.3864/j.issn.0578-1752.2022.10.001
    Abstract399)   HTML77)    PDF (7239KB)(326)       Save

    【Objective】As one of the largest transcription factor families in plants, MYB genes play an important role in resisting stress. The MYB transcription factor GhMYB108 was cloned and analyzed to verify its role in drought stress response, which laid a foundation for further study on the molecular mechanism of GhMYB108 regulating drought tolerance in G. hirsutum.【Method】Through the analysis of unpublished drought transcriptome data, GhMYB108 was identified to drought response. The target gene was amplified from the root cDNA by polymerase chain reaction (PCR). Through bioinformatics analysis of gene structure characteristics, the sequence information and phylogenetic relationship of these genes were predicted. The obtained gene promoter sequences were analyzed by Plant Care website. The genes expression characteristics under different stress conditions were analyzed using Real time fluorescence quantitative PCR (qRT-PCR). The location of GhMYB108 protein was determined by subcellular localization. The transcriptional activity was tested in yeast cell; The GhMYB108 gene was silenced using Virus induced gene silencing (VIGS), and the gene silencing efficiency was detected by qRT-PCR. The phenotypic changes before and after drought treatment were observed and the survival rate was counted. The relevant physiological and biochemical indexes were measured by Solarbio Kit; The relationship between GhMYB108 and ABA was analyzed by spraying ABA and Fluridone on cotton leaves.【Result】GhMYB108 (Gh_A10G1563) was cloned from G. hirsutum, with 879 bp length and 292 amino acids. Its protein relative molecular weight and isoelectric point is 33.288 kD and 6.037, respectively. Multiple sequence alignment and conserved domain analysis showed that GhMYB108 contains two highly conserved MYB binding domains, which belongs to a typical R2R3 MYB transcription factor. Phylogenetic analysis of different species showed that GhMYB108 was highly homology with ATMYB108, ATMYB78 and ATMYB2, belonging to the same subfamily. Previous studies found that ATMYB108, ATMYB78 and ATMYB2 were related to drought and ABA signaling pathway. GhMYB108 located in the nucleus and had transcriptional activation activity. The expression level of GhMYB108 was the highest in roots and the lowest in stems, and was induced by abiotic stresses including natural drought, 18% PEG 6000 simulated drought, salt stress and low temperature. The GhMYB108 silenced plants showed a critical phenotype under natural drought conditions. Compared with the control, the silenced plants showed more serious wilting and decreased survival rate. Some physiological and biochemical indexes also changed significantly, such as accelerated leaf water loss rate, increased malondialdehyde content, decreased leaf relative water content and proline content, and decreased CAT and POD activities. Through DAB and NBT staining, the hydrogen peroxide (H2O2) and superoxide anion (O2-) were significantly accumulated in plants. By spraying the hormone ABA or Fluridone on cotton leaves, we found that GhMYB108 could be positively regulated by ABA signal.【Conclusion】GhMYB108 positively regulates cotton drought resistance and is positively regulated by ABA signal.

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    Genome-Wide Association Study of Ear Related Traits in Maize Hybrids
    LI Ting,DONG Yuan,ZHANG Jun,FENG ZhiQian,WANG YaPeng,HAO YinChuan,ZHANG XingHua,XUE JiQuan,XU ShuTu
    Scientia Agricultura Sinica    2022, 55 (13): 2485-2499.   DOI: 10.3864/j.issn.0578-1752.2022.13.001
    Abstract391)   HTML72)    PDF (4472KB)(249)       Save

    【Objective】Ear traits are important components of grain yield in maize. Dissecting their genetic basis and mining significant SNPs using genome-wide association study (GWAS) can provide references for cloning functional genes and breeding high-yield maize varieties. 【Method】A total of 115 superior inbred lines from Shaan A group and Shaan B group, as well as four domestic backbone lines were selected as parents. Based on NCⅡ genetic design, an association population consisting of 442 hybrids was constructed, which was planted in two different environments to collect phenotype data of ear traits. Meanwhile, all parental lines were sequenced by the tunable genotyping by sequencing (tGBS) protocols. According to the genotype of inbred lines, altogether 19 461 high-quality SNPs were inferred in the association population. Then, GWAS was performed using 19 461 SNPs and phenotype data by three models including additive, dominance and epistasis, respectively. Combining with the transcriptome data of maize ear related tissues in the public database and the annotation information of genes, candidate genes were predicted. 【Result】Phenotypic data analysis showed that eight ear traits followed a continuous distribution, and there were 3.78%-45.25% of phenotypic variation. Analysis of variance indicated that environment and genotype effects reached an extremely significant level (P<0.001), and the range of broad-sense heritability was from 54.15% to 68.89%. And there were significantly positive or negative correlations among ear traits of hybrids. In total, 16, 3, 79 significant SNPs/pairs were identified under additive, dominant, and epistatic models, respectively. The significant loci detected by the three models cumulatively explained 38.21%-60.69% of the phenotypic variation of each trait. The cumulative phenotypic variation of significant SNP detected by additive model and epistatic model was 0.00-41.26% and 15.18%-45.36%, respectively. Effect analysis of significant SNPs identified by additive and dominant models showed most SNPs with additive or partial dominance effects, and only two with over-dominance effects. Further, only seven single-SNPs and five interaction pairs explained more than 5% of the phenotypic variation, and 17 candidate genes were predicted based on the SNP locations and gene expression information. 【Conclusion】Ear traits of maize hybrids were mainly affected by additive and epistasis effects, but less by dominance effects. Multiple SNPs identified by additive and dominant models showed additive and partially dominance effects, and aggregating favorable alleles of these SNPs could improve the target traits.

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    Genome-Wide Association Analysis of Yield and Combining Ability Based on Maize Hybrid Population
    LI ZhouShuai,DONG Yuan,LI Ting,FENG ZhiQian,DUAN YingXin,YANG MingXian,XU ShuTu,ZHANG XingHua,XUE JiQuan
    Scientia Agricultura Sinica    2022, 55 (9): 1695-1709.   DOI: 10.3864/j.issn.0578-1752.2022.09.001
    Abstract384)   HTML84)    PDF (3116KB)(214)       Save

    【Objective】By analyzing the yield of the hybrids from the inbred lines bred from the Shaan A and Shaan B group, the combining ability of the inbred lines were evaluated, genome-wide association analysis, and mining associated loci for yield and its combining ability conducted. It will provide references for improving maize inbred lines selected from Shaan A group and Shaan B group and applying them in varieties breeding. 【Method】Based on NCⅡ genetic design, 85 excellent inbred lines from Shaan A group and Shaan B group were used to construct a hybrid population containing 246 F1. Then, the yield of the hybrid population was tested in three environments to evaluate their general combining ability (GCA) and special combining ability (SCA). Using the 6H90K maize array to detect the parental genotypes, 63 879 high-quality SNPs were obtained, which were used to analyze the genetic characteristics of parental lines. According to the parental genotypes, 55 951 high-quality SNPs were inferred in the hybrid population for genome-wide association analysis of hybrid yield, GCA, and SCA using additive model and non-additive model. Meanwhile, candidate genes around the significant SNPs were screened and annotated based on the maize B73 reference genome.【Result】The yield in the three environments accorded to the normal distribution with wide variation, the broad-sense heritability of yield was 59.04%, and the environmental effect was significant. There was significant positive correlation between hybrid yield and combining ability, and the correlation between hybrid yield and SCA (r=0.95) was higher than that between hybrid yield and GCA (r=0.62). The genetic characteristic of Shaan A group and Shaan B group was different, and inbred lines from Shaan A group have higher general combining ability. Totally, five, seven and nine significant SNPs were detected (-log10(P)>3.86) for GCA, hybrid yield and SCA, respectively. Among them, four SNPs were co-located in hybrid yield and SCA. Ultimately, 17 associated SNPs were anchored. Dominant allele analysis of different trait-associated loci showed that four GCA-associated SNPs were controlled by additive effects, and the F1 BLUE-associated loci could be divided into 4 types mainly by the dominant effect, and the heterozygous genotype is the favorite allele or sub-optimal allele for yield in F1. Through functional annotation, the candidate genes were specifically expressed in maize growth and kernel establishment, for example, GRMZM2G165828 and GRMZM2G057557 were related to maize kernel development. 【Conclusion】Based on this study, we consider that GCA and SCA jointly affect the yield of hybrids, and the effect of SCA is greater. Moreover, GCA and SCA may have different genetic basis, and GCA can be increased with the accumulation of favorable alleles. Using the genome-wide association analysis in the F1 hybrid population can carry out genetic analysis related to combining ability, mine the genetic loci related to yield and combining ability, and accelerated the application of the associated loci in molecular breeding.

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    Commercialization Status and Existing Problems of RNA Biopesticides
    GUAN RuoBing,LI HaiChao,MIAO XueXia
    Scientia Agricultura Sinica    2022, 55 (15): 2949-2960.   DOI: 10.3864/j.issn.0578-1752.2022.15.007
    Abstract380)   HTML45)    PDF (482KB)(142)       Save

    RNA biopesticides use the principle of RNA interference (RNAi) to inhibit the expression of important genes in target organisms, causing the developmental retardation or death of harmful organisms, thereby achieving the purpose of pest control. The technology does not alter the genome of pests and cause adverse effects on the ecosystem. RNA biopesticides are called “the third revolution in the history of pesticides” because they have the advantages of precision, high efficiency, green and pollution-free, etc. In recent years, with the approval of Bayer’s insect-resistant transgenic maize MON87411 which expressing insect dsRNA, major traditional agrochemical companies have invested a lot of manpower and material resources in layout and product development. In addition, it has also attracted the attention of the capital market, and large numbers of companies based on RNAi technology for pest control have emerged, which has greatly accelerated the industrialization of RNA biopesticides. With the rapid development of RNA biopesticides, it will be bound to change the global pesticide market pattern, which is undoubtedly a new challenge. Although the R&D program in this field started early and the starting point is relatively high in our country, most of the research mainly focuses on basic theories, and the application development is relatively weak, which has lagged far behind the international counterparts. Compared with traditional pesticides, RNA biopesticides have their own unique features in both mechanism and application development. It is urgent to improve the corresponding laws and regulations to supervise and guide production, promote the rapid development of RNA biopesticides in our country, and reduce the risk of international pesticide giants forming a technological monopoly in this field. Based on this, this paper systematically summarized the current domestic and foreign R&D status, commercialization, and future development trends of RNA biopesticides, as well as the regulations and policies related to RNA biopesticides in Europe, the United States and other countries. In addition, the paper also pointed out some urgent problems in the progress of R&D and industrialization of RNA biopesticides, hoping to provide a useful reference for the development and supervision of RNA biopesticides in China.

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    Mining of Genetic Locus of Maize Stay-Green Related Traits Under Multi-Environments
    CHANG LiGuo,HE KunHui,LIU JianChao
    Scientia Agricultura Sinica    2022, 55 (16): 3071-3081.   DOI: 10.3864/j.issn.0578-1752.2022.16.001
    Abstract372)   HTML250)    PDF (2062KB)(365)       Save

    【Objective】 Functional stay-green is generally considered a desirable trait in major crop varieties including maize. Finding new loci and candidate genes related to stay-green, and providing new theoretical basis for the genetic research on stay-green. 【Method】Using 150 recombinant inbred lines (RIL) populations derived from the cross between Xu 178 and K12, QTL mapping of three stay-green related traits (visual stay green (VSG), green leaf number at silking stage (GLNS) and green leaf number at mature stage (GLNM) were performed by the composite interval mapping(CIM)method of Windows QTL Cartographer V2.5. Besides, an association population, which composed of 139 natural materials genotyped with 50790 high-quality SNP markers, was used to dissect genetic locus of three traits by genome-wide association study (GWAS) based on the mixed linear model MLM). 【Result】Based on CIM, three traits (GLNM, GLNS and VSG)were mapped using phenotypic values in a single environment and best linear unbiased prediction (BLUP) value. A total of 37 QTLs were detected on all chromosomes except Chromosome 10, and the LOD score ranged from 2.58-11.36, with a phenotypic variation contribution rate of 4.34%-22.40%. Among them, 14, 12 and 11 loci were detected for GLNM, GLNS and VSG traits, respectively. Four of the QTLs, qGLNS2-1, qVSG1-1, qVSG1-2 and qVSG7-1, were genetically stable and were detected simultaneously in three or more different single environments. GWAS was performed on three stay-green related traits using MLM, and a total of 44 significant SNPs above the threshold line were detected. According to the physical position of SNP markers in the B73 reference genome, a total of 15 SNP were found to fall into the QTL interval mapped by linkage analysis. 【Conclusion】Combined with the results of QTL mapping and genome-wide association study, a total of 4 genetically stable colocalization genetic regions were detected (the corresponding physical position intervals on the B73 reference genome version 4 are 6.2-8.2 Mb on chromosome 1, 209.1-221.4 Mb on chromosome 2, 96.8-102.1 Mb on chromosome 6, and 4.9-11.4 Mb on chromosome 7), and four important candidate genes (Zm00001d006119, Zm00001d018975, Zm00001d006535 and Zm00001d036763) related to photosynthesis and stress response were mined.

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    Genome-Wide Association Study of Yield Component Traits in Upland Cotton (Gossypium hirsutum L.)
    WANG Juan, MA XiaoMei, ZHOU XiaoFeng, WANG Xin, TIAN Qin, LI ChengQi, DONG ChengGuang
    Scientia Agricultura Sinica    2022, 55 (12): 2265-2277.   DOI: 10.3864/j.issn.0578-1752.2022.12.001
    Abstract356)   HTML90)    PDF (6687KB)(206)       Save

    【Objective】The loci, elite alleles and candidate genes associated with yield component traits, such as boll weight, lint percentage, number of bolls per plant and seed index, were explored using a genome-wide association analysis (GWAS), which provided a theoretical reference for the molecular breeding of cotton yield.【Method】The GWAS based on a mixed linear model was performed on 408 upland cotton accessions grown in six different environments using the Cotton SNP 80K chip for the four yield component traits, and the significant SNP loci (SNPs) and elite allele were also detected. Finally, on the basis of the gene expression levels of the transcriptome, candidate genes related to the target traits were mined within a 1 Mb genome range of the flanking sequences of the significant SNPs. 【Result】The four yield component traits showed wide phenotypic variations in different environments, with the maximum coefficient of variation for number of bolls per plant being 16.67%-22.66%. The heritability of each trait was between 48.4% and 92.2%. The correlations among traits were significant or highly significant, except between boll weight and lint percentage. A total of 23 significant SNPs distributed in seven different genomic regions associated with the four traits were identified across the 408 cotton accessions in the BLUP. The numbers of loci associated with boll weight, lint percentage, number of bolls per plant and seed index were 5, 1, 9 and 8, respectively, and three loci (TM21094, TM21102, and TM57382) were associated with multiple target traits simultaneously. Seven elite allele types, TM21099(TT), TM57382(GG), TM78920(CC), TM53448(TT), TM59015(AA), TM43412(GG) and TM69770(AA), were identified. A total of 158 candidate genes potentially related to yield formation were selected through an analysis of gene expression patterns in RNA-Seq data. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses indicated that the functions and metabolic pathways of most genes were varied.【Conclusion】In this study, 23 significant SNPs associated with four yield component traits were identified across 408 cotton accessions, and 158 candidate genes were predicted using RNA-Seq.

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    Effects of Different Nitrogen Application Levels on Photosynthetic Characteristics, Nitrogen Use Efficiency and Yield of Spring Maize in Sichuan Province
    XIONG WeiYi,XU KaiWei,LIU MingPeng,XIAO Hua,PEI LiZhen,PENG DanDan,CHEN YuanXue
    Scientia Agricultura Sinica    2022, 55 (9): 1735-1748.   DOI: 10.3864/j.issn.0578-1752.2022.09.004
    Abstract324)   HTML0)    PDF (670KB)(229)       Save

    【Objective】 In order to clarify the photosynthetic mechanism affecting the yield formation of spring maize under different nitrogen application levels, the effects of different nitrogen application levels on nitrogen use efficiency and soil nitrogen surplus were analyzed, so as to provide the theoretical reference for rational application of nitrogen fertilizer and promoting high yield and high efficiency of spring maize.【Method】Using the maize of variety Zhongyu 3 as experimental material, the field experiments were carried out in 2019 and 2020 at the long-term fertilizer effect experimental site of Ya’an Experimental Farm of Sichuan Agricultural University. Nitrogen supply included five levels, such as 0 (no nitrogen application), 90 (low nitrogen), 180 (appropriate amount of nitrogen), 270 (farmers’ habitual nitrogen application), and 360 kg·hm-2 (high nitrogen), which were marked as N0, N1, N2, N3, and N4, respectively. The leaf area was measured at jointing period, silking period and grain-filling period, and the leaf area index and leaf area duration were calculated, respectively. The photosynthetic parameters, such as net photosynthetic rate of ear leaves were measured at grain-filling period, and chlorophyll content was measured at silking period and grain-filling period. The dry matter accumulation of aboveground population was measured at silking period, grain-filling period, and harvest period, the yield was measured at harvest, the nitrogen content of each part was analyzed, and the soil nitrogen surplus, nitrogen use efficiency of spring maize and economic benefit of nitrogen application were calculated.【Result】(1) The spring maize yield increased first and then remained flat with the increase of nitrogen application levels. In 2019 and 2020, the yield under N2 treatment was the highest, with an average of 9 746 kg·hm-2, which was 179% and 28.7% higher than that of N0 and N1 treatments (P<0.05), respectively, but there was no significant difference among N2, N3, and N4 treatments. 2-year yield was fitted by linear + platform fitting, the platform nitrogen application level was 134.8 kg·hm-2, the platform yield was 9 604 kg·hm-2, and the output-input ratio of platform nitrogen fertilizer (134.8 kg·hm-2) was the highest (12.6). (2) Compared with no nitrogen application, the appropriate amount of nitrogen application (N2) significantly increased chlorophyll content, net photosynthetic rate, stomatal conductance, transpiration rate of ear leaves, leaf area index and leaf area duration. However, with the increase of nitrogen fertilizer application, there was no significant difference or even decreased significantly in the above indexes. (3) Combined with the correlation analysis and partial least square analysis of photosynthetic characteristics and harvest yield, the yield was significant positively correlated with leaf area duration, net photosynthetic rate, stomatal conductance, transpiration rate, leaf area index, chlorophyll a+b of spring maize (P<0.01), and the main factor affecting spring maize yield was chlorophyll a+b. (4) During the harvest period, the grain nitrogen accumulation and total aboveground nitrogen accumulation increased significantly with the increase of nitrogen application level, and increased slightly or basically flat after N2 treatment (more than 180 kg·hm-2) in the two years. The fitting results showed that the nitrogen application level was 139 kg·hm-2 when the soil nitrogen surplus was 0 kg·hm-2; The nitrogen apparent recovery efficiency of spring maize under N2 treatment was the highest in the two years, with an average of 73.7%, which was 10.8% higher than that under N1 treatment (P<0.05), the nitrogen apparent recovery efficiency decreased significantly with the continuous application of nitrogen fertilizer. Compared with N2 treatment, the nitrogen apparent recovery efficiency of N3 and N4 treatments decreased by 32.9% and 48.1%, respectively (P<0.05).【Conclusion】The proper amount of nitrogen application could obviously improve the photosynthetic performance of spring maize leaves, delay the degradation of total chlorophyll in ear leaves, prolong the duration of photosynthesis, and optimize the role among total chlorophyll, leaf area index and leaf area duration in the yield formation of spring maize. At the same time, the proper amount of nitrogen application could significantly increase the dry matter accumulation of aboveground population and grain yield, promote the absorption and accumulation of nitrogen to maize, reduce nitrogen residue in soil, and improve the nitrogen apparent recovery efficiency. Considering the factors such as yield, economic benefit of fertilization, apparent nitrogen use efficiency and nitrogen surplus, the nitrogen input of 139-180 kg·hm-2 could maintain the goal of high yield and high efficiency of spring maize in the experimental area (Ya’an, Sichuan).

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    Accurate Identification and Comprehensive Evaluation of Panicle Phenotypic Traits of Landraces and Cultivars of Sorghum bicolor (L.) Moench in China
    XU Xiao,REN GenZeng,ZHAO XinRui,CHANG JinHua,CUI JiangHui
    Scientia Agricultura Sinica    2022, 55 (11): 2092-2108.   DOI: 10.3864/j.issn.0578-1752.2022.11.002
    Abstract317)   HTML46)    PDF (4958KB)(169)       Save

    【Objective】 Through the research on the phenotypic diversity and genetic variation of the sorghum germplasm resources in the panicle, we will screen for superior sorghum germplasm, enrich the genetic information of sorghum panicle-related traits, and provide a reference for the conservation and efficient use of existing germplasm resources and the selection and breeding of new varieties.【Method】 Using 320 sorghum accessions from different parts of China as test materials, we accurately identified 12 panicle traits (grain length, grain width, thousand-grain weight, grain hardness, grain density, corneous endosperm rate, kernel weight per panicle, main panicle length, panicle neck length, panicle neck diameter, primary branches length, primary branches number) in two different ecological environments. A comprehensive evaluation of sorghum germplasm resources using correlation analysis, principal component analysis, cluster analysis, and other methods. We screened elite sorghum germplasms with different outstanding characteristics according to the comprehensive evaluation value F and target traits. 【Result】 The frequency distribution of each quantitative trait showed a trend of high in the middle and low on both sides. The two-year frequency distribution and curve trend of grain hardness, kernel weight per panicle and grain density, and corneous endosperm rate were similar at the Baoding and Jinzhong test sites. Most of the traits only showed normal distribution in one year or a single location. Except for the main panicle length and number of primary branches, the other traits differed between the two test sites in the same year. The mean diversity index (H') distribution of the 12 panicle traits ranged from 1.72 to 2.11, among which the average diversity index of grain hardness was the highest, and the average diversity index of primary branches length was the lowest. The coefficients of variation of grain hardness, corneous endosperm rate, kernel weight per panicle, primary branches length, and the number of primary branches were all higher than 30.00%. The cumulative contribution rate of the extracted four principal components was 65.39%. Cluster analysis classified the 320 accessions into three groups, class I can be used as the germplasm for screening process (broom) sorghum; class II is suitable for selecting excellent germplasm for grain (brewing) sorghum; class III was the germplasm with poor panicle traits. We screen 29 superior germplasm with outstanding characteristics according to the comprehensive score value F and target traits. 【Conclusion】 The variability of sorghum germplasm resources in panicle traits was rich and diverse; the coefficient of variation of corneous endosperm rate and primary branches length was high; grain length, grain width, grain hardness, grain density, and kernel weight per panicle were significantly affected by environmental conditions. We screened 29 superior germplasm.

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    Effects of Nitrogen-Reducing Side Deep Application of Liquid Fertilizer at Tillering Stage on Yield and Nitrogen Utilization of Fragrant Rice
    GUI RunFei,WANG ZaiMan,PAN ShengGang,ZHANG MingHua,TANG XiangRu,MO ZhaoWen
    Scientia Agricultura Sinica    2022, 55 (8): 1529-1545.   DOI: 10.3864/j.issn.0578-1752.2022.08.005
    Abstract315)   HTML42)    PDF (946KB)(111)       Save

    【Objective】 The effects of nitrogen-reduced side depth application of liquid fertilizer at tillering stage and conventional total application of solid fertilizer on nitrogen uptake and utilization, dry matter accumulation and physiological nitrogen metabolism in key growth stages of fragrant rice and its relationship with yield formation of fragrant rice were investigated, so as to provide the theoretical basis and guidance for mechanized side deep application of liquid fertilizer at tillering stage in south China fragrant rice growing region in the future.【Method】 Field experiments were conducted for two consecutive years from 2019 to 2020, two popular fragrant rice cultivars with large planting area in South China, including Yuxiangyouzhan and Xiangyaxiangzhan, were used as the test materials, and a randomized complete block design was adopted. Four treatments were set up, including no fertilization during rice growth season (T1), total fertilization of solid fertilizer (T2, total nitrogen application rate of 150 kg N·hm-2), side depth application of liquid fertilizer with 10% nitrogen reduction at tillering stage (T3), and side depth application of liquid fertilizer with 20% nitrogen reduction at tillering stage (T4). The effects of different fertilization treatments on yield and its components, nitrogen absorption and utilization, dry matter accumulation and physiological nitrogen metabolism of fragrant rice were analyzed.【Result】 (1) In the two-year field experiments, the yield of both fragrant rice cultivars under T3 treatment was the highest, which was significantly higher than that under T1 treatment. Compared with T2 treatment, the grain yield of Yuxiangyouzhan in 2019 and 2020 under T3 treatment was increased by 1.84% and 15.20%, respectively; the grain yield of Xiangyaxiangzhan in 2019 and 2020 under T3 treatment was increased by 0.65% and 3.71%, respectively. The grain yield increment observed under T3 treatment was mainly related to the highest effective panicle. (2) In the two-year field experiments, the total dry matter accumulation, leaf area index, and total nitrogen accumulation of the two fragrant cultivars at panicle initiation stage and heading stage were generally the highest under T2 treatment, while no significant difference was observed between T3 treatment and T2 treatment. However, the total dry matter accumulation, leaf area index, and total nitrogen accumulation under T3 treatment were the highest for the two fragrant rice cultivars. Compared with T2 treatment, T3 treatment increased total dry matter accumulation, leaf area index, and total nitrogen accumulation of Yuxiangyouzhan by 25.14%, 26.57%, and 21.31% in 2019, respectively, and in 2020 the corresponding increases were 5.83%, 21.80%, and 46.47%, respectively. Compared with T2 treatment, the total dry matter accumulation, leaf area index, and total nitrogen accumulation under T3 treatment for Xiangyaxiangzhan were increased by 19.95%, 3.73%, and 13.41% in 2019, respectively, and in 2020 the corresponding increases were 21.17%, 1.78%, and 14.37%, respectively. In addition, the nitrogen recovery efficiency and nitrogen agronomic efficiency of the two fragrant rice cultivars were also the highest under T3 treatment. (3) At the panicle initiation stage and heading stage, T2 treatment showed higher in the activities of nitrogen metabolism-related enzymes in leaf of the two fragrant rice cultivars as compared with other fertilization treatments, and T3 treatment was observed with the highest activities of nitrogen metabolism-related enzymes in leaf of the two fragrant rice cultivars at maturity stage. 【Conclusion】 The two-year of field experiments showed that, compared with the total fertilization of solid fertilizer treatment, the side depth application of liquid fertilizer with 10% nitrogen reduction at tillering stage treatment could increase the yield of fragrant rice by ensuring the early growth, increasing total dry matter accumulation, leaf area index, nitrogen utilization and nitrogen metabolism-related enzymes activities during the late growth stage while reducing the application rate of nitrogen fertilizer.

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    Establishment of ALSV-Induced Gene Silencing in Chinese Soybean Cultivars
    DONG YongXin,WEI QiWei,HONG Hao,HUANG Ying,ZHAO YanXiao,FENG MingFeng,DOU DaoLong,XU Yi,TAO XiaoRong
    Scientia Agricultura Sinica    2022, 55 (9): 1710-1722.   DOI: 10.3864/j.issn.0578-1752.2022.09.002
    Abstract310)   HTML51)    PDF (4153KB)(98)       Save

    【Objective】 The establishment of apple latent spherical virus (ALSV)-induced gene silencing on domestic soybean cultivars will offer a simple, time-saving and operable system for gene function and genetic breeding of soybean cultivars in China.【Method】The infectious clones of ALSV which was used to infect plant through Agro-infiltration was constructed. A 327 bp cDNA fragment of phytoene desaturase (GmPDS) cDNA was amplified from soybean cultivar Williams 82 and inserted into the pALSV2 vector. The pALSV1 and pALSV2-GmPDS were used to co-infect Nicotiana benthamiana plant through Agro-infiltration, and the ALSV virus particle was purified from systemic infected leaves of N. benthamiana plants at 17 days post infiltration (dpi). The purified virions were mechanically inoculated onto the first-round true leaves of soybean and photobleaching phenotype on the upper non-inoculated leaves was monitored from 10 to 30 dpi. Using the empty ALSV vector as a control, the gene expression levels of ALSV coat protein (CP) gene and GmPDS in ALSV:GmPDS infected soybean were examined by RT-PCR and quantitative RT-PCR analysis, respectively. 【Result】At 20 dpi, soybean cultivar Nannong 1138-2 inoculated with ALSV:GmPDS showed photobleaching phenotype in the systemic infected leaves, however Williams 82 did not show gene silencing phenotype of PDS in the systemic infected leaves. The results of qRT-PCR confirmed that the RNA expression level of GmPDS in Nannong 1138-2 was significantly reduced but ALSV:GmPDS was unable to silence PDS in Williams 82. By using the same method, the gene silencing efficiency of other 9 domestic soybean cultivars mediated by ALSV:GmPDS was examined. Soybean cultivars including Nannong 47, Andou 203, Xiangdou 4, Zhonghuang 13, Shanning 29 and Qihuang 34 all displayed photobleaching phenotype in plant systemic infected leaves after inoculation with ALSV:GmPDS, while GmPDS was not silenced in Hedou 12, Zhonghuang 311 and Shanning 16.【Conclusion】In this study, an Agrobacterium-mediated ALSV viral VIGS vector was constructed. ALSV virions was propagated and purified from N. benthamiana plant. The purified virions were rub inoculated onto the first-round true leaves of soybean. Finally, an efficient gene silencing system was established on a number of domestic soybean cultivars in China.

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    Function of FCS-Like Zinc-Finger Protein OsFLZ18 in Regulating Rice Flowering Time
    MA YaMei,ZHANG ShaoHong,ZHAO JunLiang,LIU Bin
    Scientia Agricultura Sinica    2022, 55 (20): 3875-3884.   DOI: 10.3864/j.issn.0578-1752.2022.20.001
    Abstract305)   HTML86)    PDF (1565KB)(161)       Save

    【Objective】Flowering time is an important agronomic trait which determines the yield and regional adaptability of rice, but the underlining molecular regulatory mechanism need further study. FCS-like Zinc finger proteins (FLZs) are a class of plant specific regulatory proteins which play essential roles in plant growth and stress response, but their functions in regulating flowering time have not been reported. This study aims to investigate the potential function of FLZ proteins in rice flowering time control. The finding will broaden our understanding on the molecular regulatory mechanism of rice flowering time.and provide new theoretical basis and gene resource for rice breeding. 【Method】Based on the target sequences published in RGAP database, OsFLZ18 overexpression vector and CRISPR-Cas9 vector were generated and introduced into Japonica variety Nipponbare by Agrobacterium tumefaciens-mediated genetic transformation assay. Homozygous CRISPR knockout mutants were screened by PCR and sequencing analyses. The quantitative real-time PCR (qRT-PCR) assay was used to examine the spatial-temporal expression and diurnal rhythmic expression of OsFLZ18, as well as the effects of OsFLZ18 on the transcription of several known flowering time-related genes. Yeast two-hybrid assay (Y2H) was used to test the interaction between OsFLZ18 and the flowering time-related regulatory proteins.【Result】OsFLZ18 was ubiquitously expressed in various rice tissues, with the highest expression level in 14 day-old seedling, followed by leaf sheaths and leaf blades at the tillering stage, and stem and young panicles at reproductive stages. The OsFLZ18-CRISPR vector was constructed and transformed into Nipponbare. Two independent homozygous OE lines (OE-2, OE-3) with higher OsFLZ18 expression level and two homozygous mutants (CRISPR-21, CRISPR-25) were selected for further study. Phenotypic observation showed that the OE lines flowered later than the wild-type plants under both natural long-day and short-day conditions in Guangzhou, while the CRISPR lines had no obvious differences in heading date when compared to the wild-type plants. The expression levels of Ehd1, Hd3a and RFT1 were significantly decreased in OE-2 plants compared with those in the wild-type plants under artificial short-day conditions, but no significant difference in the expression level of Hd1 was observed between them. The results of Y2H experiment showed that OsFLZ18 interacted with OsMADS51, a positive regulator of rice flowering time. Furthermore, OsFLZ18 exhibits a diurnal rhythmic expression profile, showing lower expression levels in the daytime and higher expression levels at night with a peak at midnight. 【Conclusion】Overexpression of OsFLZ18 delays rice flowering time.

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    Effects of Row Spacing and Plant Density on Grain Yield and Quality of Grain-Feeding Sorghum
    WANG JinSong,DONG ErWei,LIU QiuXia,WU AiLian,WANG Yuan,WANG LiGe,JIAO XiaoYan
    Scientia Agricultura Sinica    2022, 55 (16): 3123-3133.   DOI: 10.3864/j.issn.0578-1752.2022.16.005
    Abstract297)   HTML0)    PDF (517KB)(288)       Save

    【Objective】This study was conducted to clarify effects of different row spacings and planting densities on the development, yield, grain quality and NPK (nitrogen, phosphorus and potassium) accumulation of grain-feeding sorghum, and to identify the optimal cultivation mode in agro-pastoral ecozone of Shanxi, so as to provide the theoretical basis for the grain-feeding sorghum cultivation. 【Method】A new grain-feeding sorghum variety Liaoxialiang No. 1 was selected for this study. Field experiments were conducted during 2018 and 2019. Three row spacings were set, i.e. 30, 50, and 60 cm, respectively. And there were four planting densities (13.5×104, 16.5×104, 19.5×104 and 22.5×104 plants/hm2) at each row spacing. The plant height and biomass at heading stage, grain yield, NPK accumulation at harvest and grain quality in different row spacings and planting densities were analyzed. 【Result】There were significantly effects of row spacing, planting density and their interaction on the grain-feeding sorghum growth, nutrient accumulation, grain yield and quality. As plant density increased, the plant height, biomass and NPK accumulation at heading stage were increased. However, the biomass produced after heading, biomass and NPK accumulation at harvest, along with yield, increased first and then decreased with the increase of density under row spacing with 50 and 60 cm; Actually, the grain yield of feeding sorghum was positively correlated with biomass and N accumulation at harvest and the biomass produced after heading. The average grain yield, N and P accumulation and biomass after heading in row spacing of 50 cm were higher than those of 60 and 30 cm. Among the 12 treatments, the treatment with row spacing of 50 cm, planting density of 16.5×104 plants/hm2 had improved biomass and N accumulation at harvest, which were increased by 3.6%-12.8% and 3.6%-18.6%, respectively, relative to the average value of the total 12 treatments. The grain yield with row spacing of 50 cm and planting density of 16.5×104 plants/hm2 was the highest among all treatments, and they were 10 814 kg·hm-2 in 2018 and 12 434 kg·hm-2 in 2019, respectively. Starch and protein content of grain decreased with planting density increasing, but the influence of row spacing variation on them were less. Grain tannin content was significantly increased with planting density adding, while the row spacing increase also promoted tannin content. The influence of row spacing and planting density on tannin content was obvious, compared with those on starch and protein. Those treatments with row spacing of 50 cm and density of 16.5×104 plants/hm2 had similar tannin content with the average value of different treatments. 【Conclusion】Both N accumulation and biomass production after heading were important for high grain yield of feeding sorghum. The appropriate plant spacing under different row spacings could improve feeding sorghum grain yield, but affect grain quality, especially the tannin content. Row spacing of 50 cm and density of 16.5×104 plants/hm2 was recommended in agro-pastoral ecozone in Shanxi (with variety of Liaoxialiang No.1) in terms of grain yield and quality of feeding sorghum.

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    Application of Yr52 Gene in Wheat Improvement for Stripe Rust Resistance
    FANG TaoHong,ZHANG Min,MA ChunHua,ZHENG XiaoChen,TAN WenJing,TIAN Ran,YAN Qiong,ZHOU XinLi,LI Xin,YANG SuiZhuang,HUANG KeBing,WANG JianFeng,HAN DeJun,WANG XiaoJie,KANG ZhenSheng
    Scientia Agricultura Sinica    2022, 55 (11): 2077-2091.   DOI: 10.3864/j.issn.0578-1752.2022.11.001
    Abstract294)   HTML59)    PDF (1980KB)(117)       Save

    【Objective】 The objective of this study is to evaluate the application value of the high temperature adult plant (HTAP) resistance gene Yr52 in wheat production for improving stripe rust resistance. And wheat lines with good agronomic characters and high disease resistance were developed and selected. It laid a foundation for making full use of the existing HTAP resistance resources and improving the yield related traits.【Method】 The stripe rust resistance gene Yr52 was introgressed to Lunxuan 987 (LX987), Bainong Aikang 58 (AK58) and Han 6172 (H6172) by backcrossing and self-crossing combined with marker-assisted selection breeding. Adult-plant resistance of donor parent, receptor cultivars and their progeny lines were evaluated in the disease nursery fields at Mianyang, Sichuan and Yangling, Shaanxi by mixed endemic physiological races CYR32, CYR33 and CYR34. In comparison to the Chinese Spring reference genome, the flanking SSR markers Xcfa2040 (6.8 cm-Yr52) and Xbarc182 (1.2 cm-Yr52) of Yr52 were combined to search for markers of 35K SNP chip in the physical interval of target genes, and developed into derived cleaved amplified polymorphic sequences (dCAPS) and kompetitive allele specific PCR (KASP) markers. The resistance gene Yr52 was detected in BC2F5:6 progeny lines.【Result】 The evaluation of adult plant resistance and agronomic traits indicated that nineteen BC2F5:6 lines with LX987 background was obtained: Among of them, 11 were high resistance (IT=0-3, DS=1%-20%), 8 were moderate resistance (IT=4-6, DS=15%-30%), the average thousand kernel weight (TKW), kernels per spike (KPS), productive tiller number per line (PTN), plant height (PH) and spike length (SL) was 45.33 g, 46, 7, 113.26 cm and 10.05 cm, respectively. Four BC2F5:6 families with AK58 background: all showed high resistance (IT=0-3, DS=5%-25%); the average TKW, KPS, PTN, PH and SL were 44.67 g, 48, 7, 96.54 cm and 10.17 cm, respectively. Five BC2F5:6 lineages with H6172 background showed high resistance to stripe rust (IT=0-3, DS=5%-20%). The average TKW, KPS, PTN, PH and SL were 43.74 g, 49, 8, 109.72 cm and 10.06 cm, respectively. The detection rate of three simple sequence repeat (SSR) molecular markers Xbarc182, Xcfa2040 and Xwmc557 linked to Yr52, in offspring population were 78.57%, 66.67% and 66.67%, respectively. One dCAPS marker Xdcaps-Yr52-1 and one KASP marker Xkasp-Yr52-1 were successfully developed, and the detection rates were 73.68% and 41.67%, respectively. The agronomic traits of lines with high (IT=0-3) and medium (IT=4-6) resistance levels were compared. The results showed that the average TKW (P>0.05), PTN (P>0.05) and KPS (P<0.05) of lines with IT=0-3 were higher than those of families with moderate resistance level lines (IT=4-6). Five lines with disease resistance and stable agronomic traits were selected by evaluated of PH=80-105 cm, PTN≥6,KPS≥45, TKW≥42 g, SL≥8 cm.【Conclusion】 Yr52 was found to be resistant to all of the present predominant races in the adult plant stage. After introgression Yr52 into the main susceptible Chinese wheat varieties, the progeny lines with good disease resistance and agronomic characters could be used for breeding resistance varieties with multi-gene polymerization, it is enriching for the diversity of disease resistance genes and achieving durable utilization. The development of molecular markers will facilitate detect the utilization of Yr52 gene in resistance identification of germplasm in the future.

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    Effects of Water-Saving Irrigation on Grain Yield and Quality: A Meta-Analysis
    MENG Yi,WENG WenAn,CHEN Le,HU Qun,XING ZhiPeng,WEI HaiYan,GAO Hui,HUANG Shan,LIAO Ping,ZHANG HongCheng
    Scientia Agricultura Sinica    2022, 55 (11): 2121-2134.   DOI: 10.3864/j.issn.0578-1752.2022.11.004
    Abstract293)   HTML43)    PDF (1454KB)(177)       Save

    【Objective】 Compared with continuous flooding, the water-saving irrigation can increase water use efficiency. However, the effects of water-saving irrigation on yield and quality in rice paddies have not been clearly defined. The objective of this study was to identify the systematic effects of water-saving irrigation on rice yield and quality through Meta-analysis techniques. 【Method】 In the present study, a total of 34 studies that adapted a water-saving treatment and continuous flooding as the control involving 263 paired observations were included across this dataset. The meta-analysis was conducted to identify the responses of yield and quality to water-saving irrigation as affected by experimental type, water-saving irrigation type, cropping system, rice type, the period of water-saving irrigation, soil total nitrogen (N), soil texture, N rate, and the number of N application. 【Result】 Overall, the water-saving irrigation did not significantly affect grain yield and quality relative to continuous flooding. In terms of water-saving irrigation type, the moderate water-saving irrigation increased brown rice rate (+0.9%), milled rice rate (+1.5%), and head milled rice rate (+2.3%), but did not affect grain yield, chalkiness percentage, chalkiness degree, length/width ratio, amylose content, gel consistency, and protein content relative to continuous flooding. However, the severe water-saving irrigation significantly decreased grain yield (-22.1%), brown rice rate (-2.7%), milled rice rate (-2.7%), and head milled rice rate (-3.6%), and increased chalkiness percentage (+28.0%) and chalkiness degree (+46.7%), while no marked differences were observed on length/width ratio, amylose content, gel consistency, and protein content. Furthermore, compared with continuous flooding, the water-saving irrigation reduced protein content (-9.8%) of late rice, but did not affect that of early rice, middle rice, and single rice. 【Conclusion】 Compared with continuous flooding, the moderate water-saving irrigation could improve rice milling quality, and did not affect grain yield, appearance quality, cooking and eating quality, and nutrition quality. The severe water-saving irrigation significantly reduced rice yield, milling quality, and appearance quality, while no significant effects were found on cooking and eating quality and nutrition quality. The results provided an insight to evaluate the responses of grain yield and quality to water-saving irrigation.

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    Characteristics and Cold Tolerance of Upland Cotton Genetic Standard Line TM-1
    WANG JunJuan,LU XuKe,WANG YanQin,WANG Shuai,YIN ZuJun,FU XiaoQiong,WANG DeLong,CHEN XiuGui,GUO LiXue,CHEN Chao,ZHAO LanJie,HAN YingChun,SUN LiangQing,HAN MingGe,ZHANG YueXin,FAN YaPeng,YE WuWei
    Scientia Agricultura Sinica    2022, 55 (8): 1503-1517.   DOI: 10.3864/j.issn.0578-1752.2022.08.003
    Abstract283)   HTML37)    PDF (6422KB)(85)       Save

    【Objective】We systematically investigated the major agronomic traits and cold tolerance of accession TM-1 at the bud and seedling stages. The relative expressions of cold tolerance-related genes were analyzed by the qRT-PCR method. The cold tolerance mechanism of TM-1 was further discussed, which provides the theoretical basis for the breeding utilization of TM-1.【Method】The major agronomic traits of TM-1 were manually investigated in the field using variety CRI35 as the control. The fiber quality was assessed by an international calibrated cotton standard (HVICC), and the insect resistance (Bt) was detected by kanamycin screening and molecular detection technologies. For the cold tolerance testing, two contrasting accessions, cold-resistant accession Yu 2067 and cold-sensitive variety Hengmian 3 were set as controls, respectively. The cold resistance of TM-1 at bud stage and cotyledon stage was identified, treated at 4℃ and then recovered under normal conditions for 7 days, and the relative cotyledon spreading rate and the cold injury levels of plants were investigated, and cold injury indexes and cold resistance indexes were calculated. The portable chlorophyll meter was used for in vivo testing the leaf relative chlorophyll content (represented by SPAD value). The expressions of cold tolerance-related genes in leaves were measured by qRT-PCR method. 【Result】 The leaves of TM-1 were large and dark green. The pre-frost seed cotton yield was 2 791.50 kg·hm-2, and the plant height was 94.60 cm. The growth period was about 135 days, and the yield, plant height, fruit branch number per plant, boll number per plant were higher than CRI35, while other agronomic traits were similar to CRI35. TM-1 had medium fiber quality. The test results of kanamycin and test paper showed that TM-1 did not contain the Bt like CRI35. Identification results of cold tolerance at bud stage showed that compared with the control treatment, the relative chlorophyll content and plant height of TM-1 decreased significantly. Low-temperature stress significantly inhibited hypocotyl elongation and chlorophyll synthesis in cotton leaves. Under low-temperature treatment, the taproots of TM-1 were damaged, but the lateral roots were more developed than those of the control. The cold tolerance level of TM-1 reached high cold resistance at the bud stage. Identification of cold tolerance at the cotyledon stage showed that the relative chlorophyll content and plant height of TM-1 decreased significantly compared with the control. The cold tolerance index of TM-1 at the cotyledon stage was 85.32%, which was significantly higher than Yu 2067, and the tolerance level of TM-1 reached cold resistance at the cotyledon stage. After the treatment of low-temperature stress for 24 h at the trefoil stage, nine genes were up-regulated in the TM-1 leaves, and their up-regulated expression folds were significantly higher than those of cold-sensitive accession. Dehydrin gene was up-regulated in TM-1 leaves, and the expression fold was similar to that in the leaves of Yu 2067, which was 4.69 times that in the leaves of Hengmian 3. The expression fold of the LEA3 gene in TM-1 leaves was significantly higher than that of Yu 2067 and Hengmian 3. 【Conclusion】 Accession TM-1 has stable agronomic characters and the medium fiber quality. It can be used as an ideal receptor for transferring exotic genes because without Bt. TM-1 can also be used as an important parent for cotton breeding and a gene source for cloning genes because of its good cold tolerance.

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    Geostatistical Characteristics of Soil Data from National Soil Survey Works in China
    ZHANG WeiLi,FU BoJie,XU AiGuo,YANG Peng,CHEN Tao,ZHANG RenLian,SHI Zhou,WU WenBin,LI JianBing,JI HongJie,LIU Feng,LEI QiuLiang,LI ZhaoJun,FENG Yao,LI YanLi,XU YongBing,PEI Wei
    Scientia Agricultura Sinica    2022, 55 (13): 2572-2583.   DOI: 10.3864/j.issn.0578-1752.2022.13.008
    Abstract275)   HTML41)    PDF (2252KB)(138)       Save

    【Objective】China carried out the second state soil survey from 1979 to 1987 and the soil nutrient investigation of farmland from 2005 to 2017. Both surveys covered the whole country with a huge amount of ground soil samplings. The data generated from the two surveys have become the most detailed spatial-temporal data for soil types and quality in China. The purpose of the study was to test and to evaluate the geostatistical characteristics of the data by geostatistical testing approach, so as to provide the reference for the use of these data to characterize the temporal and spatial distribution of soil features in different disciplines. 【Method】7 testing areas were selected to represent different regions in China. Soil organic matter (SOM) contents of 0-20 cm soil layer from soil profile sampled in 1979-1987 and from plough layer sampled in 2005-2017 were extracted from the corresponding data bases. The ground sampling for soil profiles in 1979-1987 was to give priority to typical soil types firstly and secondly to keep an evenly distributed sampling as possible. 100 000 soil profiles with about 1m soil deep were finally sampled. After integrated data processing and coordinate matching, 60 000 profiles obtained coordinates. Ground sampling for soil plough layer in 2005-2017 was in grid distribution. 10 000 000 plough layer soil samples with GPS positioning coordinates have been completed. For each testing area, the data set contained two groups, about 500-1 300 SOM values from soil profile data and 50 000-250 000 values from plough layer data. The data from two time groups of each testing data set were analyzed by ordinary Kriging approach separately. 80% of the data were randomly selected as the training sample set for modeling and 20% as the verification sample set. The linear regression between the predicted value and the measured value of the validation sample was carried out. R2 (coefficient of determination) and RMSE (root mean square error) were calculated to evaluate the reliability and uncertainty of the data sets in expressing the spatial distribution of the soil feature. 【Result】It was showed that the reliability of mapping SOM content by profile data of all of the 7 testing areas reached significant levels. However, the deviation between predicted values and measured values of the test data set was relatively great. The values of R2 were low, between 0.223-0.380 and RMSE were relatively high. Testing results by soil plough layer data sampled in 2005-2017 showed that through large sample size and grid sampling, the reliability and prediction accuracy of mapping SOM content were improved greatly, for R2 increased and RMSE decreased. The geostatistical test results of two periods with a time interval of 30 years showed that although there were some changes in the contents of soil organic matter, the overall spatial distribution of SOM content in each testing area expressed by the two data groups was similar. 【Conclusion】 The reliability and accuracy of soil maps were much better in terms of characterizing the spatial distribution of soil features, when the soil investigation was by means of a large sample size with grid sampling. It meant that the reliability and accuracy of the original large-scale soil thematic maps, such as maps of soil types, organic matter, pH value, soil nitrogen, phosphorus and potassium nutrient contents from second state soil survey, were better than maps generated by profile data, as these original large-scale soil thematic maps were derived from the large sample size with grid sampling. However, the data of 60 000 soil profiles from second state soil survey, which contained many soil features and could supply reliable soil thematic maps, were also of great importance for understanding spatial characteristics of these soil features. It has been showed that a large sample size was essential for a precise and accurate mapping of soil feature of the whole country. For mapping long-term changing or stable soil features such as soil types, texture and morphological features, it would be difficult to obtain reliable maps by a soil sample size much less than the second state soil survey. Considering the current requirements and the available data resources in China, the soil investigation in the future could be mainly focused in investigating data missing areas as well as some missing soil features for soil functions.

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    Effect of Drip Fertigation Mode on Maize Yield, Nutrient Uptake and Economic Benefit
    LI Qian,QIN YuBo,YIN CaiXia,KONG LiLi,WANG Meng,HOU YunPeng,SUN Bo,ZHAO YinKai,XU Chen,LIU ZhiQuan
    Scientia Agricultura Sinica    2022, 55 (8): 1604-1616.   DOI: 10.3864/j.issn.0578-1752.2022.08.011
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    【Objective】 To study the effects of different drip fertigation modes on maize yield, nutrient absorption, soil nitrogen balance, water use efficiency and economic benefits, in order to provide a theoretical basis for drip irrigation maize production in semi-arid area of Jilin province.【Method】Field experiment was carried out in Minle Village of Jilin Province for 2018-2019. Five treatments were set up: drip fertigation with plastic film (DFM), shallow buried drip fertigation (DF), shallow buried drip fertigation urea (DIU), shallow buried drip irrigation (DI), and farmer practices (FP). We collected plant samples at jointing stage, bell stage, silking stage, filling stage and mature stage, divided into stem, leaf and grain parts, measured the shoot dry matter weight and the contents of nitrogen, phosphorus and potassium, respectively. Based on these data, the nutrient absorption were calculated or evaluated. The soil samples from 0-100 cm soil depth were respectively collected before sowing and after harvest of maize to study soil nitrogen balance.The soil samples from 0-200 cm soil depth were respectively collected before sowing and after harvest of maize to study water use efficiency.【Result】The maize yield of drip fertigation treatments (DFM, DF, DIU and DI) were higher than farmers' conventional treatment 10.3%-20.6%, the rate of yield increase in the dry year (2018) (13.7%-27.9%) was higher than that in the rainy year (2019) (7.2%-13.7%), meanwhile, the accumulation of nitrogen, phosphorus and potassium in mature stage was increased by 15.7%-31.7%(P<0.05), 11.0%-35.6% (P<0.05) and 5.2%-20.9%, especially increased the nitrogen, phosphorus and potassium uptake after silking by 63.1%-95.2% (P<0.05), 11.6%-63.0% and 40.0%-110.0% (P<0.05); it also significantly increased the water use efficiency (WUE) by 21.8%-33.9% and decreased the apparent nitrogen loss by 13.8%-92.0%. Compared with shallow buried drip fertigation (DF), DFM treatment increased the yield and water use efficiency in dry years, but differences were not significant in rainy years, DFM treatment significantly reduced soil nitrogen apparent loss by 74.2%, but there was no significant difference in net income between in two treatments, and the benefit/cost ratio of DFM treatment was lower than that of DF treatment significantly. Under shallow buried drip irrigation, there were no significant differences in maize yield, nitrogen apparent loss and water use efficiency between DF and DIU treatments. However, the accumulation of dry matter and P and K in DF treatment at mature stage were significantly higher than those in DIU treatment. There was no significant difference between DF treatment and DIU treatment in net income and benefit/cost ratio. The maize yield of DI treatment was 13.7% higher than that of FP treatment in dry years, but not significantly in rainy years. It also significantly increased N and P accumulation at mature stage and N and K accumulation after silking. The net income of DI treatment was not significantly different from that of FP treatment, but the ratio of production and input was significantly lower than that of FP treatment.【Conclusion】Drip fertigation mode could increase maize yield, N, P and K accumulation and water use efficiency, and reduce N apparent loss in semi-arid areas, and the effect was significant in dry years. The advantage of DFM treatment were greater than DF, but the benefit/cost ratio was lower than DF. There was no significant difference in the yield, nutrient uptake and water use efficiency, net income and the benefit/cost ratio between shallow buried drip fertigation urea technology and shallow buried drip fertigation technology, the low cost DIU treatment simplified the production process, and also had the obvious effect on increasing grain yield. In conclusion, shallow buried drip fertigation urea mode was suitable for the current situation of maize production in semi-arid area of Jilin Province.

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    Mechanism of NMRAL1 Regulating Influenza Virus Replication
    YAN Ya,WANG GuangWen,KONG FanDi,WANG XuYuan,WANG YiHan,LI JunPing,ZHAO YuHui,LI ChengJun,CHEN HuaLan,JIANG Li
    Scientia Agricultura Sinica    2022, 55 (10): 2067-2076.   DOI: 10.3864/j.issn.0578-1752.2022.10.016
    Abstract268)   HTML24)    PDF (2881KB)(56)       Save

    【Objective】Influenza virus is a zoonotic pathogen that often causes a pandemic and poses a great threat to human health, and the influenza viruses are prone to variants and can constantly escape the host cell immune response and develop resistance to existing anti-influenza drugs, so the search for new ways to fight influenza is imminent. This study aimed to explore the effect of NMRAL1 (NmrA-like family domain-containing protein 1) on influenza virus replication, and to reveal the molecular mechanism by which it functioned, so as to provide a potential target for anti-influenza drugs development. 【Method】In this study, siRNA interference technology was used to down regulate the expression of NMRAL1 in A549 cells, and the expression levels of NMRAL1 were detected by Western Blot. Virus titers in cell supernatants at 24 h and 48 h after infection with two different subtypes influenza viruses, including a/Anhui/ 2/2005(AH05)(H5N1) and a/WSN/33(H1N1), were detected using the plaque assay. To determine the specific stage at which NMRAL1 affected influenza virus replication, NMRAL1 was overexpressed by transiently transfecting NMRAL1-Myc-pCAGGS plasmid in HEK293T cells, and the effect of overexpressing NMRAL1 on influenza virus polymerase activity was examined by luciferase reporter system. The influenza virus NP protein was stained by using immunofluorescence, and the down-regulated expression of NMRAL1 on the localization of NP protein at 3, 4, 5, 6 and 8 h post infection was assessed respectively by confocal assay to determine whether down-regulated expression of NMRAL1 affected the process of influenza virus vRNP import and export. Western Blot was used to detect the effect of NMRAL1 knockdown on the expression of viral proteins and on the expression of IFN stimulated genes (ISGs) downstream of type I interferon pathway activated by influenza virus. Indirect immunofluorescence assay was utilized to further verify the effect of NMRAL1 on influenza virus replication. 【Result】Western Blot assay showed that NMRAL1 siRNA could significantly down regulate NMRAL1 expression in A549 cells. With the down-regulated expression of NMRAL1, A549 cells were infected with H5N1 and H1N1 viruses, respectively. Then the virus titers in the cell supernatant were measured by plaque assay, which showed that the virus titers in the supernatant of cells at 24 and 48 h after infection with H5N1 or H1N1 were significantly decreased, meaning that NMRAL1 could promote the replication of different subtypes influenza viruses. To further explore the specific mechanism by which NMRAL1 regulated influenza virus replication, a luciferase reporter system was used to detect influenza virus polymerase activity, and it was found that the overexpression of NMRAL1 had no effect on influenza virus polymerase activity. The results of confocal assay showed that the down-regulated expression of NMRAL1 did not affect the process of NP nuclear import and export, meanwhile Western Blot assay indicated that down-regulated expression of NMRAL1 did not affect the expression of each viral protein. However, the results of the fluorescence quantitative PCR assay showed that down-regulated expression of NMRAL1 was able to promote the up-regulation of IFN-β mRNA levels induced by influenza virus infection, and Western Blot assay found that down expression of NMRAL1 promoted the expression of MxA and IFITM3 antiviral proteins downstream of type I interferon pathway. Meanwhile, the indirect immunofluorescence assay showed that the down expression of NMRAL1 could significantly inhibit influenza virus replication. 【Conclusion】 Those results demonstrated that, during influenza virus infection, NMRAL1 did not affect the process of influenza virus invasion as well as transcription translation, but rather inhibited the expression of antiviral factors, such as MxA and IFITM3, by inhibiting type I interferon pathway activation, which ultimately promoted influenza virus replication. This study confirmed that the host factor NMRAL1 positively regulated influenza virus replication and enriched the network of host factors involved in influenza virus replication.

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    Optimization of Callus Genetic Transformation System and Its Application in FtCHS1 Overexpression in Tartary Buckwheat
    ZHAO HaiXia,XIAO Xin,DONG QiXin,WU HuaLa,LI ChengLei,WU Qi
    Scientia Agricultura Sinica    2022, 55 (9): 1723-1734.   DOI: 10.3864/j.issn.0578-1752.2022.09.003
    Abstract266)   HTML35)    PDF (2457KB)(139)       Save

    Objective】To develop a novel tool for functional verification and molecular breeding in tartary buckwheat, this study focused on establishing and optimizing an efficient callus genetic transformation system. 【Method】Callus induction factors including different explants, ratios of diverse growth regulators, and Agrobacterium tumefaciens types were systematically evaluated using “Xiqiao No. 2” as the derived plant. We further overexpressed FtCHS1, a key enzyme gene involved in the biosynthesis of tartary buckwheat flavonoids in obtained calli to validate the optimized genetic callus transformation system. The positive transgenic lines were confirmed by PCR and fluorescent observation. Subsequently, the content of anthocyanins and metabolites in flavonol branch pathway were determined by UV spectrophotometry and High Performance Liquid Chromatography (HPLC), respectively. Furthermore, quantitative real-time PCR was performed to analyze expression levels of genes involved in flavonoid synthesis, in order to compare the differences between the FtCHS1-overexpressed calli and the control. 【Result】The optimal explant was hypocotyls and the optimal induction medium was the Murashige and Skoog (MS) medium supplemented with the addition of 0.8 mg·L-1 6-BA (6-Benzylaminopurine) and 3.5 mg·L-1 2,4-D (2,4-Dichlorophenoxyacetic acid). The induction rate of calli grown on the above medium reached up to 72%. Moreover, the optimized subculture medium containing MS with the additives of 3 mg·L-1 6-BA and 1 mg·L-1 KT (Kinetin) increased the percentage and coefficient of callus proliferation to 98% and 1.09, respectively. Additionally, the best Agrobacterium tumefaciens in the transformation process was GV3101, and the transformation efficiency was up to 31.3%. The functional analysis of FtCHS1 overexpressing in transgenetic calli demonstrated that: (1) The accumulations of kaempferol and quercetin in transgenic calli overexpressing FtCHS1 were dramatically higher than those in control groups (P<0.01), and anthocyanin, rutin and myricetin contents were also remarkably higher (P<0.05); (2) Overexpression of the exogenous FtCHS1 did not affect the expression levels of 5 endogenous orthologous genes FtCHSs in the transgenic calli (P>0.05), whereas genes encoding key enzymes of the flavonoid synthesis pathway, such as FtCHI, FtF3H, FtFLS1, FtFLS2, FtFLS3, and FtDFR1, were up-regulated (P<0.05); (3) FtMYB5 and FtMYB6, the transcription factor genes that specifically positively regulated the flavonol synthesis, were up-regulated, while FtMYB8, a suppressor gene of anthocyanin synthesis, was down-regulated (P<0.05). 【Conclusion】In this study, the callus genetic transformation system of tartary buckwheat was successfully established from “Xiqiao No. 2”. FtCHS1 overexpression in the transgenic calli up-regulated genes related to flavonoid synthesis, resulting in flavonoids accumulation.

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    Comprehensive Evaluation of Potato Tuber Texture
    LI WenLi, YUAN JianLong, DUAN HuiMin, JIANG TongHui, LIU LingLing, ZHANG Feng
    Scientia Agricultura Sinica    2022, 55 (12): 2278-2293.   DOI: 10.3864/j.issn.0578-1752.2022.12.002
    Abstract264)   HTML56)    PDF (3410KB)(122)       Save

    【Objective】 The comprehensive evaluation of texture qualities of potato tubers not only are beneficial to the subdivision of processing quality traits and accurately locate purpose of potato, but also assist breeders screening new varieties, and accelerate the development of potato products.【Method】Potato cultivated varieties were selected as the research samples. Puncture, TPA compression and shear methods were chosen to analyze the texture parameters. These included puncture distance, puncture initial force, puncture speed, compression deformation, compression speed, compression interval time, compression initial force, shear initial force and speed. The texture indexes of eight varieties were measured under the optimal texture analyzer parameters setting, then the correlation among the texture parameters and the evaluation of optimal texture parameters were analyzed. 【Result】 Optimal parameters of fresh tuber puncture: Cylindrical metal probe (TMS 2 mm Steel), 2 mm puncture distance and, 2.5 N initial force, 50 mm·min-1 detection speed. The optimal test factors of TPA compression (fresh/steamed): The cylinder sample for fresh and steamed tubers both ranged in the diameter and height from 10 mm to 15 mm, no significant difference was examined among three probe selection in the fresh tubers. Cylindrical aluminum probe (TMS 36.0 mm Aluminum Cylinder) was the optimal type for steamed tubers probe. The optimal parameters (fresh/steamed): 50% and 60% deformation, 60 mm·min-1 and 80 mm·min-1 detection speed, 6 s and 10 s interval time, both 0.7 N initial force. The optimal shear parameters (fresh/steamed): The length, width and height of the cuboid sample were 30 mm, 15 mm, and 10 mm, respectively. The probe type was light single knife probe (TMS Perspex Knife Edge), with both 60 mm·min-1 detection speed, and 1 N and 0.5 N initial force. They’re existed significant correlation between springiness and the peel crispness, no significant correlation among the other texture parameters of TPA compression and shear. They’re existed significant positive correlation among puncture, TPA compression and shear texture parameters (0.410-0.959) in fresh tubers. There also existed significant positive correlation between TPA compression and shear texture parameters (0.441-0.952) in steamed tubers. 【Conclusion】 Puncture, TPA compression and shear methods were suitable for the samples evaluation of the quality of fresh tubers. The indexes of peel hardness, peel brittleness, TPA hardness, cohesiveness, chewiness, shear hardness can be chosen as important parameters to compare differences of texture. TPA compression and shear methods were suitable for the sample’s evaluation of the quality of steamed tubers. The indexes of TPA hardness, adhesiveness, cohesiveness, springiness, chewiness, shear hardness can be chosen as important parameters to compare differences of texture.

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    Understanding and Thinking About Some Problems of Fruit Tree Germplasm Resources and Genetic Breeding
    CHEN XueSen,WANG Nan,ZHANG ZongYing,MAO ZhiQuan,YIN ChengMiao
    Scientia Agricultura Sinica    2022, 55 (17): 3395-3410.   DOI: 10.3864/j.issn.0578-1752.2022.17.011
    Abstract263)   HTML33)    PDF (743KB)(139)       Save

    This review summarized the research progress of fruit tree germplasm resources and genetic breeding as well as the understanding and thinking of several issues. The main results were as follows: 1. Although China was the world’s largest fruit tree resource country and the origin and evolution center (one of) of many fruit trees, such as citrus, apple, pear, peach, longan, loquat, banana, kiwi, plum, apricot, jujube and persimmon, the discovery, innovation and utilization of wild germplasm and famous local varieties needed to be further strengthened. 2. According to the source of genetic variation, the fruit tree breeding mainly had two approaches: hybrid breeding and bud sports selection; the first generation of fruit tree hybrids was widely separated, and the genotype with the strongest heterosis was selected for each breeding. It became a new variety through asexual reproduction, and was used for a long time in production. The three hypotheses of dominant, superdominant and epistasis were the main genetic basis of heterosis; the analysis of the main characters of the new varieties of Fuji and Luli apples, Muscat Hamburg grape, and Shannongsu pear and their parents showed that selecting varieties with complementary traits as hybrid parents and selecting varieties with complex genetic background as female parents were important guidelines for the efficient utilization of fruit tree heterosis. Hybrid breeding was to determine the breeding goals according to the variety needs of the industry, to carry out parental selection and matching, and to breed new varieties with complementary parental traits and obvious heterosis. Bud mutation selection was the use of somatic natural mutations and epigenetics to repair and improve the individual traits of the main plant varieties in production; therefore, the organic combination of hybrid breeding and bud sports selection was an important technical approach to solve the variety problem of fruit tree industry. 3. In the face of rural revitalization and the country’s reform of the talent evaluation mechanism of “Persist in evaluating talents based on ability, actual performance and contribution, and overcome the tendency of only education, qualifications, and papers”, this review explained the scientific research ideas and classic cases that agricultural scientists must adhere to “Equal emphasis on technological innovation and the combination of good varieties and methods”.

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    Yield of Wheat and Maize and Utilization Efficiency of Nitrogen, Phosphorus and Potassium in Xinjiang
    TANG MingYao,SHEN ChongYang,CHEN ShuHuang,TANG GuangMu,LI QingJun,YAN CuiXia,GENG QingLong,FU GuoHai
    Scientia Agricultura Sinica    2022, 55 (14): 2762-2774.   DOI: 10.3864/j.issn.0578-1752.2022.14.007
    Abstract260)   HTML36)    PDF (1189KB)(124)       Save

    【Objective】The objectives of the present paper were to understand current status of fertilizer utilization efficiency of wheat and maize in Xinjiang, to optimize their nutrient management, and to improve fertilizer utilization efficiency, so as to provide basic data and technique support for the food security of Xinjiang and as well as all the country. 【Method】72 field trials (40 for wheat and 32 for maize) were carried out in main grain growing areas of Xinjiang from 2018 to 2020. Four different treatments of fertilizer application were designed, including nitrogen, phosphorus and potassium (NPK), no nitrogen (PK), no phosphorus (NK), and no potassium (NP). Each experiment was conducted in triplicate. Then, the nutrient uptake of main grain crops, the response of nitrogen, phosphorus, and potassium fertilizers, the agronomic efficiency, the utilization rate and other parameters were examined under the current conditions of fertilization for agricultural production in Xinjiang. 【Result】(1) The average application amounts of N, P and K fertilizers for wheat in Xinjiang were 233.1 kg N·hm-2, 128.0 kg P2O5·hm-2 and 75.5 kg K2O·hm-2, respectively; the average application amounts of N, P and K fertilizers for maize were 254.9 kg N·hm-2, 148.0 kg P2O5·hm-2 and 67.8 kg K2O·hm-2, respectively. (2) The wheat yield of per unit area was 7 505 kg·hm-2 under NPK treatment, and the yield responses of N, P and K fertilizers were 2 206 kg·hm-2 (500-3 795 kg·hm-2), 2016 kg·hm-2 (288-4 230 kg·hm-2), and 1 362 kg·hm-2 (105-2 910 kg·hm-2), respectively. The average rates of yield increase for N, P and K fertilizers were 45.0%, 39.7% and 23.0%, respectively. The yield per unit area of maize under NPK treatment was 13 715 kg·hm-2, and the yield responses of N, P and K fertilizers were 4 657 kg·hm-2 (1 559-6 900 kg·hm-2), 1 942 kg·hm-2 (473-4 699 kg·hm-2), and 1 297 kg·hm-2 (113-5 440 kg·hm-2), respectively. The average rates of yield increase for N, P and K fertilizers were 52.2%, 21.2%, and 15.5%, respectively. (3) The uptakes of N and K by wheat and maize were relatively large, whereas the uptake of phosphorus was relatively small. The application of chemical fertilizers could significantly promote the uptake of nitrogen, phosphorus and potassium by plants, and increase the accumulation of nitrogen, phosphorus and potassium in soil. For NPK treatment, it required 2.7 kg (1.7-4.0 kg) of nitrogen (N), 0.8 kg (0.4-1.3 kg) of phosphorus (P2O5), and 2.1 kg (1.2-3.9 kg) of potassium (K2O) to form 100 kg of grains for wheat; for maize using the NPK treatment, it required 2.1 kg (1.5-2.9 kg) of nitrogen (N), 0.8 kg (0.4-1.2 kg) phosphorus (P2O5), and 2.1 kg (0.7-3.4 kg) of potassium (K2O) to form 100 kg of grains. (4) The agronomic efficiency of nitrogen fertilizer for maize was higher than that of wheat. There were no significant differences in the agronomic efficiencies of phosphorus and potassium fertilizers. The agronomic efficiencies of N, P and K fertilizers for wheat were 9.6, 15.9 and 18.7 kg·kg-1, respectively. Therefore, the agronomic efficiencies of P and K fertilizers were significantly higher than that of nitrogen fertilizer. The agronomic efficiencies of nitrogen, phosphorus, and potassium fertilizers for maize were 18.7, 13.4 and 18.1 kg·kg-1, respectively, N and K fertilizers were significantly higher than P fertilizer. (5) The utilization rates of N, P and K fertilizers for wheat were 41.4%, 21.8% and 45.2%, respectively. The utilization rates of N, P and K fertilizers for maize were 46.9%, 20.5% and 49.6%, respectively. The N and K utilization efficiency for wheat and maize were significantly higher than that of P. 【Conclusion】To date, the yield of wheat and maize in Xinjiang was high, the utilization efficiency of nitrogen, phosphorus and potassium was at a high level, and the utilization efficiency of nitrogen and potassium was significantly higher than that of phosphorus. In Xinjiang, wheat and maize yield was most sensitive to nitrogen deficiency. The phosphorus deficiency had lower influence on the wheat and maize yield, and the potassium deficiency had the lowest reduction. The amount of nitrogen application applied to wheat and maize in Xinjiang was reasonable. In contrast, the amount of potassium application was seriously insufficient. The excessive application of phosphate in wheat existed. In the future, it was necessary to increase the input of potassium fertilizer for wheat and maize and to reduce the input of phosphorus fertilizer for wheat.

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    Evolutionary Relationship Between Transposable Elements and Tandem Repeats in Bovinae Species
    ZHANG Rui,ZHANG TianLiu,FAN TingTing,ZHU Bo,ZHANG LuPei,XU LingYang,GAO HuiJiang,LI JunYa,CHEN Yan,GAO Xue
    Scientia Agricultura Sinica    2022, 55 (9): 1859-1867.   DOI: 10.3864/j.issn.0578-1752.2022.09.014
    Abstract259)   HTML23)    PDF (1506KB)(47)       Save

    【Objective】The repetitive sequence is an important part of eukaryotic genomes and plays an important role in species evolution, gene genetic variation, and transcriptional regulation. The purpose of this study was to reveal the characteristics of tandem repeats in bovinae by investigating the evolutionary relationship between transposons and tandem repeats, so as to provide the theoretical support for the study of tandem repeats in bovinae. 【Method】 In this paper, the six genomes were selected as research object, including Bos taurus, Bos indicus, Bos mutus, Bubalus bubalis, Bison bison and Bos frontalis. The transposable elements and tandem repeats in six genomes was identified through TRF and RepeatMasker software. Meanwhile, the sequence similarity between the two types of tandem repeats was analyzed by BLAST, and single-locus tandem repeats (single-locus TRs, mlTRs), multiple-locus tandem repeats (multiple-locus TRs, mlTRs) and the characteristics of tandem repeat for the transposable elements were investigated too. 【Result】 (1) In the six bovinae genomes, the percent of tandem repeats in Bos taurus was the highest (49.13%), followed by Bos frontalis (46.82%), Bubalus bubalis (46.23%), Bos indicus (42.70%), Bos mutus (42.53%), and Bison bison (42.36%), in which the content of transposable elements in the genome ranged from 40.57%-45.71%, and was higher than that of tandem repeats (1.50%-3.42%). (2) In the tandem repeats, the proportion of mlTRs (76%-99%) was significantly higher than that of slTRs(1%-24%), indicating that the mlTRs was the main component of tandem repeats in six bovinae species. (3) The proportion of TE-derived tandem repeats was 43% to 84%, among them mutiple-locus tandem repeats could reach up to 94%. (4) The analysis of TRs-related transposable elements and their activity showed that these transposable elements were mainly from non-Long Terminal Repeats (non-LTR, including SINE and LINE) and long interspersed nuclear element (LINE), among which SINE/core-RTE (mainly BOV-A2) had the highest number (14 423-24 193) and relative number (4.06%-6.77%), which was considered to be the youngest and the most dynamic transposable elements. (5) The study on transposable elements of tandem repeats’ characteristics indicated that BovB and L1_BT contained a large number of tandem repeats in 0-600 bp and 1 500 bp-2 700 bp, respectively, which were more than 93% and 87% consistent with the consensus sequence, respectively, and the sequences were located in the non-coding region. 【Conclusion】 The repetitive sequence had similar distribution characteristics, non-LTR was an important source of TRs-related TEs, and SINE/Core-RTE(mainly BOV-A2) was the youngest and most dynamic transposable elements. At the same time, the tandem repeats could be used as internal structure component of transposable elements, indicating that tandem repeats and transposable elements interacted with each other in the process of genome evolution.

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    Unconditional and Conditional QTL Analysis of Wheat Spike Length in Common Wheat Based on 55K SNP Array
    TANG HuaPing,CHEN HuangXin,LI Cong,GOU LuLu,TAN Cui,MU Yang,TANG LiWei,LAN XiuJin,WEI YuMing,MA Jian
    Scientia Agricultura Sinica    2022, 55 (8): 1492-1502.   DOI: 10.3864/j.issn.0578-1752.2022.08.002
    Abstract257)   HTML47)    PDF (985KB)(103)       Save

    【Objective】This study is to excavate spike length (SL)-related quantitative trait loci (QTL) with potential breeding value, explore the genetic relationship between SL and other important agronomic traits in wheat, and aim at laying a foundation for fine mapping and molecular-assisted selection breeding. 【Method】A total of 126 F7 recombinant inbred lines (RIL) constructed by crossing 20828 and SY95-71 were used in this study. The RIL population including their parents were planted in seven different environments for phenotypic evaluation: Wenjiang, Chongzhou, Ya'an of Sichuan Province in China, and Khulna in Bangladesh during 2016-2017 and 2017-2018 growing seasons. Unconditional QTL mapping was performed using a genetic linkage map constructed using the wheat 55K SNP array, and QTLs’ effects were further analyzed. Conditional QTL analysis was performed to analyze the relationship between SL and other agronomic traits including plant height (PH), spike extension length (SEL), spikelet number per spike (SNS) and thousand-kernel weight (TKW). 【Result】Thirteen QTLs controlling SL were identified using unconditional QTL mapping, and they were located on chromosomes 1A, 1D, 2B, 2D, 4B, 6D, and 7A. The LOD values ranged from 2.79 to 6.19, and the phenotypic variation rate ranged from 5.35% to 12.77%. Three stable and major QTLs (QSl-sau-2SY-2B, QSl-sau-2SY-2D.5 and QSl-sau-2SY-4B) were identified, and they explained 6.54% to 11.72%, 10.16% to 12.57%, and 5.35% to 10.92% of phenotypic variation rate, respectively. Furthermore, these three major QTLs could be also detected in multi-environment analysis. Moreover, aggregation analysis suggested that the SL of lines polymerizing the positive allels at these three major QTLs was significantly longer than that of those with any two ones or those carrying only one. Meanwhile, it was found that QSl-sau-2SY-2B had no significant effect on PH, SEL, SNS and TKW. QSl-sau-2SY-2D.5 had a significant effect on improving TKW (3.98%), but no significant effect on PH, SEL and SNS. QSl-sau-2SY-4B had a significant effect on decreasing PH (-12.28%) and SEL (-22.26%), but no significant effect on SNS and TKW. The conditional QTL analysis showed that QSl-sau-2SY-2B was independent of PH and SEL, whereas, affected by SNS and TKW. QSl-sau-2SY-2D.5 was independent of SEL, SNS and TKW, but affected by PH. QSl-sau-2SY-4B was independent of SEL and TKW, but affected by PH and SNS. 【Conclusion】In this study, three stable and major QTLs were identified for SL: QSl-sau-2SY-2B, QSl-sau-2SY-2D.5, and QSl-sau-2SY-4B, among which QSl-sau-2SY-2B may be a novel QTL independent of PH and SEL.

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    QTL Mapping of Thousand-Grain-Weight and Its Related Traits in Zhou 8425B × Xiaoyan 81 Population and Haplotype Analysis
    LinHan ZOU,XinYing ZHOU,ZeYuan ZHANG,Rui YU,Meng YUAN,XiaoPeng SONG,JunTao JIAN,ChuanLiang ZHANG,DeJun HAN,QuanHao SONG
    Scientia Agricultura Sinica    2022, 55 (18): 3473-3483.   DOI: 10.3864/j.issn.0578-1752.2022.18.001
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    【Objective】Zhou 8425B is one of the most important founder parents in China and Xiaoyan 81 is an elite cultivar with high yield and good quality. Thousand-grain weight (TGW) is an important factor that affects wheat yield. Identification of QTL associated with grain related traits from Zhou 8425B and Xiaoyan 81, and haplotype analysis of these QTL in wheat cultivars from different ecological regions would be beneficial for yield improvement by molecular marker-assisted selection.【Method】In this study, a RIL population (F8) derived from Zhou 8425B × Xiaoyan 81 was planted in Yangling during 2015 and 2016 cropping seasons to evaluate grain related traits. Using a high-density genetic map constructed by 90K SNP markers, QTL mapping of thousand-grain weight, grain length, grain width and thickness was performed under three environments. Simultaneously, the KASP markers linked to the identified QTL were developed and molecular detection was carried out among 479 wheat accessions worldwide. Moreover, haplotype analysis of target QTL was performed in 106 current wheat commercial cultivars from Yellow and Huai River Valley Winter Wheat Region selected from 479 wheat accessions.【Result】A total of 22 QTL on 8 chromosomes were detected, and the phenotypic variation explanation (PVE) ranged from 4.77% to 19.95%. Among them, 12 QTL are major QTL (PVE>10%) and Qkgw.nwafu-6B is a new QTL. QTL on chromosomes 4A, 6A, 6B, and 7D were detected in multiple environments, of which, the QTL on chromosomes 4A and 7D are same as previously reported ones. Compared to TaGW2-6A using molecular detection, both Zhou 8425B and Xiaoyan 81 carried the same allele of TaGW2. Based on haplotype result of Qkgw.nwafu-6A, Zhou 8425B and Xiaoyan 81 were placed in different groups. Therefore, Qkgw.nwafu-6A tends to be a new one. Haplotype analysis showed that there were five haplotypes for Qkgw.nwafu-6A and there were eight haplotypes for Qkgw.nwafu-6B. 6A_h1 and 6B_h6 accounted for over 20% in different ecological regions. In addition, a co-segregated KASP marker was developed for Qkgw.nwafu-6B and was significantly associated with the grain weight in the 479 wheat accessions.【Conclusion】Qkgw.nwafu-6A and Qkgw.nwafu-6B are possible new QTL associated with thousand-grain-weight, and 6A_h1 and 6B_h6 are likely favorable haplotypes. A molecular marker KASP_IWA349 co-segregated with Qkgw.nwafu-6B was developed and will be useful for marker assisted selection.

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    Effects of Hybrid Rice on Grain Yield and Nitrogen Use Efficiency: A Meta-Analysis
    LIAO Ping,MENG Yi,WENG WenAn,HUANG Shan,ZENG YongJun,ZHANG HongCheng
    Scientia Agricultura Sinica    2022, 55 (8): 1546-1556.   DOI: 10.3864/j.issn.0578-1752.2022.08.006
    Abstract253)   HTML40)    PDF (498KB)(127)       Save

    【Objective】Hybrid rice has a higher yield potential than inbred rice, but the difference in nitrogen (N) use efficiency between hybrid rice and inbred rice remains unclear. The objective of this study was to examine the effects of hybrid rice on yield and N use efficiency through meta-analysis techniques. 【Method】The peer-reviewed articles were collected, which included inbred rice as the control in comparison with a hybrid rice treatment. In total, the dataset included 56 studies involving 367 paired observations. Then, the meta-analysis was conducted to identify the response of grain yield and N use efficiency to hybrid rice as affected by hybrid type, N rate, the number of N application, soil total N content, the ratio of soil organic carbon to N, and soil texture. 【Result】Overall, the hybrid rice significantly increased rice yield (+11%) and biomass (+14%), but did not affect harvest index compared with inbred rice. Hybrid rice could improve rice yield relative to inbred rice under various N rates. However, the increase in rice yield under hybrid rice reduced with increasing N application rates. Moreover, the hybrid rice significantly increased N uptake, N physiological efficiency, and N recovery efficiency by 8.1%, 2.9%, and 3.6 units, respectively. 【Conclusion】Hybrid rice could improve yield and N use efficiency relative to inbred rice, which provided an insight to evaluate the effect of hybrid rice on grain yield and N use efficiency in China.

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    Effects of NaCl Stress on the Chlorophyll Fluorescence Characteristics of Seedlings of Japonica Rice Germplasm with Different Salt Tolerances
    ZHU ChunYan,SONG JiaWei,BAI TianLiang,WANG Na,MA ShuaiGuo,PU ZhengFei,DONG Yan,LÜ JianDong,LI Jie,TIAN RongRong,LUO ChengKe,ZHANG YinXia,MA TianLi,LI PeiFu,TIAN Lei
    Scientia Agricultura Sinica    2022, 55 (13): 2509-2525.   DOI: 10.3864/j.issn.0578-1752.2022.13.003
    Abstract252)   HTML0)    PDF (1881KB)(160)       Save

    【Objective】Chlorophyll fluorescence parameters can reflect the damage degrees and stress resistance of the plant photosynthetic machinery under salt stress. In this study, the analysis of effects of salt stress on chlorophyll fluorescence characteristics of japonica rice with different salt tolerances was performed to reveal its induced kinetic characteristics and preliminarily elucidate the mechanism of OsHCF222 and OsABCI7 regulating salt tolerance of japonica rice at seedling stage, so as to provide a theoretical foundation for screening and breeding salt-tolerant rice varieties.【Method】Eight salt-tolerant and eight salt-sensitive japonica rice germplasm accessions were used as experimental materials in this study. Leaf chlorophyll fluorescence parameters were measured for these materials after treatment using 0 mmol·L-1 or 125 mmol·L-1 NaCl for 3 or 6 days. Principal component analysis (PCA) was used to screen the key indexes for salt tolerance, and a comprehensive evaluation of japonica rice germplasm was carried out with membership functions and weighted standard deviation coefficient method. The resulting salt-tolerant and salt-sensitive germplasm were used to analyze the relative expressions of OsHCF222 and OsABCI7, two chlorophyll fluorescence related genes. 【Result】Compared with the control (CK, 0 mmol·L-1 NaCl for 3 days or 6 days), the salt stress treatment (125 mmol·L-1 NaCl 3 days or 6 days) significantly reduced the maximal fluorescence (Fm) and maximum quantum efficiency of PSII (Fv/Fm) of japonica rice germplasm. For salt tolerant germplasm accessions, the non-photochemical quenching coefficient (NPQ) and coefficient of non-photochemical quenching of variable fluorescence (qN) decreased significantly at 3 days after salt stress, while the initial fluorescence yield (Fo) increased significantly at 6 days after salt stress. The photochemical quenching coefficient (qP) and qN of the salt-sensitive germplasm accessions decreased significantly on the 3rd day after salt stress treatment, while the indexes including yield (Y), NPQ and photosynthetic electron transfer rate (ETR) decreased significantly on the 3rd and 6th day after salt stress treatment. Under salt stress, Fm, Fv/Fm, Y, NPQ and ETR were positively correlated with salt tolerance score (STS), and there were significant differences between salt-tolerant and salt-sensitive japonica rice germplasm accessions. PCA with eight chlorophyll fluorescence parameters revealed two major components, with a cumulative contribution rate of 88.018%. Five key indexes, including Fm, Fv/Fm, Y, NPQ and ETR, were selected based on the loading of each component. The 16 accessions were subsequently assigned to salt tolerant and salt sensitive groups by cluster analysis. A comprehensive evaluation value D (DCF) of chlorophyll fluorescence characteristics under salt stress was obtained by using membership function combined with the index weight method, and then the ranking of the 16 accessions was obtained. Chlorophyll fluorescence induction curves of salt-tolerant Cigalon and Bertone, salt-sensitive Xinzhu8 and Sachiminori under salt stress and CK were created using the Kinetic model. Under CK condition, the four japonica rice germplasm accessions showed similar curve shapes with a large slope and the occurrence time of P peak was basically the same. Under the salt stress treatment, peak P, peak M and the curve slope of salt-sensitive accessions decreased rapidly, while the salt-tolerant accessions still maintained high P peak and curve slope. Through quantitative real-time PCR analysis of OsHCF222 and OsABCI7 in Cigalon and Sachiminori at different times under NaCl stress, the dynamic changes and correlation between leaf chlorophyll content and five key chlorophyll fluorescence parameters, the potential role of the two genes in salt tolerance of japonica rice were preliminarily clarified. 【Conclusion】Chlorophyll fluorescence parameters of japonica rice germplasm with different salt tolerances responded differently to salt stress. Fm, Fv/Fm, Y, NPQ and ETR were closely related to salt tolerance in rice. The expression levels of OsHCF222 and OsABCI7 directly affected the salt tolerance of japonica rice germplasm at seedling stage. In salt-tolerant japonica rice, NPQ and Fv/Fm played as key indexes, while Fm might play an important role in salt-sensitive japonica rice.

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    Mechanisms Analysis on Yield Gap and Nitrogen Use Efficiency Gap of Winter Wheat in Shandong Province
    HAN ShouWei,SI JiSheng,YU WeiBao,KONG LingAn,ZHANG Bin,WANG FaHong,ZHANG HaiLin,ZHAO Xin,LI HuaWei,MENG Yu
    Scientia Agricultura Sinica    2022, 55 (16): 3110-3122.   DOI: 10.3864/j.issn.0578-1752.2022.16.004
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    【Objective】 Four planting patterns were designed based on survey data to simulate four different yield levels of winter wheat to quantify the yield gap and nitrogen use efficiency gap in Shandong province, to analyze the relationship between yield gap and nitrogen use efficiency gap, and to clarify the contribution of the environment, cultivation conditions and physiological parameters to the yield gap, so as to explore possible ways to synergistically narrow yield gap and increase resource utilization efficiency. 【Method】 This experiment was carried out in Jining, Dezhou, Yantai and Zibo in Shandong from 2016 to 2020. Four treatments were set through comprehensive management measures, such as selection of varieties, fertilizer input, planting density, and irrigation level, which were super-high yield level (SH), high-yield and high-efficiency level (HH), farmer level (FP), and basic yield level (ISP). The yield gap and nitrogen use efficiency gap between different yield levels were analyzed quantitatively to explore the influencing factors of yield gap and nitrogen use efficiency gap and the way to narrow yield gap and increase nitrogen use efficiency. 【Result】 The yield gap between the current high-yield record of wheat in Shandong and SH, SH and HH, HH and FP, FP and ISP were 2 729.1, 674.3, 1 042.9 and 4 349.8 kg·hm-2, respectively. The partial production efficiency gap of nitrogen between SH and HH, HH and FP were -13.54 and 15.67 kg·kg-1, respectively. There was a quadratic equation between the yield and the partial production efficiency of nitrogen. The contribution rate of the current uncontrollable factors (precipitation, temperature, etc.) and controllable factors (resource input, etc.) to the yield gap were 31.16% and 68.84%, respectively. The results showed that the gap of mean leaf area index (MLAI), mean net assimilation rate (MNAR), ear number per unit area (EN) and grain weight (GW) were significantly positively correlated with the yield gap between SH and HH (YG). The gap of harvest index (HI), grain number per spike (GN) and grain weight (GW) were positively correlated with the yield gap between HH and FP (YG). SH and HH treatments had higher aboveground biomass, number of ears per plant and percentage of earring-tillers than FP treatment. 【Conclusion】 At present, the yield level of winter wheat of farmers in Shandong had only achieved 64.34% of the highest recorded yield. Cultivation measures, such as optimizing fertilizer and water input, increasing the proportion of topdressing, and increasing the application of organic fertilizer and zinc fertilizer, could reduce the yield gap by 23.46%, and increase the partial production efficiency of nitrogen by 56.99%. The post-anthesis material production capacity was still the limiting factor for wheat yield improvement. However, when ensuring the light contract after anthesis, increasing the re-transportation of pre-anthesis stored dry matter to improve the harvest index was an effective measure to synergistically improve yield and nitrogen use efficiency.

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    Spatial-Temporal Variability of Soil Nutrients and Assessment of Soil Fertility in Erhai Lake Basin
    GUO YingXin,CHEN YongLiang,MIAO Qi,FAN ZhiYong,SUN JunWei,CUI ZhenLing,LI JunYing
    Scientia Agricultura Sinica    2022, 55 (10): 1987-1999.   DOI: 10.3864/j.issn.0578-1752.2022.10.009
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    【Objective】By studying the spatial-temporal variation characteristics of tobacco-planting soil nutrients in Erhai Lake Basin (ELB), the objective of grading evaluation and spatial visualization of tobacco-planting soil fertility in this region was achieved, so as to provide a scientific basis for the nutrient management, balanced fertilization, and the control of agricultural non-point source pollution of tobacco-planting areas in ELB.【Method】Based on the 964 tobacco-planting soil samples in ELB collected in 2011-2013, 2018 and 2020, this study explored the spatial-temporal variability of nutrients and regional distribution patterns by using Geostatistics, Geographic Information Systems (GIS) technology, and Fuzzy integrated fertility index method to quantify the soil fertility in tobacco-planting areas. 【Result】The average values of soil pH, soil organic matter (SOM), total nitrogen (TN), Olsen-P (AP) and available potassium (AK) of tobacco-planting soil in ELB were 7.3, 59.6 g·kg-1, 3.5 g·kg-1, 54.4 mg·kg-1, and 192.0 mg·kg-1, respectively, all of which belonging to moderate variation. Tobacco-planting soil was rich in SOM, TN, AP and AK, and the proportions of areas within the upper-middle level accounted for 85.2%, 93.8%, 94.5% and 78.8%, respectively, showing obvious variation at regional scale. The area of tobacco-planting soil fertility were graded to five levels (from high to low: I to V), which accounted for 8.4%, 25.0%, 40.3%, 23.3% and 3.0%, respectively. The pH of tobacco-planting soil was relatively alkaline in ELB, which was higher in the northern than in the southern; the highest concentrations of SOM and TN occurred in the northern and the western region; the areas with high AP concentration were distributed in patches in the northern, eastern and western region of Erhai Lake; the areas with high AK concentration were distributed in flakes in the northern and eastern of Erhai Lake. 【Conclusion】Collectively, the fertility of the tobacco-growing soil in ELB was in high level, and the high-quality soil areas above grade III were mainly distributed in the northern and eastern region. Meanwhile, the tobacco-planting soil in the northern and western Erhai Lake were rich in nitrogen and phosphorus, and there was a risk of agricultural non-point source pollution in the region.

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    Effects of Interspecific Distances on Soil Physicochemical Properties and Root Spatial Distribution of Maize-Soybean Relay Strip Intercropping System
    REN JunBo,YANG XueLi,CHEN Ping,DU Qing,PENG XiHong,ZHENG BenChuan,YONG TaiWen,YANG WenYu
    Scientia Agricultura Sinica    2022, 55 (10): 1903-1916.   DOI: 10.3864/j.issn.0578-1752.2022.10.003
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    【Objective】The purpose of this study was to explore the effects of interspecific distance on soil environment and root spatial distribution of maize-soybean intercropping, so as to provide a theoretical basis for crop roots to regulate the efficient utilization of nutrients.【Method】The field experiments were used one-factor randomized block design with 5 root interaction modes: maize-soybean intercropping spacing 30 cm (MS30), 45 cm (MS45), 60 cm (MS60), maize monoculture row spacing 100 cm (MM100), and soybean monoculture row spacing 100 cm (SS100). The changes of soil oxygen content, soil respiration rate, soil nutrient content, soil aggregate and root distribution were investigated.【Result】From dough stage (R4) to maturity stage (R6) of maize, as well as from the beginning seed (R5) to full maturity (R8) of soybean, the daily average soil oxygen content and soil respiration rate of intercropping treatment initially increased and then decreased later with the increase of interspecific distance; The soil oxygen content of maize was the highest in MS45, the lowest under MS30, while the soil respiration rate of intercropping was significantly lower than the monoculture. The soil respiration rate of soybean was the highest under MS45, which was 130.00% higher than that under SS100, while the soil oxygen content of intercropping was lower than that of monoculture. Compared with monoculture, the content of water-stable aggregates >5 mm in the soil of intercropping maize, the content of water-stable aggregates of 5-2 mm in the soil of intercropping soybean and the soil NO- 3-N were significantly increased, by 19.26%, 4.49%, and 18.07%, respectively; Among which, those contens under MS45 was the highest. During the co-growing period, compared with monoculture, the spatial distribution of maize and soybean roots under each intercropping treatment was asymmetrical, and the intercropping maize roots could extend horizontally below the space of soybean rows and grow deeper vertically. The root system of intercropping soybean was obviously inclined to the growth of soybean belt, and the total root length, root surface area, root volume and root dry weight of intercropping maize and soybean were lower than that of monoculture. After the maize was harvested, the intercropping soybean root system resumed growth and further extended in the horizontal and vertical directions. The root volume of MS45 was higher than those of monoculture. PCA analysis showed that soil nutrient content and water stable aggregate index were positively correlated with root morphological parameters.【Conclusion】Reasonable interspecific distance promoted the formation of soil large aggregates, increased soil oxygen content, improved soil aeration environment and soil nutrient, optimized the spatial distribution of crop roots, and promoted root growth and development.

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    Cloning of the Soybean Single Zinc Finger Protein Gene GmSZFP and Its Functional Analysis in SMV-Host Interactions
    ZHAO DingLing,WANG MengXuan,SUN TianJie,SU WeiHua,ZHAO ZhiHua,XIAO FuMing,ZHAO QingSong,YAN Long,ZHANG Jie,WANG DongMei
    Scientia Agricultura Sinica    2022, 55 (14): 2685-2695.   DOI: 10.3864/j.issn.0578-1752.2022.14.001
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    【Objective】The molecular mechanism underlying the resistance to soybean mosaic virus (SMV) infection in soybean is of great importance as soybean mosaic caused by SMV has become one of the major soybean disease worldwide. We have previously performed transcriptome analysis of SMV-inoculated soybean after inhibition of H2O2 production and have identified a differentially expressed C2H2-type single zinc finger protein gene, Glyma.18G003600.1, named GmSZFP. In this study, we use virus induced gene silencing (VIGS) technique to investigate the function of GmSZFP in soybean-SMV interaction, providing a foundation for further investigation of the molecular mechanism of GmSZFP in soybean-SMV interaction. 【Method】Soybean cultivar Jidou 7 and SMV strains SC-8 (susceptive) and N3 (resistance) were used as the materials in this study. Bioinformatic analysis was conducted to predict the protein domains of GmSZFP; its transcription factor activity was measured by transcriptional activation assay in yeast; the expression characteristics of GmSZFP at the transcriptional level in soybean-SMV interaction were verified by real-time quantitative PCR (qPCR); and the function of GmSZFP in soybean-SMV interaction was investigated by VIGS technique. 【Result】The CDS region of GmSZFP gene was cloned; amino acid sequence analysis and transcriptional activation assay in yeast revealed that GmSZFP is a C2H2-type zinc finger protein transcription factor with transcriptional activation activity; qPCR results showed that GmSZFP was strongly induced by SMV inoculation, and the expression pattern was different between the compatible and the incompatible combinations. The expression of GmSZFP was elevated after SMV inoculation, and then decreased in the incompatible combination, and the expression level of GmSZFP was significantly lower in the compatible combination than that in the former. Moreover, the expression level of GmSZFP was found to be reduced to the level that is similar to the level in the compatible combination that was pre-inoculated with imidazole, indicating that GmSZFP responds to SMV infestation at the transcriptional level and is regulated by H2O2; After silencing GmSZFP, we found that callose at the SMV inoculation site was greatly reduced compared to the control, and the expression of callose synthase genes GmGSL7c and GmGSL12b was reduced compared to the control, and the expression of callose hydrolase gene BG was elevated compared to the control; In addition, after GmSZFP was silenced, the virus spread outward to a distance of 2 mm at 72 h and to a distance of 3 mm at 96 h from the central source after SMV was inoculated in a small area, while the expression of SMV capsid protein (CP) gene was not detectable outside the inoculation site in control leaves; 10 d after SMV inoculation, the upper leaves (of the SMV inoculated leaves) in the GmSZFP-silenced plants showed mosaic, greening and curling symptoms, and CP gene was expressed, indicating that silencing of GmSZFP enabled SMV to transport in an unrestricted manner. 【Conclusion】GmSZFP is a canonical C2H2-type mono-zinc finger protein, and the GmSZFP gene plays a positive regulatory role in soybean resistance to SMV infection.

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    The Functional Analysis of High Mobility Group MsHMG-Y Involved in Flowering Regulation in Medicago sativa L.
    ZHANG YunXiu,JIANG Xu,WEI ChunXue,JIANG XueQian,LU DongYu,LONG RuiCai,YANG QingChuan,WANG Zhen,KANG JunMei
    Scientia Agricultura Sinica    2022, 55 (16): 3082-3092.   DOI: 10.3864/j.issn.0578-1752.2022.16.002
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    【Objective】Flowering is an important signal indicating the transformation from vegetative growth to reproductive growth and has a significant effect on plant biomass. Alfalfa is one of the upmost forage crops worldwide, its yield and quality are closely related to flowering time. The optimum harvest time for alfalfa is during the early flowering stage, which could give the highest yield and the best quality. In the current study, an alfalfa flowering related gene, Medicago sativa High Mobility Group Y (MsHMG-Y), was cloned. The gene structure and expression pattern of MsHMG-Y were studied. Function of MsHMG-Y in alfalfa flowering regulation was analyzed. This work could provide theoretical support for mechanism study underlying flowering regulation. 【Method】MsHMG-Y was cloned by homology cloning strategy and the amino acid sequence was analyzed by multiple sequence alignment. The phylogenetic tree was also constructed. qRT-PCR analysis was used to detect the expression level of MsHMG-Y in different tissues and different flowering stages. The expression pattern of MsHMG-Y under light, gibberellin (GA3), salicylic acid (SA) or methyl jasmonate (MeJA) treatment were analyzed. The phenotype of MsHMG-Y-overexpressing alfalfa was analyzed, and the expression levels of flowering activators and suppressors were also analyzed. 【Result】Phylogenetic analysis showed that MsHMG-Y has the closest relationship with MtHMG-Y in Medicago truncatula. Spatial expression pattern analysis showed that MsHMG-Y was expressed in flowers, stems and leaves, with the highest expression level in flowers and the lowest expression level in leaves in both paternal and maternal alfalfa. In paternal alfalfa with early flowering phenotype, the expression level of MsHMG-Y was the highest at early flowering stage. The highest expression level of MsHMG-Y was detected at flower bud differentiation stage in maternal alfalfa with late flower phenotype. Photoperiod analysis showed that MsHMG-Y was down-regulated after 16-hour light treatment. After 28 hours of light treatment, the expression level of MsHMG-Y was continuously lower than that in the control group, indicating that MsHMG-Y was down-regulated after light treatment. After 50 μmol·L-1 GA3, 100 μmol·L-1 SA or 100 μmol·L-1 MeJA treatment, the expression level of MsHMG-Y was up-regulated compared with the mock treatment. In detail, the expression level of MsHMG-Y was the highest at 1 h under GA3 treatment, which was 3.5 folds higher than control. Under SA treatment, the expression level of MsHMG-Y was the highest at 6 h, which was 24 folds higher than the mock treatment. The expression level of MsHMG-Y was the highest at 3 h under MeJA treatment, which was 11 folds higher than the control. These results indicated that the expression of MsHMG-Y was inducible by the above three hormones. MsHMG-Y-overexpressing alfalfa has late flowering phenotype. The expression levels of flowering activator genes were down-regulated in MsHMG-Y-overexpressing alfalfa, while the expression levels of flowering inhibitor genes were up-regulated. Among these genes, expression of flowering activator genes MsPHYA, MsGI and MsFTa1 was significantly down-regulated by 4.9 folds, 3.9 folds and 2.8 folds respectively, and the expression level of flowering inhibitor genes MsTEM and MsSVP was increased by 2.5 folds and 1.9 folds, respectively. 【Conclusion】The expression of MsHMG-Y is inducible by photoperiod and exogenous hormone treatment, including GA3, SA and MeJA. Overexpression of MsHMG-Y in alfalfa resulted in delayed flowering time. MsHMG-Y plays an important role in regulatory mechanism underlying late flowering in alfalfa.

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    Coupling Effects of N-fertilizer Postponing Application and Intercropping on Maize Photosynthetic Physiological Characteristics
    XU Ke,FAN ZhiLong,YIN Wen,ZHAO Cai,YU AiZhong,HU FaLong,CHAI Qiang
    Scientia Agricultura Sinica    2022, 55 (21): 4131-4143.   DOI: 10.3864/j.issn.0578-1752.2022.21.004
    Abstract242)   HTML46)    PDF (1046KB)(188)       Save

    【Objective】The problem for film-mulched maize in the oasis irrigation region was an advanced nitrogen (N) requirement and led to the insufficient supply of N at the late growth stages. In this study, the effects of N-fertilizer postponing application on intercropped maize photosynthetic physiological characteristics and grain yield were studied, so as to reveal the photosynthetic mechanism of intercropped maize grain yield advantage in the experimental area. 【Method】From 2019 to 2021, the maize was used as experimental materials in Hexi oasis irrigation region. The split-plot experiment design was adopted, among which pea/maize intercropping and maize monoculture were the main factors, and three N fertilizer postponing application (postponing ration 20%, 10%, and traditional practice) were the secondary factors. Then, this field experiment was used to investigate the photosynthetic physiological characteristics and yield performance of maize under N-fertilizer postponing application and intercropping pattern. 【Result】The results demonstrated that the grain yield of intercropped maize under the postponing application of 20% N-fertilizer and 10% was increased by 28.5% and 13.8%, and biomass yield by 23.8% and 12.5%, respectively, compared with traditional N management practices. Similarly, compared with traditional N management practice, the grain yield of sole maize under the postponing application of 20% N-fertilizer and 10% was also increased by 29.7% and 13.3%, and biomass yield by 19.6% and 10.3%, respectively. Compared with the monoculture maize, intercropping could increase the grain yield by 33.2%-35.1% and biomass yield by 26.8%-31.5% under the same area. Furthermore, the postponing application of 20% N-fertilizer and 10% increased the population grain yield of intercropping pattern by 27.2% and 12.9%, respectively, compared with the traditional N management practice. The results showed that intercropping pattern could increase the grain yield of maize compared with the sole pattern, and the N fertilizer postponing application also boosted the improvement of grain yield in the intercropping system compared with the traditional N management practice. During the whole growth periods, the intercropping increased the net photosynthetic rate, stomatal conductance, transpiration rate, and decreased intercellular CO2 concentration. Compared with traditional N management, the net photosynthetic rate under the postponing application of 20% N-fertilizer and 10% was increased by 12.8% and 6.0%, the stomatal conductance by 14.0% and 6.9%, and the transpiration rate by 20.5% and 9.5%, respectively, while the intercellular CO2 concentration was decreased by 29.8% and 13.1%, respectively. The SPAD value under the postponing application of 20% N-fertilizer and 10% was increased by 7.5% and 3.7%, respectively. The principal component analysis results showed that the N-fertilizer postponing application and intercropping pattern could increase the grain yield via boosting the net photosynthetic rate, the stomatal conductance, the transpiration rate, and leaf SPAD value, and decreasing intercellular CO2 concentration. 【Conclusion】N-fertilizer postponing application 20% treatment (36 kg·hm-2 N fertilizer was topdressing at maize jointing stage and 108 kg·hm-2 at 15 d post-silking stage) had the advantage of improving the photosynthetic characteristics of intercropped maize, thereby boosting the grain yield improvement.

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    Effects of Seedlings Enriched with Zinc on Cadmium Accumulations and Related Transporter Genes Expressions in Different Rice Cultivars
    JIANG XiaoTing,HUANG GaoXiang,XIONG XiaoYing,HUANG YunPei,DING ChangFeng,DING MingJun,WANG Peng
    Scientia Agricultura Sinica    2022, 55 (17): 3267-3277.   DOI: 10.3864/j.issn.0578-1752.2022.17.001
    Abstract240)   HTML53)    PDF (533KB)(139)       Save

    【Objective】 Rice seedlings enriched with zinc (Zn) is a new method to antagonize cadmium (Cd) within rice, studying the various effects and underlying mechanisms among different rice cultivars is useful to provide a basis for the application of this method. 【Method】 Hydroponic and pot experiments were conducted to test the effects of the Zn enrichment in four cultivars including the Wuyunjing21, Zhejingyou1578, Huanghuazhan, and Huiliangyousimiao. Dynamics of Zn accumulation in different cultivars, and variations of Cd uptake and transport in rice tissues were investigated. Furthermore, the expressions of the Cd-related transporter genes of the root were analyzed to explore the underlying mechanisms responsible for the various effects in different cultivars. 【Result】 Results showed that the Zn cultivation didn’t affect the growth of all rice seedlings. Zn accumulations varied obviously among different cultivars, the Zhejingyou1578 had the highest Zn level (230 μg Zn per plant), followed by the Wuyunjing21 (124 μg Zn per plant), the Huanghuazhan and Huiliangyousimiao had the low levels (85.1-95.0 μg Zn per plant). Zn enrichment greatly influenced the expression of Cd-related transporters in the Zhejingyou1578, the OsZIP7 was down-regulated by 48.7% and OsZIP1 was up-regulated by 81.3%. The expressions of the OsIRT1 and OsZIP7 in the Wuyunjing21 were also down-regulated by 35.9% and 35.0%, respectively, and the OsZIP1 was up-regulated by 31.1%. However, the Cd-related transporters in the Huanghuazhan and Huiliangyousimiao were insensitive to Zn enrichment. As a result, Zn enrichment significantly reduced Cd concentrations in the root and shoot by 26.7% and 36.7% of the Wuyunjing21, and 32.0% and 40.0% of the Zhejingyou1578 with a 12.0% inhibition on the Cd transport, respectively. Furthermore, brown rice Cd were reduced by 37.5%, 36.7% and 25.3% in the Wuyunjing21, Zhejingyou1578, and Huanghuazhan, respectively, while no difference occurred in the Huiliangyousimiao, revealing various effects on reducing Cd among different cultivars induced by the Zn enrichment. Correlation analysis showed that the brown rice Cd was negatively correlated with the shoot Cd which was negatively correlated with the root and shoot Zn, revealing a significant antagonism between Zn and Cd within rice. However, the root and shoot Zn were negatively correlated with the OsZIP7 and OsIRT1 and positively correlated with the OsZIP1 expression, indicating that the Zn enrichment within seedlings influenced the brown rice Cd mainly through regulating the expressions of the OsZIP1, OsZIP7 and OsIRT1. 【Conclusion】 The regulations on Cd-related transporters through Zn enrichment were varied among different cultivars, and the Zhejingyou1578 and Wuyunjing21 were more sensitive, so that the reductions of brown rice Cd were higher than other cultivars.

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    Construction of High Density Genetic Map for RIL Population and QTL Analysis of Heat Tolerance at Seedling Stage in Rice (Oryza sativa L.)
    LIU Jin,HU JiaXiao,MA XiaoDing,CHEN Wu,LE Si,JO Sumin,CUI Di,ZHOU HuiYing,ZHANG LiNa,SHIN Dongjin,LI MaoMao,HAN LongZhi,YU LiQin
    Scientia Agricultura Sinica    2022, 55 (22): 4327-4341.   DOI: 10.3864/j.issn.0578-1752.2022.22.001
    Abstract238)   HTML78)    PDF (5241KB)(150)       Save

    【Objective】 With global warming, high temperature has an increasing impact on food crop safe. Excavation of heat tolerance gene resources is the most direct green ecological method to cultivate new varieties of heat resistance and eliminate the harm of high temperature, which also the basis for clarifying the physiological, biochemical and molecular genetic mechanism of heat tolerance.【Method】Establishing the identification and evaluation method of heat tolerance at seedling stage, a set of RIL populations was structured from the extreme heat-tolerance Ganzaoxian58(GZX58) and heat-sensitive Junambyeo (JNB), and then the high density genetic map was constructed using genotyping by resequencing technology. To converting SNP information into Bin genotype of the RIL population using sliding window method, which predicting the recombination breakpoints on the chromosomes, finally a high density BinMap genetic map was constructed. Based on the genotype and phenotype data of the 171 lines, QTL mapping of the high temperature seedling survival rate (HTSR) and heat tolerance class (HTC) was performed by ICIM method of the QTL IciMapping software.【Result】A high-density genetic map containing 3 321 Bin markers was constructed, the number of Bin markers for each chromosome between 159 and 400, the average physical distance two markers was about to 106 kb; heat tolerance of the parents and RIL populations was identified by stepwise heat stress at seedlings stage, there have a significant negative correlation between HTSR and HTC, in addition, there has a significant positive correlation between HTSR and indica gene frequency (Fi), which the higher of the Fi, the heat tolerance is better; the bi-modal continuous distribution of phenotype traits from the RIL population showed that the heat tolerance is regulated by few major QTL. A total of 12 QTL controlling with heat tolerance at seedling stage, there have 8 and 4 QTL regulating for HTSR and HTC, respectively. There has a significant genetic overlap from HTSR and HTC, qHTS2, qHTS7 and qHTS8, three major QTL cluster play an important role in regulating the heat tolerance at seedling stage. Among these QTL, qHTS7 was a novel major QTL cluster, which has a strong effect on enhancing the heat resistance at seedling stage. 【Conclusion】 We constructed a high density genetic linkage map containing 3 321 Bin markers, which be used to analyzed the heat tolerance gene from the GZX58 at seedling stage, there have three key QTL cluster identified associated with the heat tolerance, a novel QTL cluster qHTS7 was discovered, efficient acquisition of target segments and candidate genes based on high-density genetic mapping, eight key candidate genes were selected by bioinformatics for regulation of the heat tolerance.

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    Screening of Core Markers and Construction of DNA Fingerprints of Semi-Waxy Japonica Rice Varieties
    ZHAO ChunFang,ZHAO QingYong,LÜ YuanDa,CHEN Tao,YAO Shu,ZHAO Ling,ZHOU LiHui,LIANG WenHua,ZHU Zhen,WANG CaiLin,ZHANG YaDong
    Scientia Agricultura Sinica    2022, 55 (23): 4567-4582.   DOI: 10.3864/j.issn.0578-1752.2022.23.001
    Abstract237)   HTML60)    PDF (2482KB)(171)       Save

    【Objective】 A set of variety DNA fingerprint identification system based on the core markers of genes regulating rice important traits was constructed, which will establish a foundation for strengthening the germplasm management and protection of the mainly promoted semi-waxy japonica rice varieties with high eating quality.【Method】 34 semi-waxy japonica rice varieties mainly cultivated in Jiangsu, Zhejiang and Shanghai were used as the test materials. The key differential sequence sites in genes regulating rice important traits were screened and core SNP or InDel markers were developed through multiple methods such as polymorphism testing of existing markers, gene sequence alignment from public databases and genome resequencing. SNP markers were developed into simple PCR markers based on electrophoretic bands by As-PCR technology. Genotype information was obtained by electrophoretic band characterization and type analysis, and the DNA fingerprint database of the semi-waxy japonica rice varieties was constructed..【Result】 54 core markers derived from 40 key genes regulating rice important traits were obtained, including 18 SNP and 36 InDel markers; 155 characteristic and effective bands were identified by 54 markers in the tested rice varieties, which were transformed into 155 0/1 data sites. The DNA fingerprint database of each variety was established and could distinguish it from all tested varieties. Genetic diversity analysis showed that the variation range of genetic similarity among varieties was 0.47-0.90, among which the lowest similarity coefficient was detected between Nanjing 7718 and Suxiangjing 100, while the highest similarity coefficient was detected between Nanjing 9308 and Nanjing 9036, among which there were 8 differential data sites. Genetic relationship analysis indicated that 34 varieties were divided into 6 branches, of which Nanjing 7718 was an independent branch, suggesting it has a distant relationship from other varieties. Further verification of the identification effect of core markers showed that the set of markers could effectively distinguish 14 new semi-waxy japonica rice varieties. The cluster diagram showed that they were distributed in three groups of Ⅱ, Ⅲ and Ⅳ, confirming the differences of genotype information among varieties; using this set of markers, the authenticity of an unknown semi-waxy rice variety was also identified. According to genotype and cluster analysis, it was determined as Nanjing 9108.【Conclusion】 After optimization and screening, 54 core markers that could accurately distinguish all the tested semi-waxy japonica varieties were obtained, and developed into simple PCR markers detected by electrophoresis. Using this set of marker combinations, the DNA fingerprints of 34 semi-waxy japonica varieties in Jiangsu, Zhejiang and Shanghai were constructed.

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    Integration of Agricultural Machinery and Agronomic Techniques for Crop Nutrient Management in China
    MI GuoHua,HUO YueWen,ZENG AiJun,LI GangHua,WANG Xiu,ZHANG FuSuo
    Scientia Agricultura Sinica    2022, 55 (21): 4211-4224.   DOI: 10.3864/j.issn.0578-1752.2022.21.009
    Abstract234)   HTML44)    PDF (1489KB)(238)       Save

    The efficient nutrient management is essential for agricultural green development. With the increase of farm land scale and the development of agricultural mechanization, the mismatch between agricultural machinery and agronomy in nutrient management becomes increasingly obvious. There is a requirement to coordinate agronomic techniques and machinery operation. This paper analyzed the current situation and improvement direction in nutrient management techniques and agricultural machinery in the cropping system of spring maize in northeast China, winter wheat-summer maize in north China, and rice planting system in south China. It is indicated that efficient fertilizer application technology needs suitable fertilizer application machinery as guarantee, new fertilizer products need new fertilizer application machinery, changing cultivation and tillage methods generates new demand for agricultural machinery, and fertilizer application mechanization to be upgraded by using information and automatic intelligent techniques. At the same time, the fertilizer products and fertilizer application technology innovation need to take into consideration of the feasibility of mechanization. This paper described the research progress of starter fertilizer, synchronized fertilizer application and sowing technology, and straw mulching strip tillage technology in maize, within-season mechanized fertilizer application technology in wheat, mechanized side-depth fertilizer application technology in rice, and mechanized variable fertilizer application technology in China. The suggestions were provided to enhance the integration of agricultural machinery and agronomic technology, so as to upgrade the level of nutrient management of field crops.

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    Effects of Reducing Nitrogen Application on Leaf Stay-Green, Photosynthetic Characteristics and System Yield in Maize-Soybean Relay Strip Intercropping
    LI YiLing,PENG XiHong,CHEN Ping,DU Qing,REN JunBo,YANG XueLi,LEI Lu,YONG TaiWen,YANG WenYu
    Scientia Agricultura Sinica    2022, 55 (9): 1749-1762.   DOI: 10.3864/j.issn.0578-1752.2022.09.005
    Abstract233)   HTML0)    PDF (576KB)(153)       Save

    【Objective】The aim of this study was to explore the characteristics of leaf green retention, photosynthesis and system yield of maize and soybean under different planting modes and nitrogen (N) application levels.【Method】The effects of planting methods (maize monoculture (MM), soybean monoculture (SS), maize intercropping (IM), soybean intercropping (IS)) and N application levels (0 N application (NN), reduced N application (RN: 180 kg N·hm-2) and constant N application (CN: 240 kg N·hm-2)) on leaf stay-green, photosynthetic characteristics, dry matter accumulation and system yield of maize and soybean leaves were studied by field positioning experiment.【Result】The maize yield increased with the increase of N application, and the soybean yield increased first and then decreased with the increase of N application; Under RN, the seed dry matter accumulation of IM was the largest, the total yield of maize-soybean intercropping system was the highest, and the system productivity index (SPI) was the largest too. Under intercropping, the leaf green period of each crop was longer, the photosynthetic characteristics were more stable than that of monoculture, and better than that of monoculture at seed formation stage; Under all N application levels, the percentage of green leaves under intercropping treatment was significantly higher than that under monoculture. The maximum green leaf attenuation rate of IM appeared 7 d, 5 d and 1d later than that of MM, respectively, while IS was 7 d, 0 d and 11 d later than SS, respectively. Compared with monoculture, the intercropping could significantly reduce the average attenuation rate of maize leaves, prolong the days of maximum attenuation rate and reduce the attenuation degree of green leaves. The photosynthetic rate of each crop was higher under intercropping than monoculture, and the reduced N application was higher than the constant N application. At R2 stage, the photochemical quenching coefficient (QP) under IM was 12.78% higher than that under MM, and the non-photochemical quenching coefficient (NPQ) was 21.30% lower; NPQ decreased with the increase of N application level, while the ratio of RN to NN decreased by 17.11%. The fluctuation range of SPAD value of intercropping was weaker than that of monoculture, and showed a stable upward trend. In maize R2 stage, IM was 34.52% higher than MM; In soybean R2 and R6 stage, IS was 10.39% and 29.48% higher than SS, respectively, and the SPAD value of RN was the highest. At R2 stage, IMRN was 17.46% higher than IMNN, and MMRN was 35.02% higher than MMNN; in soybean R6 stage, ISRN was 7.71% and 6.67% higher than that of ISNN and ISCN, and SSRN was 10.03% higher than that of SSCN.【Conclusion】Under reduced N application condition, the maize-soybean intercropping significantly prolonged the green holding period of leaves; After flowering, the photosynthetic rate of leaves, the function of PS Ⅱ photosynthetic mechanism and chlorophyll remained at a high level were more stable than that of monoculture, and the accumulation of seed dry matter was enhanced, which gave full play to the production potential of maize and increased the yield of soybean, so that the total yield of intercropping system was significantly increased.

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    Screening and Functional Analysis in Heat-Tolerance of the Upstream Transcription Factors of Pepper CaHsfA2
    LIU RuiYao,HUANG GuoHong,LI HaiYan,LIANG MinMin,LU MingHui
    Scientia Agricultura Sinica    2022, 55 (16): 3200-3209.   DOI: 10.3864/j.issn.0578-1752.2022.16.011
    Abstract231)   HTML31)    PDF (2002KB)(131)       Save

    【Background】 Pepper is widely cultivated as a vegetable around the world. With the increasing frequency of extreme high temperature weather in recent years, the heat stress has become one of the main environmental factors affecting pepper productivity, due to its feature of warm-prone but heat-sensitive. Therefore, it is very important for pepper production to clarify its mechanisms supporting heat-tolerance and then to develop pepper varieties with heat tolerance. 【Objective】 Since the heat shock transcription factor HsfA2 plays important roles in plant heat tolerance, the upstream transcription factors of pepper CaHsfA2 were screened and functionally analyzed in heat-tolerance in this study, in order to provide the theoretical basis for further understanding the mechanisms of heat tolerance of pepper. 【Method】 The 955 bp promoter sequence upstream of start codon of CaHsfA2 was used as the bait, the yeast one-hybrid (Y1H) technology was applied to screen the upstream transcription factors of CaHsfA2, and their interactions were checked by Y1H point-to-point hybridization, dual-luciferase reporter system (Dual-Luciferase), and LUC assay (LCA). For the candidate upstream transcription factors of CaHsfA2, their dynamic expression under heat stress in pepper heat-tolerant line R9 were analyzed by qRT-PCR technology; the subcellular localization were fulfilled through the transient gene expression technology, and its functional analysis in heat tolerance were performed by using the virus-induced gene silencing technology (VIGS). 【Result】 CaBES1 was identified as the candidate upstream transcription factor of CaHsfA2, and their interactions were confirmed. By the analysis of Dual-Luciferase system and CaHsfA2 expression in CaBES1-silenced pepper plants, it was suggested that CaBES1 negatively regulated the transcription of CaHsfA2. The result of subcellular localization showed that CaBES1 was expressed in both cell membrane and nucleus. After heat stress treatment, the fluorescence signal in the nucleus was enhanced, which was consistent with the property of CaBES1 transferring from cytoplasm to nucleus when it performed its biological functions. By dynamic expression pattern analysis, under heat stress, the expression level of CaBES1 decreased firstly and then increased, which also indicated that CaBES1 could respond to heat signal and laid a foundation for the further functional study in heat tolerance. After CaBES1 was silenced in pepper, by comparing the phenotype, relative electrical conductivity and chlorophyll content of silenced plants and control plants, it was inferred that silencing of CaBES1 increased the expression of CaHsfA2 and enhanced the heat tolerance of pepper. 【Conclusion】 CaBES1 inhibited pepper heat tolerance by negatively regulating the expression of CaHsfA2.

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    Effects of High Temperature Stress in Different Periods on Dry Matter Production and Grain Yield of Summer Maize
    ZHANG Chuan,LIU Dong,WANG HongZhang,REN Hao,ZHAO Bin,ZHANG JiWang,REN BaiZhao,LIU CunHui,LIU Peng
    Scientia Agricultura Sinica    2022, 55 (19): 3710-3722.   DOI: 10.3864/j.issn.0578-1752.2022.19.003
    Abstract230)   HTML0)    PDF (586KB)(168)       Save

    【Objective】 Frequent, recurrent and prolonged high temperature stress had significant effects on grain yield of summer maize in Huang-Huai-Hai region. In this study, we investigated the effects of high temperature stress at the V12 stage and VT stage on leaf photosynthetic characteristics, carbon assimilate accumulation, distribution and grain yield of maize varieties with different heat tolerance. 【Method】 In this study, heat resistant maize variety Zhengdan 958 (ZD958) and heat sensitive maize variety Xianyu 335 (XY335) were used as materials. The normal temperature treatments (day 32℃12 h /night 22℃12 h) were set as the control at the same time. High temperature greenhouse equipped with automatic temperature and humidity control facilities was used to simulate the effect of natural field high temperature, the high temperature stress treatments (day 38℃12 h/night 28℃12 h) were set at V12 and VT stage, respectively. The dynamic characteristics of leaf area index (LAI), carbon metabolism enzyme activities, photosynthetic rate and carbon assimilate accumulation and allocation were compared after high temperature stress, aimed to determine the response mechanism of dry matter production performance and grain yield to high temperature stress. 【Result】 After high temperature stress, LAI, carbon metabolism enzyme activities, net photosynthetic rate and dry matter accumulation of two cultivars were significantly decreased. LAI, RuBP carboxylase activity, PEP carboxylase activity, net photosynthetic rate and dry matter accumulation of ZD958 and XY335 decreased by 2.98%-4.21%, 40.38%-54.46%, 16.88%-30.60%, 18.14%-25.49%, 12.83%-19.38% and 3.80%-5.07%, 56.56%-76.16%, 26.33%-33.66%, 22.37%-34.62%, 22.07%-26.72%, respectively. The decrease range of high temperature stress in VT stage was larger than that in V12 stage. After high temperature stress, transpiration rate of summer maize leaves increased, while leaf water use efficiency decreased significantly. Under high temperature stress, 13C assimilation of ZD958 and XY335 decreased by 18.48% and 22.82%, respectively, and the proportion of 13C assimilation in grains decreased. The high temperature stress significantly decreased grain number per spike and grain yield, although 1000 grain weight increased slightly. Compared to the optimum temperature, after V12 high temperature stress, the grain number per spike and yield of ZD958 decreased by 62.53% and 45.87%. After VT high temperature stress, grain number per spike and yield decreased by 70.53% and 66.89%. After V12 high temperature stress, the grain number per spike and yield of XY335 decreased by 70.50% and 62.87%. After VT high temperature stress, grain number per spike and yield decreased by 85.41% and 80.61%. The decrease range of high temperature stress in VT stage was larger than that in V12 stage, and XY335 decreased more than ZD958. 【Conclusion】 The high temperature stress reduced LAI, RuBP carboxylase and PEP carboxylase activities, and significantly reduced photosynthetic rate and dry matter production performance of summer maize. Under high temperature stress, the grain number per spike decreased significantly, which inhibited the transportation of carbohydrate from leaf and stem to grain, resulting in lower grain yield. The effects of high temperature stress on dry matter performance and grain yield of summer maize in VT stage was significantly greater than that in V12 stage. The decrease of heat sensitive variety XY335 was significantly greater than that of heat resistant variety ZD958 in two periods.

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    Cloning and Functional Analyses of MsCIPK2 in Medicago sativa
    SU Qian,DU WenXuan,MA Lin,XIA YaYing,LI Xue,QI Zhi,PANG YongZhen
    Scientia Agricultura Sinica    2022, 55 (19): 3697-3709.   DOI: 10.3864/j.issn.0578-1752.2022.19.002
    Abstract228)   HTML57)    PDF (5750KB)(92)       Save

    【Objective】 CIPKs are a group of important protein kinase involved in signaling pathway of plant in response to stress. They can form CBL-CIPK complex with CBL, to activate the expression of related responsive genes to cope with various abiotic stresses in cells. Exploration and study on the molecular mechanism of MsCIPK genes in alfalfa in response to abiotic stress will help to reveal the biological basis of stress resistance in alfalfa, and to provide new gene resources for alfalfa breeding with enhanced stress resistance. 【Method】 The MsCIPK2 gene was cloned by using PCR, the sequence was analyzed by bioinformatics tools, and the expression level of MsCIPK2, MsCBL2, MsCBL6, MsCBL7 and MsCBL10 genes in various tissues were analyzed by using qRT-PCR. The pCAMBIA1302-GFP-MsCIPK2 vector was transiently expressed in tobacco leaf epidermal cells, and the subcellular localization was observed under laser confocal microscope. Yeast two-hybrid assay was used to analyze interaction between MsCIPK2 and four MsCBLs proteins. Agrobacterium rhizogenes was used to generate alfalfa hairy roots over-expressing MsCIPK2. qRT-PCRs were used to analyze the expression levels of related genes in transgenic hairy root lines. 【Result】 The coding sequence of MsCIPK2 gene was obtained by using PCR, and it is 1 230 bp in length, encoding 409 amino acids. The deduced MsCIPK2 protein contained typical ATP binding site, activation loop, NAF motif and PPI motif as for the CIPK family genes. The expression level of MsCIPK2 gene was the highest in roots, and the lowest in the flowers of alfalfa. Subcellular localization results showed that MsCIPK2 protein was localized in the endoplasmic reticulum. Yeast two-hybrid assays showed that MsCIPK2 protein interacted with MsCBL2, MsCBL6, MsCBL7 and MsCBL10 proteins, showing stronger interaction with MsCBL10 than with other MsCBLs. The expression levels of MsCBL2, MsCBL6, and MsCBL10 were the highest in roots of alfalfa, and the expression level of MsCBL7 was the highest in pods. qRT-PCR results showed that the expression levels of abiotic stress-associated genes ATPase, P5CS, CYP705A5, COR47, HAK5 and RD2 were significantly up-regulated in hairy roots over-expressing MsCIPK2. Under the treatment of 200 mmol·L-1 NaCl and 20% PEG, when compared with the control hairy root line, hairy roots over-expressing MsCIPK2 had lower MDA content, and higher POD activity, proline content and soluble sugar content. 【Conclusion】 MsCIPK2 can interact with CBL protein, and responded to salt and drought stress in roots of alfalfa. Over-expression of MsCIPK2 can improve salt and drought stress resistance in alfalfa, and MsCIPK2 can be used as candidate gene for alfalfa breeding with improved abiotic stress resistance.

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    SCAR-PCR Rapid Molecular Detection Technology of Heterodera zeae
    CUI JiangKuan,REN HaoHao,CAO MengYuan,CHEN KunYuan,ZHOU Bo,JIANG ShiJun,TANG JiHua
    Scientia Agricultura Sinica    2022, 55 (17): 3334-3342.   DOI: 10.3864/j.issn.0578-1752.2022.17.006
    Abstract228)   HTML27)    PDF (1409KB)(77)       Save

    【Objective】 Corn cyst nematode (Heterodera zeae) is one of the sedentary semi-endoparasitic nematode of Heterodera spp., infects the roots of various gramineae crops. The occurrence and spread of H. zeae will pose a serious threat to corn yield production. The objective of this study is to establish the rapid and accurate molecular detection system for H. zeae from the related cyst nematode species, which will lay a technical foundation for the monitoring, early warning and prevention and control of H. zeae.【Method】 A total of 20 cyst nematode populations of H. zeae related species were collected as the nematode samples, from Henan, Hebei, Gansu, Shandong, Hunan, Guangxi and Beijing. Thirteen random primers containing 10 bases were selected, and RPAD technique was used to analyze the polymorphism of the tested nematode samples. The specific RPAD fragment was screened and transformed to SCAR-PCR primers of H. zeae. PCR was used to test the accuracy of specific primers for H. zeae and the stability, sensitivity and effectiveness of the detection technology system.【Result】 By comparative analysis of the RAPD results, one specific fragment of 468 bp was produced by primer OPA03. The fragment was recovered for sequencing. According to the fragment sequencing information, a pair of specific primers HzF1/HzR1 was designed. The specific primers HzF1 and HzR1 specificity test results showed that, one 393 bp specific fragment was amplified from H. zeae, no target bands were amplified in the other 16 populations of 5 related Heterodera spp. species (H. avenae, H. filipjevi, H. glycines, H. elachista and H. schachtii) and 4 populations of other species (Aphelenchoides besseyi, Ditylenchus destructor, Pratylenchus neglectus, P. coffeae). Furthermore, the 393 bp specific fragment was also amplified from the 6 related Heterodera spp. species mixed DNA. Meanwhile, there were no target bands when the mixed population without H. zeae. The system realized the accurate and stable detection of H. zeae, and the sensitivity and practical range of the established rapid detection technology system were tested. The results showed that the detection system was sensitive to single cyst and single 2nd stage juvenile (J2) of H. zeae. The minimum detection thresholds were 1/2 000 of single cyst or 1/80 of single J2, respectively.【Conclusion】 The SCAR-PCR rapid molecular detection technique established in this study can be used for the rapid detection of single samples and mixed populations of H. zeae. It has sensitive detection ability for both the cysts and the J2 of H. zeae, with strong primer specificity, convenient and stable detection method and high sensitivity.

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    Overview of Soil Survey Works in Main Countries of World
    WeiLi ZHANG,H KOLBE,RenLian ZHANG,DingXiang ZHANG,ZhanGuo BAI,Jing ZHANG,HuaDing SHI
    Scientia Agricultura Sinica    2022, 55 (18): 3565-3583.   DOI: 10.3864/j.issn.0578-1752.2022.18.008
    Abstract226)   HTML32)    PDF (549KB)(182)       Save

    The reviewing soil surveys and soil investigations in different countries shows that in order to understand the soil resources and soil quality, the soil surveys and investigations carried out by different countries since the end of the 19th century can be divided into four categories, namely: survey for soil classification, investigation and evaluation of farmland fertility, testing of soil chemical properties for fertilizer recommendation and soil investigations related to environmental issues. Among the four categories, soil classification is the earliest and the most widely implemented survey works carried out in the world. Main purpose of the classification survey is to clarify the differences in soil types and their spatial distributions caused by various soil formation processes. Since soil formation processes under natural conditions can reach tens of thousands of years, the main outputs of the classification survey—the soil maps and the records of soil profiles, expressing the physicochemical properties of various soil types, have a long timeliness and are widely used in various research areas. After the completion of nation-wide soil classification surveys in the last century in developed countries, the updated survey was not conducted in these countries. In the second national soil survey in China, large-scale soil maps covering the whole country were completed by relatively higher profile sampling density. The physicochemical properties of 100 000 soil profiles, representing different soil types, were also recorded. Both the map scale and the richness of soil profile data from the survey surpassed the outputs from classification surveys in many developed country. Soil classification data obtained from this survey are valid for a long time to different disciplines and sectors. In order to meet needs for easy-to-understand farmland fertility grades by land management sectors and farmers, investigation and evaluation of farmland fertility have been carried out in Central European countries, where per capita arable land resources have been in shortage. Through high-density profile samplings, soil fertility evaluation for each farmland plot with an independent cadastral code was carried out. An officially certified fertility grades in percentile index and the records of soil profiles were established and archived for each plot. The investigation results have been widely used in farmland management, taxation, agricultural subsidies, farmland leasing, trading, lending, insurance and other sectors, and have become the indispensable and centennial basic information for farmland quality. China's per capita arable land is much less than that of Central European countries, but so far there has been still in shortage of soil fertility data for farmland management. For preservation of arable land resources with high fertility and ensure food safety, it is essential and also urgent to establish precise and reliable fertility archives for each farmland plot in China. Also more efficient investigation and evaluation approaches, which are compatible with China's economic and social condition should be developed. The review of testing soil chemical properties to make fertilizer recommendation shows that such testing has been incorporated into the technical supporting system for best farming management practices in the developed countries. To improve farmers' fertilization techniques, it is more important to establish an efficient technical supporting system and maintain its running, in comparison to nation-wide soil nutrient census of farmland. In the past, there was continuous weakening of applied researches and extension works for fertilization technological chain from basic research to farmers' application. Due to inadequate research works, the technical indexes for fertilization, that should be differentiated to and compatible with the various regional soil and climate conditions and hence easy to be followed by farmers of different regions, have not been issued yet in China. Also the intelligent tools that can reach and provide targeted guidance to farmers were not available. Unbalanced and excessive fertilization was common in vegetable, fruit and other cash crop growing area, which accounted for 23.6% of the total cropping area in China. This resulted in reduction of crop yield and quality as well as benefit of farmers and also leaded to agricultural non-point source pollution. Making up for the shortcomings in the technical supporting system has become the key to improve both crop yield and soil fertility. Since the end of the last century, soil investigations related with environment issues have been carried out in different countries. Main purposes of these investigations are to clarify the status of environmental pollution and changing, to develop control strategy and to check effects of countermeasures. With the quick progresses of GIS-, GPD-, RS- and big data techniques, the traditional mapping approaches have be replaced by digital soil mapping techniques. An exact defining of investigation objectives and a comprehensive reviewing of relevant research progress as well as available auxiliary data are essential for drafting sampling design and achieving investigation tasks finally.

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    Effects of Intercropping with Different Maturity Varieties on Grain Filling, Dehydration Characteristics and Yield of Spring Maize
    XIAO ShanShan, ZHANG YiFei, YANG KeJun, MING LiWei, DU JiaRui, XU RongQiong, SUN YiShan, LI WeiQing, LI GuiBin, LI ZeSong, LI JiaYu
    Scientia Agricultura Sinica    2022, 55 (12): 2294-2310.   DOI: 10.3864/j.issn.0578-1752.2022.12.003
    Abstract224)   HTML46)    PDF (1414KB)(118)       Save

    【Objective】In view of the high grain moisture content during the maize harvest period in high latitude and cold areas of China, it restricts the efficient promotion and application of mechanical grain harvesting technology. In this study, the maize varieties with different maturities were intercropped according to a certain proportion under field conditions, in order to clarify the regulating effects of intercropping at different maturity on grain filling, dehydration characteristics and yield of spring maize.【Method】Maize varieties of Zhengdan 958 (ZD958), Xianyu 335 (XY335) and Yinongyu 10 (YNY10) with different maturities were used as experimental materials, two-factor randomized block design was applied to set up the intercropping between varieties with longer growth period (LGPV) and varieties with shorter growth period (SGPV), that is, ZD958 and YNY10 intercropping (Z‖Y), and XY335 and YNY10 intercropping (X‖Y). Based on the above main treatment, six kinds of intercropping width (line number) ratios, namely 6﹕6, 4﹕4, 2﹕2, 1﹕1, 0﹕1 and 1﹕0, were designed to compare and analyze the changes of maize grain filling, dehydration characteristics and yield under different treatment combinations.【Result】For LGPV, with the decrease of the intercropping ratio, the moisture content of grains in the physiological maturity and harvest phases decreased. The average dehydration rate and total dehydration rate of grains before and after physiological maturity showed a trend of acceleration, and the average filling rate (Gmean), the maximum grain filling rate (Gmax), and the grain weight at which the filling rate reached the maximum (Wmax) gradually increased; The number of days required for the maximum filling rate (Tmax) and the active grain-filling period (D) gradually shortened, and grain yield and 100-kernel weight increased significantly (P<0.05). In response to the decline of intercropping ratios, it was showed that SGPV increased in grain moisture content and decreased in dehydration rate during the physiological maturity period and harvest period, while Gmean, Gmax, and Wmax continued to decreased, and Tmax and D were slightly extended. Although yield and 100-kernel weight showed a downward trend for SGPV, but the variation did not reach a significant level. At the same time, the average grain moisture content of the intercropping compound population at the harvest period was significantly lower than that of the LGPV monocropping. The percentage of grain moisture content decline were 6.44%-7.29% for Z‖Y-(6﹕6-1﹕1) and 4.30%-4.75% for X‖Y-(6﹕6-1﹕1) on 2-year means. In terms of average grain yield to intercropping compound population, the grain yield increased with the decrease of intercropping ratios. Moreover, compared with the SGPV YNY10 monocropping, the average grain yield for Z‖Y-(6﹕6-1﹕1) and X‖Y-(6﹕6-1﹕1) increased by 5.12%-6.49% and 1.87%-2.96% on 2-year means, respectively and the increase was obvious under Z‖Y treatment.While the average grain yield of Z‖Y and X‖Y treatments was not significantly different from that of longer growth period (LGPV) monocropping.【Conclusion】Under dense planting conditions, the intercropping with different maturity maize varieties significantly promoted the increase of maximum grain filling rate and grain weight with shortening of active grain filling period and accelerating total grain dehydration rate of LGPV, effectively reduced the average grain moisture content of field composite population at harvest time, and realized the coordinated development of high and stable yield, and efficient dehydration of maize grains.

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    Maize Transcription Factor ZmEREB93 Negatively Regulates Kernel Development
    PANG HaoWan,FU QianKun,YANG QingQing,ZHANG YuanYuan,FU FengLing,YU HaoQiang
    Scientia Agricultura Sinica    2022, 55 (19): 3685-3696.   DOI: 10.3864/j.issn.0578-1752.2022.19.001
    Abstract222)   HTML51)    PDF (4112KB)(123)       Save

    【Objective】 Maize, a kind of crucial crop, is widely used in food supply, livestock feed, and industry. AP2/EREBP (APETALA2/ethylene response element-binding protein) transcription factor (TF) plays an important role in plant growth, development, and stress response. Previous study showed that ZmEREB93 might regulate seed size as a target gene of ZmBES1/BZR1-5 TF. ZmEREB93 was cloned and used to analyze its expression pattern and function, which lays foundation to clarify the function and mechanism of ZmEREB93 regulating seed size. 【Method】 The full length of ZmEREB93 was cloned from maize inbred line B73 by PCR. The characters of nucleotide and amino acid sequences were analyzed by informatic methods. Subsequently, the tissue expression specificity of ZmEREB93 was analyzed via quantitative real time PCR (qRT-PCR). The expression vector in plant and yeast was constructed and used for subcellular localization and transcription activation assay, respectively. ZmEREB93 was transformed into Arabidopsis mediated by agrobacterium transformation. The seed phenotype of transgenic lines was analyzed. Finally, the potential target genes of ZmEREB93 were screened by chromatin immunoprecipitation sequencing (Chip-seq) and co-expression analysis, and further confirmed by yeast one hybrid (Y1H). 【Result】 The ZmEREB93 gene was cloned by PCR. Sequence analysis showed that ZmEREB93 had no intron and a 618 bp ORF, encoding 205 amino acids with a highly conserved AP2 domain and belongs to the ERF subclade of AP2 family. The results of qRT-PCR showed that the ZmEREB93 gene highly expressed in kernels of 15 and 25 days after pollination (DAP), and slightly expressed in stem and root, but did not express in tassel, silk and bract. The expression level of ZmEREB93 was the highest in 25 DAP kernels reached 11 times of that in 15 DAP kernels. The results of transcriptional activation and subcellular localization assay exhibited that ZmEREB93 protein had no transcriptional activation activity in yeast cells and was localized in the nucleus, respectively. Compared to wild type, the seeds of transgenic lines were significantly smaller and showed lower thousand-seed-weight. Chip-seq and co-expression analysis suggested that the Zm00001d013611, Zm00001d006016, Zm00001d027448 and Zm00001d03991 genes were candidate target genes regulated by ZmEREB93 TF. The result of Y1H showed that ZmEREB93 directly bind to Zm00001d013611 promoter. 【Conclusion】 Maize ZmEREB93 TF specifically expressed in seeds and negatively regulated seed size.

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