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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
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    【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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    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
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    【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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    Function of Maize ZCN7 in Regulating Drought Resistance at Flowering Stage
    LI Yan, TAO KeYu, HU Yue, LI YongXiang, ZHANG DengFeng, LI ChunHui, HE GuanHua, SONG YanChun, SHI YunSu, LI Yu, WANG TianYu, ZOU HuaWen, LIU XuYang
    Scientia Agricultura Sinica    2023, 56 (16): 3051-3061.   DOI: 10.3864/j.issn.0578-1752.2023.16.001
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    【Objective】The main producing areas of maize is mostly located on the arid or semi-arid region that relying on the rainfed farming in China. The maize production losses caused by drought is a great threaten to food security. As a cross-pollinating crop, maize is mostly sensitive to water stress during flowering time. Drought at flowering stage will lead to asynchronous development between the male and female flower and cause massive grain yield loss. Thus, mining drought resistance related genes at flowering stage is important for maize drought resistance improvement and breeding. 【Method】In the present study, the phylogenic tree of 24 ZCN genes in maize genome, which is homologs of Arabidopsis FT gene, was build. The gene expression patterns of ZCN7 were analysis using qRT-PCR and in vivo GFP fluorescence imaging. A maize natural population consisting of 118 diverse inbred lines were planted in three environments, Beijing in 2021 and 2022 and Urumqi in 2022, to identify the flowering time related traits under different water treatments. The genomic variants around ZCN7 were detected by PCR and Sanger sequencing. The candidate gene association analysis was performed based on mixed linear model and the significant associated variants with drought induced anthesis-silking interval was obtained. The gene expression level of ZCN7 in natural population at flowering time was also measured by qRT-PCR. The differences of drought resistance traits and ZCN7 expression were compared between different haplotypes of significant associated variant. The Ubi1:ZCN7 overexpression transgenic maize were obtained, and the phenotypic performance was identified under different water treatments. 【Result】The 24 ZCN genes in maize genome included 15 FT like genes, 6 TFL1 like genes and 3 MFT like genes. The protein sequence of ZCN genes varied from 111 nn to 193 nn. The ZCN7 showed close relationship with ZCN8 and the protein sequence identity was 83.3% between the two genes. ZCN7 showed highest gene expression in the leaf blade at V12 stage. And the ZCN7-promoter:GFP vector was transformed to Arabidopsis and the GFP showed enriched signal at the blade edge of mature leaf. The candidate gene association analysis revealed a SNP variant at 1001 bp upstream of ZCN7 start codon had highest association signal with drought induced anthesis-silking interval under drought. The A/A and G/G haplotypes of SNP-1001 included 78 and 27 inbred lines, respectively. The anthesis-silking interval of A/A haplotype lines were significantly lower than G/G lines. And the ZCN7 gene expression of A/A haplotype lines were significantly higher than G/G lines. In addition, the ZCN7 overexpression transgenic lines showed significantly decreased anthesis-silking interval than wild type lines. Under drought, the anthesis-silking intervals of OE1 and OE2 were 2.3 and 2.6 days shorter than wild type lines. And the grain yield per plant and kernel number per plant of transgenic lines were significantly higher than wild type lines under drought, while the hundred kernel weight, kernel length and kernel width showed no significant difference. 【Conclusion】The maize ZCN7 played positive role in drought resistance and its overexpression improved grain yield by reducing anthesis-silking interval under drought.

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    Physiological Changes and Integrity of ATP Synthase Subunits mRNA in Naturally Aged Cotton Seeds
    SONG Ci, GU FengXu, XING ZhenZhen, ZHANG JunMing, HE WenXue, WANG TianBo, WANG YuLu, CHEN JunYing
    Scientia Agricultura Sinica    2023, 56 (10): 1827-1837.   DOI: 10.3864/j.issn.0578-1752.2023.10.001
    Abstract397)   HTML107)    PDF (769KB)(270)       Save

    【Objective】Seed aging is a complex biological process, previous studies have been used to elucidate the events. However, the mechanism of seed aging is still unclear. The naturally aged cotton seeds were used as experimental materials, and the physiological and biochemical changes as well as the changes in ATP synthase mRNA integrity that occurred in cotton seed during storage were investigated in order to provide a foundation for further illuminating the aging mechanism of cotton seeds.【Method】In this study, a collection of seeds (cultivar Xinluzao 74) that had been stored for 3 and 5 years served as the experimental materials, the newly harvested seeds were used as the control (CK). The germination percentage, water absorption and viability of cotton seeds were valued by germination test between paper, low constant temperature over method, and TTC staining method, respectively; The acid value and respiratory rate of cotton seeds were determined by the acid-base titration method, and the ATP synthase activity was detected with plant ATP synthase ELISA Kit. The mRNA integrity of ATP synthase subunit α, β, γ, ε, and δ in cotton embryo was analyzed by reverse transcription blocking-double primer amplification method.【Result】Our data suggest that seed vigor dramatically decreased over storage time. After 3 and 5 years of storage, the germination percentage of cotton seeds was significantly decreased from 98.7% to 84.0% and 58.0%, respectively (P<0.05). At the initial stage of seed imbibition (the first 4 h), the water absorption rate of seeds was significantly decreased by 11.0% and 26.9%, respectively. The results of TTC staining showed that only the radicle was slightly stained in seeds preserved 5 years but not the cotyledons and other organs stained; The acid value of seeds was significantly increased by 28.4% and 40.0%, respectively (P<0.05), this indicated that severe hydrolysis of lipid occurred in seeds. Seed respiration rate and ATP synthase activity showed an increasing trend during imbibition, but the increasement was significantly decreased (P<0.05); The respiration rate of seeds was reduced by 33.3% and 49.2% after 24 hours of imbibition, and the activity of ATP synthase was decreased by 17.9% and 73.4% after 12 hours of imbibition, respectively. The results of reverse transcription blocking-double primer amplification showed that the R value of ATP synthase subunits α, β, γ, and δ mRNAs stored in seeds were significantly decreased, but the subunit ε mRNA was significantly increased. These results indicated that the integrity of the ATP synthase subunits mRNA decreased to varying degrees during the natural storage process.【Conclusion】These results showed that a prolonged storage time could reduce seed vigor; The integrity loss of ATP synthase subunit mRNAs stored in seed embryos would cause ATP synthase subunit to be impaired and ATP synthase activity declined, thus lead to a decreased production of ATP and affect seed germination capacity. This might be one of the important reasons for cotton seed aging.

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    Research Progress on the Application of Non-Saccharomyces During Wine Fermentation
    WANG ChunXiao, YU JunZhu, ZHOU WenYa, XU YinHu
    Scientia Agricultura Sinica    2023, 56 (3): 529-548.   DOI: 10.3864/j.issn.0578-1752.2023.03.011
    Abstract357)   HTML66)    PDF (1835KB)(223)       Save

    Non-Saccharomyces yeast are naturally present on grape skin, which mainly play their roles in the maceration and initial stage of fermentation during winemaking process. More and more concerns have been recently focused on the application of non-Saccharomyces yeast in wine fermentation. Non-Saccharomyces yeast often have weaker fermentation ability than Saccharomyces cerevisiae and can convert the reducing sugar into ethanol and other fermentation by-products. Therefore, non-Saccharomyces are the potential excellent yeast for producing wine with complex flavor traits and lower ethanol degree. Different non-Saccharomyces yeast species have different metabolic characteristics in wine fermentation applications. The selection of non-Saccharomyces yeasts with certain characteristics for application in fermentation can improve the specialized quality of wine. This review was based on the initial summary on the species, winemaking traits, and application ways of commercial non-Saccharomyces yeast, and emphasized on the positive role of non-Saccharomyces in wine color, aroma, taste, safety and health, their metabolic mechanisms and corresponding research hotspot. The positive role of non-Saccharomyces in wine color included the promotion of high acid production, high polysaccharide production, high extracellular pyruvate production and low sorption properties. Different non-Saccharomyces yeast could promote the fruity aroma enhancement in wine by low production of ethanol, acetaldehyde, and volatile phenols, and high production of ethyl acetate, acetic acid ester, ethyl ester, higher alcohols, and enzymes related with the release of terpene and mercaptan, and therefore improve the aroma complexity of wine. Non-Saccharomyces yeast could regulate wine mouthfeel traits by high production of glycerol, polysaccharide, and lactic acid, and degradation of malic acid. In addition, non-Saccharomyces yeast could improve the safety quality of wine by decreasing the SO2 dosage as biological control agent, and reducing the content of toxic compounds through metabolic degradation during alcoholic fermentation. This review further analyzed the current research status on genome and microsatellite loci analysis. The main inoculation strategies were discussed on application of non-Saccharomyces yeast during wine fermentation, and six aspects were posed for further research concern. This review provided theoretical references for the research on application of the non-Saccharomyces yeasts in wine alcoholic fermentation.

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    Comprehensive Evaluation and Breeding Evolution of Early Maturing Upland Cotton Varieties in the Northwest Inland of China
    WANG CaiXiang,YUAN WenMin,LIU JuanJuan,XIE XiaoYu,MA Qi,JU JiSheng,CHEN Da,WANG Ning,FENG KeYun,SU JunJi
    Scientia Agricultura Sinica    2023, 56 (1): 1-16.   DOI: 10.3864/j.issn.0578-1752.2023.01.001
    Abstract356)   HTML70)    PDF (3232KB)(233)       Save

    【Objective】This paper evaluated comprehensively early maturity upland cotton varieties in northwest inland cotton-growing region of China, and uncovered the evolution rules of the main traits from the breeding cultivars in the region. It provides a useful reference for recommendation and breeding of main cotton varieties in northwest inland region. 【Method】A total of 110 early-maturing upland cotton varieties which were approved in northwest inland cotton-growing region from 1988 to 2021 were applied, and phenotypic identification of 12 main traits related to early maturity, yield, fiber quality and plant architecture was carried out in Dunhuang, Gansu province and Shihezi, Xinjiang Production and Construction Corps in 2020 and 2021, respectively. Clustering analysis, correlation analysis and principal component analysis were respectively used to evaluate the phenotypic characteristics of the cultivars, and carry out the breeding evolution analysis of their main traits. 【Result】The phenotype value of 12 main traits had large distribution range from 110 early-maturing upland cotton varieties in northwest inland cotton-growing region of China. The variation coefficient in descending order is: fruit branch length (FBL), boll number per plant (BN), boll opening rate (BOR), boll weight (BW), fiber micronaire (FM), fiber strength (FS), lint percentage (LP), fiber length (FL), flowering time (FT), fruit branch angle (FBA), fiber elongation (FE), and fiber uniformity (FU). By cluster analysis, these cultivars were divided into four groups: Ⅰ, Ⅱ, Ⅲ and Ⅳ, which were the population of high fiber quality, early maturity, loose plant type and high yield, respectively. Correlation analysis showed that early maturity was negatively correlated with yield and fiber quality related to traits, while the yield related to traits were positively correlated with the fiber quality traits, and most of them reached significant or extremely significant level. The 12 main traits were simplified into four principal components which had cumulative contribution rate of 66.92%. Based on the comprehensive evaluation results of these varieties by principal components, an excellent cultivar Zhongmian 113 ranked the first in the 110 early-maturing upland cotton varieties with a score of 0.67, which was characterized by early maturity, high yield and excellent fiber quality, and relatively loose plant type. Additionally, it was found that the early maturity character of cotton varieties approved in Gansu province was significantly better than that of varieties approved in northwest inland region and Xinjiang province, and the traits related to yield and fiber quality of cotton varieties approved in Gansu province were significantly lower than those of varieties approved in northwest inland region and Xinjiang province. During the breeding evolution of early maturing upland cotton varieties in northwest of China for more than 30 years, most of the traits related to yield and fiber quality showed significant upward trends, and the plant type was becoming more compact. BN was negatively correlated with BW, LP, FL and FS in early cultivars, while BN was positively correlated with BW, LP, FL and FS in recent cultivars. 【Conclusion】In the process of breeding and improvement of early maturing upland cotton varieties in northwest of China, the main traits related to yield and fiber quality had wide distribution, and they had significant improvement trends year by year. In the recently developed varieties, BN, FL and FS had been improved cooperatively.

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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
    Abstract350)   HTML95)    PDF (5241KB)(187)       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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    Influence of Plastic Film on Agricultural Production and Its Pollution Control
    ZHANG JinRui,REN SiYang,DAI JiZhao,DING Fan,XIAO MouLiang,LIU XueJun,YAN ChangRong,GE TiDa,WANG JingKuan,LIU Qin,WANG Kai,ZHANG FuSuo
    Scientia Agricultura Sinica    2022, 55 (20): 3983-3996.   DOI: 10.3864/j.issn.0578-1752.2022.20.010
    Abstract348)   HTML50)    PDF (553KB)(210)       Save

    Plastic film has been widely used in the farmland all over the world especially in arid and semi-arid areas because of its remarkable agricultural benefits, such as increasing soil temperature and moisture, reducing weed and pest damage, extending crop-growing areas, and consequently improving crop yield and quality. However, the degradation rate of plastic film is extremely slow, and the recovery of plastic film is also relatively backward in China, which lead to a large number of plastic debris in the farmland, causing plastic residues and microplastics pollution in the soil environment. Based on literature, investigation and statistical data, this research reviewed and prospects the impact of plastic film on agricultural production and pollution control in China. Plastic residues and microplastics have been reported to change the physical and chemical properties of soil, restrict soil water and nutrient transport, do harm to the growth, development and reproduction of soil animals and plants, change the abundance and community structure of soil microorganisms, and damage the soil health. In the long-term, plastic residues and microplastics pollution will cause a decline in crop yield and quality. Microplastics had the potential to be absorbed by plants, enter the human body through the food chain and pose a threat to human health. In addition, the large specific surface area of microplastics enabled them to become carriers of other pollutants (e.g. heavy metals, pesticides and antibiotics), causing combined pollution to the soil ecological environment. The standard of plastic film production and use in China was gradually being improved, however, there was still a certain gap compared with developed countries and regions. In addition, a sustainable recycling system of plastic film and the policy of preventing plastic residue and microplastics pollution have not been well formed in China, and the study of microplastics pollution in Chinese farmland soil was still very limited. Therefore, it is critical to solve the problem of plastic residues and microplastics pollution in the soil by evaluating the present situation of plastic residues and microplastics pollution in soils, quantifying the effects of microplastics on the soil environment, and evaluating risks of microplastics to the soil ecosystems, as well as exploring the measures of controlling soil plastic residues and microplastics pollution, and formulating relevant policies and regulations of preventing these pollution.

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    The Genetic Basis of Flavonoid Contents in Wheat and Its Application in Functional Wheat Variety Breeding
    CHEN Jie, CHEN Wei
    Scientia Agricultura Sinica    2023, 56 (13): 2431-2442.   DOI: 10.3864/j.issn.0578-1752.2023.13.001
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    Accompanying the elevated expenses on consumption, people’s urge upon food has been gradually changed from “eat to be fed” to “eat to be satisfied” and further to “eat to gain nutrition” and “eat to be healthy”. Accordingly, breeders considered the wheat breeding goals should be set as breeding wheat with better quality along with higher yield, wherein the phrase “functional wheat variety” was recently raised. Flavonoids comprise one of the most widely reported categories of metabolites, the contents of which have been included within the “functional wheat variety” breeding program for its connection with plant phenotypes and its contribution to human health. The combination of metabolomics approach and genetics design has been proved to be efficient in identifying the candidates that responsible for metabolite contents, that said its application in wheat was lagged behind due to the lately released wheat reference genome. Further, the deficient knowledge upon the genetic basis of metabolites has in turn constrained the application of breeding “functional wheat variety”. In the current manuscript, the research progresses on genetic basis of flavonoids are briefly summarized, and its application for wheat breeding is highlighted. Meanwhile, the metabolomics-assisted breeding frame is concepted. Ultimately, the “functional wheat variety” breeding program will be achieved through the combination of the fundamental researches and breeding applications.

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    Environmental Safety Risks in Agricultural Application of Effluents from Sugar Molasses-Based Fermentation Industries
    WANG XiaoBin, YAN Xiang, LI XiuYing, TU Cheng, SUN ZhaoKai
    Scientia Agricultura Sinica    2023, 56 (3): 490-507.   DOI: 10.3864/j.issn.0578-1752.2023.03.008
    Abstract339)   HTML29)    PDF (714KB)(96)       Save

    Sugar molasses is a by-product from sugar industries. The sugar molasses-based fermentation industries mainly refer to the fermentation industries using molasses from sugar mills as raw materials for alcohol or yeast fermentation. A large volume of effluents can be produced in the process of sugar molasses-based alcohol or yeast fermentation. Considering the possibility of resource utilization with such effluents, many sugar-producing countries (such as Brazil, India, and China) use the effluents for crop irrigation and fertilization or soil remediation directly into the farmlands by waste disposal methods. Because the effluents from sugar molasses-based fermentation industries are both high concentration organic wastewater, and heavy metal-polluted wastewater, which are difficult to be treated. With the long-term disposal of such effluents into the farmlands in some sugar-producing countries, the problems about ecological environment pollution in soil-crop-water systems are increasingly exposed. At present, some fertilizer production enterprises in China use such effluents as raw materials to produce organic water-soluble fertilizers (accounting for 32%), but the long-term research and monitoring data about environmental safety risks for agricultural application of the effluents from sugar molasses-based fermentation industries are still lack. This paper collected the relevant scientific research literatures since 1980 on the pollution characteristics of the effluents from sugar molasses-based fermentation industries, and their environmental impacts on agricultural application. Through the investigation and review on the relevant research data, this paper evaluated the environmental safety risks for agricultural application of the effluents from sugar molasses-based fermentation industries: (1) Such effluents were at a risk of seriously exceeding the limits for water quality standards, and a risk of ecotoxicity to plants. For example, such effluents had strong acidity, and high salinity, and contained not only high load organic pollutants, but also several heavy metals including 5 heavy metals (As, Hg, Cd, Pb and Cr), as well as other pollutants (such as Mn, Cu, Zn, Ni and Se, etc.). The concentrations of these pollutants mostly exceeded the limits of the Standards for Irrigation Water Quality (GB 5084—2021). (2) Such effluents for agricultural application were at a risk of farmland pollution. The concentrations of pollutants (such as Cu, Cd, Cr, Zn, Ni, Mn, Pb and Cl) detected from the soil samples irrigated with such effluents were about 10-641 times higher than those in the control soil. (3) Such effluents for agricultural application were at a safety risk of agricultural products. The concentrations of pollutants (such as Cu, Cd, Cr, Zn, Ni, Mn and Pb) detected in the grains of crops (wheat and mustard) irrigated with such effluents were about 3-12 times higher than those in the control crops, in which all the pollutants detected in the crops irrigated with such effluents exceeded both the allowable limits specified by FAO/WHO, but also the Maximum Levels of Contaminants in Food (GB 2762—2017) specified by China. In view of the issue of environmental safety risks for agricultural application of such effluents, therefore, it is necessary to strengthen the quality detection and risk control on the organic water-soluble fertilizer products with such effluents as raw material, to enable the safety of effluent utilization in agriculture.

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    Identification of Adult Plant Stripe Rust Resistance Candidate Genes of YrZ501-2BL by Gene Association and Transciptome Analysis in Wheat (Triticum aestivum L.)
    ZHANG Xu, HAN JinYu, LI ChenChen, ZHANG DanDan, WU QiMeng, LIU ShengJie, JIAO HanXuan, HUANG Shuo, LI ChunLian, WANG ChangFa, ZENG QingDong, KANG ZhenSheng, HAN DeJun, WU JianHui
    Scientia Agricultura Sinica    2023, 56 (8): 1429-1443.   DOI: 10.3864/j.issn.0578-1752.2023.08.001
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    【Objective】Stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), significantly reduced wheat production worldwide. Identification of stripe rust resistance genes is the foundation of improving wheat resistance breeding and revealing its genetic mechanism.【Method】A multi-omics approach combined with genome-wide association study (GWAS) was used for dissecting adult plant stripe rust resistance for wheat advanced breeding lines collected from International Maize and Wheat Improvement Center (CIMMYT) and International Centre for Agricultural Research in the Dry Areas (ICARDA) bread-wheat breeding programs. In the present study, a diversity panel of 411 wheat lines from CIMMYT and ICARDA was used for genome-wide association study and a major locus on chromosome arm 2BL was identified. In order to verify the stability of the locus, the resistant line Z501 with the resistance allele of the locus was crossed by the susceptible line Jinmai 79, and the locus tentatively named YrZ501 was successfully confirmed using linkage mapping based on F2:3 genetic population of Jinmai 79×Z501. Then we performed candidate gene analysis based on gene annotation, comparative genome, transcriptome and gene-based association analysis. 【Result】Combining GWAS and linkage mapping results, the YrZ501-2BL was located in the physical interval of 0.26 Mb (575.706-576.587 Mb) on chromosome 2B. According to the annotation information of Chinese Spring reference genome IWGSC v1.1, there were six high confidence genes of 12 genes in this region. Using online website, the target interval in the Chinese spring reference genome was compared with other published different ploidy wheat genomes. The six high-confidence genes within this interval can basically be found homologous in other wheat lines, and the genes arranged in the same order, indicating that the interval may not have large fragment insertions, deletions and inversions. The above results showed that we can perform candidate gene prediction analysis based on the reference genome information. After analysis of their transcriptomic data between the resistant parent Z501 and susceptible parent Jimai 79, only three genes, TraesCS2B02G406400, TraesCS2B02G406500 and TraesCS2B02G406600 showed variable expression levels and were induced by stripe rust infection. Further, they encode GATA transcription factor, SH3 domain-containing protein 2 and zinc finger protein, respectively. Gene-based association analysis revealed that there was a significant SNP (G1369A) in TraesCS2B02G406500 that was associated with stripe rust responses. Although this SNP (G1369A) did not cause amino acid coding changes (both TCG and TCA encode serine), it may be associated with alternative splicing. Moreover, it showed significant differences of the stripe rust responses between the different haplotypes (G1369A). Further analysis revealed two other variants G1377A and G1431A, that caused amino acid changes, i. e. valine (GTT) to isoleucine (ATT) and valine (GTG) to methionine (ATG), respectively. However, the two SNPs were rare variants as they accounting for only 0.87% of the 455 re-sequencing wheat accessions and they were not tested for significance. In summary, TraesCS2B02G406500 was preliminarily considered as an important candidate gene of YrZ501-2BL. In addition, the corresponding AQP markers were developed based on the SNPs among the YrZ501 candidate regions, which can be used to marker-assisted selection in molecular breeding application of wheat stripe rust resistance.【Conclusion】A candidate causal gene TraesCS2B02G406500 associated with stripe rust resistance was successfully identified on wheat chromosome 2B using an integrated method of multi-omics and association analysis, which laid a solid foundation for further gene cloning and functional verification.

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    Panicle Development and High-Yield Breeding in Rice
    LI YunFeng, REN DeYong
    Scientia Agricultura Sinica    2023, 56 (7): 1215-1217.   DOI: 10.3864/j.issn.0578-1752.2023.07.001
    Abstract336)   HTML84)    PDF (270KB)(280)       Save
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    Breeding and Application of a New Thermo-Tolerance Rice Germplasm R203
    LIU Gang, XIA KuaiFei, WU Yan, ZHANG MingYong, ZHANG ZaiJun, YANG JinSong, QIU DongFeng
    Scientia Agricultura Sinica    2023, 56 (3): 405-415.   DOI: 10.3864/j.issn.0578-1752.2023.03.001
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    【Objective】 The global warming has led to the increasingly serious heat damage on the heading and flowering stage of rice. To reduce the impact of heat damage on rice production and to ensure food security in China and even the world, new rice germplasms with thermo-tolerance on heading stage should be identified and new thermo-tolerance varieties need be bred. 【Method】Guanghui 128 (Qiguizao/Ce64//Minghui 63) was used as the heat resistant parent, through hybridization, multiple crossing and pedigree selection, the lines with high seed setting rate and small variation on heading and flowering stage during the high temperature were screened out for several generations’ breeding process. Then the selected higher generation lines were identified to create new thermos-tolerance rice germplasms in artificial climate chamber (The treated plants will be moved into the chamber on the flowering day, high temperature treatment is 9:00-15:00, 38℃, 15:01-8:59 28℃, the relative humidity is 75%, and the treatment lasts for 7 days), with analysis of agronomic trait. 【Result】The new germplasm R203 has stronger thermo-tolerance and higher seed setting rates under both normal and high temperature conditions (94.5% at normal temperature, 81.9% at high temperature, and 86.7% at relative). Its agronomic traits, quality and comprehensive resistance all meet the production standards. Above all, R203 has the potential to breed new thermos-tolerance hybrid rice varieties. The seed setting rates of 7 hybrid combinations with R203 as the male parent and seven three-line male sterile lines as the female parent were between 83.4%-99.4% under natural high temperature conditions. Among them, Taiyou 203, a new three-line medium indica hybrid rice has good qualities, the seed setting rate was 87.9%, the comprehensive relative heat resistance coefficient was 1.11, and the heat resistance reached level 1. In the production test, the yield increased by 5.36% compared with the control, and the yield increase point accounted for 85.71%. It has good high and stable yield, and the rice quality reached the second level of the ministerial standard. Thus Taiyou 203 has good promotion and application value. 【Conclusion】Currently, basic research on heat resistance is not enough to support the breeding of new practical heat resistant varieties, the rice resources in areas prone to high temperature and humidity are preferred as materials for breeding new heat tolerance lines, a new heat-resistant rice variety R203 was created by phenotypic selection, and a practical heat-resistant rice variety Taiyou 203 was developed by using heterosis.

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    Molecular Marker Assisted Identification and Application of Maize Germplasms for Maize Rough Dwarf Disease Resistance
    WANG JiangHao, WANG LiWei, ZHANG DongMin, GUO Rui, ZHANG QuanGuo, LI XingHua, WEI JianFeng, SONG Wei, WANG BaoQiang, LI RongGai
    Scientia Agricultura Sinica    2023, 56 (10): 1838-1847.   DOI: 10.3864/j.issn.0578-1752.2023.10.002
    Abstract331)   HTML55)    PDF (2438KB)(229)       Save

    【Objective】Molecular markers tightly linked to three maize rough dwarf disease (MRDD) resistant loci were employed to identify resistant inbred lines, then the classification of heterotic groups and analysis of combining ability of these inbred lines were carried out, which proved a highly efficient way for maize MRDD resistance breeding.【Method】A recombinant inbred lines (RILs) population consisting of 263 F9 lines was developed through single seed descent method from a segregating F2 population by crossing a resistant inbred line K36 to a susceptible inbred line S221. The MRDD resistances of the RILs were identified in different growing environments. Meanwhile the RILs were genotyped by employing three pairs of molecular markers, 5FR, 6W53 and IDP25K which were closely linked to the three resistant loci, qMrdd2, Rmrdd6 and qMrdd8. The excellent lines with disease resistance and good agronomic traits were selected out after field evaluation. Totally 24 maize inbred lines including the elite lines were genotyped using Maize 56K SNP array, then the genetic distances between the selected lines and other elite inbred lines were calculated according to Roger's algorithm and cluster analysis was conducted to classify the heterotic groups. Meanwhile, hybrid combinations were generated and the combining abilities were tested to screen the combinations with strong disease resistance and heterosis.【Result】The inbred line K36 were homozygous resistant at the three loci, qMrdd2, Rmrdd6 and qMrdd8 while S221 were homozygous susceptible. All the 263 RILs were genotyped into 21 patterns in terms of genetic composition of the three resistant loci. The lowest DSI (0.281) appeared when all the three loci were homozygous resistant while the highest DSI (0.776) appeared when the three loci were homozygous susceptible, which were consistent with the resistant and susceptible parents (0.257, 0.623). The order of DSI from low to high value for one homozygous resistant locus was Rmrdd6 (0.396), qMrdd8 (0.478) and qMrdd2 (0.654) when the other two loci were homozygous susceptible, which showed that Rmrdd6 and qMrdd2 performed the strongest and the weakest resistance while qMrdd8 was in the middle. The variation range of genetic distance between JR2136 with the genotype of three homozygous resistant loci and other 23 inbred lines was 0.2234-0.2895, with an average value of 0.2612. The inbred line with the smallest genetic distance was C413, and the largest was Chang7-2. According to the results of cluster analysis, JR2136 was classified into Reid group, hybrid combinations with inbred lines H92 and H521 belonging to Huanggai group performed strong disease resistance and heterosis.【Conclusion】The resistance of K36 to MRDD was controlled by three loci, qMrdd2, Rmrdd6 and qMrdd8, and it had quantitative genetic characteristics and gene additive effect. Maize varieties with homozygous resistant genotypes demonstrated the strongest disease resistance. The developed molecular markers closely linked with the three resistant loci have proved valuable tools in disease-resistant breeding and screening of resistant germplasm resources. It is feasible to use molecular markers for assisted selection and gene aggregation to select highly heterotic combinations with strong disease resistance.

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    Provincial Agricultural Ecological Efficiency and Its Influencing Factors in China from the Perspective of Grey Water Footprint
    DENG YuanJian,CHAO Bo
    Scientia Agricultura Sinica    2022, 55 (24): 4879-4894.   DOI: 10.3864/j.issn.0578-1752.2022.24.008
    Abstract321)   HTML38)    PDF (617KB)(65)       Save

    【Objective】This paper evaluated Chinese provincial agricultural ecological efficiency from the perspective of gray water footprint, revealed the spatial distribution characteristics of agricultural ecological efficiency, analyzed the main factors affecting agricultural ecological efficiency, and put forward policy suggestions to improve Chinese provincial agricultural ecological efficiency. 【Method】Based on the provincial panel data of China from 2000 to 2019, this paper comprehensively evaluated the agricultural ecological efficiency of Chinese provinces with the super efficiency SBM model considering the unexpected output, and used the spatial Dobbin model to analyze the spatial differences and influencing factors of agricultural ecological efficiency. 【Result】(1) In general, the agricultural grey water footprint showed a downward trend, but in some provinces (cities and districts), it showed an upward trend. From the ranking of grey water footprint from low to high, it could be seen that the provinces (cities and districts) in the forefront (i.e. with less grey water footprint) had a high level of economic development or a relatively low proportion of agricultural output value; the provinces (cities and districts) in the rear row (i.e. with more grey water footprint) had low economic development level or high agricultural output value. (2) During the observation period, the agricultural ecological efficiency fluctuated greatly in some years in the stable trend, and the average difference among provinces (cities and districts) was obvious and the distribution was extremely unbalanced. (3) Economic development level, fiscal expenditure for supporting agriculture, technological progress, agricultural disaster rate, planting structure and other factors had different impacts on Chinese agricultural ecological efficiency. With the improvement of both economic development level and people's living quality, both agricultural operators and consumers paid more attention to the protection of agricultural ecological environment and the quality of agricultural products, which have improved the level of regional agricultural ecological efficiency to a certain extent. But the pollution caused by regional economic and social development might also have a negative impact on agricultural ecological efficiency. Most of the financial support for agriculture was used to subsidize production links, such as pesticides, chemical fertilizers, and agricultural machinery. Although the agricultural production conditions have been improved and the agricultural economic productivity and efficiency have been improved, the improvement of agricultural ecological efficiency was not significant. The development of technology was very important in the agricultural production process, and the proper use of it would improve the agricultural ecological efficiency. The estimated results of agricultural disaster rate failed to pass the significance test, which might be because the expansion of agricultural disaster area would lead to the decline of agricultural ecological efficiency, but the annual disaster situation was not regular. The coefficient of planting structure was negative, which had a negative impact on agricultural production efficiency. This might be due to the high proportion of grain crop planting area in the total planting area of crops, and the high consumption of nitrogen fertilizer. 【Conclusion】As the evolution trend and difference of agricultural gray water footprint in various provinces (cities and districts) in China were obvious, the overall level of agricultural ecological efficiency was not high, and various factors have different impacts on agricultural ecological efficiency, it was necessary to improve the governance mechanism of agricultural gray water footprint; optimize the agricultural industrial structure and establish a compensation mechanism for agricultural water resources protection based on gray water footprint; improve the ways and policies of financial support for agriculture, and guide business entities to actively improve agricultural ecological efficiency.

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    Quantitative Detection Technology of Porcine-Derived Materials in Meat by Real-time PCR
    ZHAI XiaoHu,LI LingXu,CHEN XiaoZhu,JIANG HuaiDe,HE WeiHua,YAO DaWei
    Scientia Agricultura Sinica    2023, 56 (1): 156-164.   DOI: 10.3864/j.issn.0578-1752.2023.01.012
    Abstract319)   HTML32)    PDF (1687KB)(76)       Save

    【Objective】The aim of this study was to develop a rapid and accurate quantitative method for identifying porcine-derived materials. 【Method】Porcine microsatellites DNA were selected from GenBank nucleotide database. Primers specific for porcine were designed based on the sequences of microsatellite DNA. Genomic DNA from 10 kinds of common animals was amplified by PCR method. The specificity of selected microsatellite DNA to porcine-derived materials was judged by the amplification products. According to the microsatellite sequence, the specific primers and probes were designed to establish a Real-time PCR method for identifying porcine-derived materials. The double standard curve was used to quantify the porcine-derived materials and total animal-derived materials, respectively, and the percentage content of porcine-derived materials was calculated. 【Result】Porcine specific microsatellite DNA with the accession number EF172428 was selected. Only porcine DNA gave a fragment through PCR assay, while there was no amplification for other non-target animal species DNA. The limit of detection was 0.02 ng in a 25 μL reactive system using the Real-time PCR method. This method could accurately detect porcine-derived components in mixed DNA samples and mixed meat samples with 1.32% percent error and 1.06%-7.12% percent error, respectively. 【Conclusion】The quantitative detection method of porcine-derived materials by Real-time PCR in this research could be used to detect the percentage content of porcine-derived materials in mixed samples.

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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
    Abstract314)   HTML65)    PDF (2482KB)(194)       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
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    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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    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
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    【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 Reducing Nitrogen Application Rate on the Yields of Three Major Cereals in China
    DU WenTing,LEI XiaoXiao,LU HuiYu,WANG YunFeng,XU JiaXing,LUO CaiXia,ZHANG ShuLan
    Scientia Agricultura Sinica    2022, 55 (24): 4863-4878.   DOI: 10.3864/j.issn.0578-1752.2022.24.007
    Abstract310)   HTML36)    PDF (624KB)(215)       Save

    【Objective】 The present study investigated the effects of reducing nitrogen application rate on the yields of three major cereals in China and its relationship with soil and other factors, so as to clarify the feasibility of reducing nitrogen application. 【Method】 90 published papers from 2010 to 2021 were collected and analyzed the effects of different nitrogen fertilizer reduction ratios on yield, and its relationship with planting systems and different conditions (fertilizer type, soil organic matter content, total nitrogen, soil pH, and water management). 【Result】 Compared with conventional fertilization rate, 0-40% nitrogen reduction did not significantly reduce the yield of rice, 0-30% nitrogen reduction did not significantly affect the yields of wheat and maize, when the nitrogen reduction was 30%-40%, the yield of wheat and maize significantly reduced by 6.1% and 5.4%, respectively. The yield level without nitrogen input area did not significantly affect crop yield of the three cereals following reduction of nitrogen rate. When soil total nitrogen was more than 2 g·kg-1, rice yield with reduced nitrogen application (6.5 t·hm-2) was significantly higher than that with conventional nitrogen application (6.3 t·hm-2); when total nitrogen was more than 1 g·kg-1, wheat yield with reduced nitrogen application (6.9 t·hm-2) was significantly lower than that with conventional nitrogen application (7.4 t·hm-2); when total nitrogen was more than 1.5 g·kg-1, maize yield with reduced nitrogen application (8.8 t·hm-2) was significantly lower than that with conventional nitrogen application (9.1 t·hm-2). When soil organic matter content was more than 30 g·kg-1, rice yield with reduced nitrogen application (6.9 t·hm-2) was significantly higher than that with conventional nitrogen application (6.7 t·hm-2), but soil organic matter content were 10-20 g·kg-1 and more than 20 g·kg-1, the reducing nitrogen application significantly reduced wheat yield. When soil pH was lower than 6.5, rice yield with reduced nitrogen application (6.6 t·hm-2) was significantly higher than that with conventional nitrogen application (6.4 t·hm-2). Wheat yield (6.6 t·hm-2) with reducing nitrogen application under single cropping was significantly higher than that with conventional nitrogen application (5.9 t·hm-2); maize yield (8.9 t·hm-2) with reducing nitrogen application under double cropping was significantly lower than that with conventional nitrogen application (9.1 t·hm-2). Based on common fertilizer, wheat yield with reducing nitrogen application (6.8 t·hm-2) was significantly lower than that with conventional nitrogen application (7.1 t·hm-2). Under rainfed, wheat yield with reducing nitrogen application (5.9 t·hm-2) was significantly lower than that with conventional nitrogen application (6.6 t·hm-2). 【Conclusion】 The yield of three major cereals in China can be maintained by reducing conventional nitrogen application rate by 30% although crop yield varied to certain extent with soil properties and management measures. Therefore, the reduced application of nitrogen fertilizer needed to be adjusted according to soil properties and management practices to achieve high yield and high nitrogen efficiency.

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    Spatial-Temporal Variation of Cultivated Land Soil Basic Productivity for Main Food Crops in China
    LI YuHao,WANG HongYe,CUI ZhenLing,YING Hao,QU XiaoLin,ZHANG JunDa,WANG XinYu
    Scientia Agricultura Sinica    2022, 55 (20): 3960-3969.   DOI: 10.3864/j.issn.0578-1752.2022.20.008
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    【Objective】 Soil basic productivity is the cornerstone of realizing high and stable yield for food crops. The temporal change trends and spatial variation characteristics of cultivated land productivity for main food crops were defined, so as to provide the important theoretical support for ensuring food security and improve cultivated land quality in China. 【Method】 In this study, based on the national long-term positioning monitoring network of cultivated land quality from 1988 to 2019, the long-term monitoring data of the check area were selected with non-fertilization treatment and the conventional area with farmers' fertilization treatment in the first 3-5 years since the establishment of each monitoring point. The temporal and spatial changes in yield of maize, rice and wheat and soil productivity contribution rates were analyzed in China. 【Result】 In the past 30 years, the grain crops’ yield and soil productivity contribution rates showed an overall increasing trend with time, and the annual growth rate of crop yield showed the change law of non-fertilizer area < conventional area, rice < wheat < maize. The yield of maize, wheat and rice in the non-fertilizer area increased from 2 370, 1 712 and 3 111 kg·hm-2 in 1988 to 4 852, 3 258 and 4 167 kg·hm-2 in 2019, respectively, and increased by 104.7%, 90.2% and 34.0%, respectively. The yield of maize, wheat and rice in the conventional area increased from 5 356, 3 296 and 5 970 kg·hm-2 in 1988 to 8 859, 6 515 and 7 825 kg·hm-2 in 2019, respectively, with the increment of 65.4%, 97.6% and 31.0%, respectively. The contribution rate of soil productivity for the three major food crops in China from 2015 to 2019 was 52.7%, which was significantly increased by 7.3% compared with 45.4% in 1988-1994. Among them, the contribution rate from maize was 54.3%, which was 12.2% higher than that of 42.1% in 1988-1994. The contribution rate from rice was 53.3%, which was 6.7% higher than that of 46.6% in 1988-1994. The soil productivity contribution rate from wheat increased with the year as a whole, and was lower than that in maize and rice as a whole. The spatial distribution of soil productivity contribution rate for the three major grain crops was quite different. The Northeast region and Yellow River and Huaihai region were higher, which were 56.5% and 54.1%, respectively, followed by the Southwest region and South region, which were 53.7% and 52.9%, respectively. Gan Xin region and Qinghai-Tibet region were the lowest, only 38.7% and 40.4%, respectively. The random forest model was used to rank the soil factors affecting the basic soil productivity contribution rate in the three major grain crop systems. Among them, soil available potassium, organic matter content and soil bulk density were the key factors affecting the spatial distribution of maize basic soil fertility contribution rate; soil available phosphorus, available potassium and organic matter content were the key factors affecting the spatial distribution of wheat basic soil fertility contribution rate; soil pH, soil available phosphorus and organic matter content were the key factors affecting the spatial distribution of rice basic soil fertility contribution rate.【Conclusion】 Over the past 30 years, the soil basic productivity for three major grain crops in China has been continuously improved, but there were great differences among regions and the overall level was still low, which was far lower than that of developed countries in Europe and United States. Soil available potassium content, soil available phosphorus content and soil pH are the most key factors affecting the spatial distribution of basic soil fertility contribution rate of maize, wheat and rice, respectively.

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    Meta-Analysis of Yield Effects and Influencing Factors of Cover Crops on Main Grain Crops in China
    MA JiaYu, WANG Tao, LIU XiaoLi, WANG Li, ZHANG XueCheng, WANG WenTao, KONG FanSheng, HUANG XueJun, WANG ZiYi, WANG YanDong, ZHEN WenChao
    Scientia Agricultura Sinica    2023, 56 (10): 1871-1880.   DOI: 10.3864/j.issn.0578-1752.2023.10.005
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    【Objective】The objective of this study was to clarify the effect of cover cropping on the yield of main grain crops in China, and to investigate the significant influencing factors, so as to provide a scientific basis for the promotion and application of cover crops in China.【Method】A Meta-analysis including data from 903 pairwise observations from 137 publications from 1980 to 2022 was conducted to elucidate the effect of “fallow” versus “cover cropping” on yield of main grain crops. Meta regression was also conducted to explore the factors influencing the effect of cover crops on grain crops yield.【Result】Under cover crops, grain crop yields increased significantly by 12.2% compared to fallow, with wheat, rice and maize yields increasing significantly by 9.5%, 11.9%, and 19.6%, respectively. In addition, grain crop yields increased by 9.5% and 12.4% for winter and summer cover crops, respectively. Among the different types of cover crops, leguminous cover crops increased grain crop yields by 12.9% (February orchid 14.2%, Chinese milk vetch 11.8%, vetch 9.5%, pea 7.8%, soybean 7.4%), while cruciferous and gramineous cover crops increased grain crop yields by 9.3% and 8.3% (rape 7.0%, ryegrass 7.9%), respectively. However, compared with pure stands, cover crop mixtures more markedly increased grain crop yield by 17.3%. Furthermore, cover cropping years and sunshine hours significantly increased the effect of cover crops. High precipitation and temperature increased the effect of cover crops at high latitudes, while high precipitation and temperature decreased the effect of cover crops at low latitudes.【Conclusion】During the fallow period, cover crops mixtures contribute to increase grain crops yields, reduce surface exposure and make full use of solar, thermal, water and soil resources, especially during the northern summer and southern winter.

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    Effects of Returning Green Manure to Field Combined with Reducing Nitrogen Application on the Dry Matter Accumulation, Distribution and Yield of Maize
    WANG PengFei, YU AiZhong, WANG YuLong, SU XiangXiang, LI Yue, LÜ HanQiang, CHAI Jian, YANG HongWei
    Scientia Agricultura Sinica    2023, 56 (7): 1283-1294.   DOI: 10.3864/j.issn.0578-1752.2023.07.007
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    【Objective】 In order to provide the theoretical basis for the development of high-yield and high-efficiency maize production technology in this area, the characteristics of dry matter accumulation and distribution and the response of grain yield to the return of green manure to the field combined with nitrogen reduction were analyzed in the oasis irrigation area. 【Method】 The field experiment was carried out in Hexi Oasis Irrigation Area, Gansu Province from 2020 to 2021. The combination of green manure returning to the field and different nitrogen reduction ratios (green manure combined with nitrogen reduction 0%, N100; green manure combined with nitrogen reduction 10%, N90; green manure combined with nitrogen reduction 20%, N80; green manure combined with nitrogen reduction 30%, N70; green manure combined with nitrogen reduction 40%, N60) on the distribution of dry matter accumulation in maize and impact on production. 【Result】 After the jointing stage, the aboveground dry matter accumulation under N80 and N90 treatments was significantly higher than that of N70 and N60 treatments. At the mature stage, the aboveground dry matter accumulation under N80 increased by 13.3%-23.2% compared with N70 and N60 treatments, and N90 was higher than N70 and N60 treatments. Compared with the N70 and N60 treatments, the maximum growth rate and average growth rate of the aboveground dry matter under N80 were significantly increased by 9.5%-21.2% and 13.0%-23.2%, respectively; N90 significantly increased by 10.2%-21.8% and 13.9%-23.7% compared with N70 and N60 treatments, both of which effectively delayed the decrease of aboveground dry matter accumulation rate of maize from silking stage to grain filling stage. Compared with N70 and N60, the maximum growth rate of dry matter under N80 treatment was 2.44 d and 2.77 d earlier than that under N70 and N60, respectively, and N90 was 1.92 d and 2.3 d earlier than the N70 and N60 treatments, respectively. N80 and N90 promoted the distribution of dry matter in the ears of maize, and effectively increased the contribution rate of dry matter transport before flowering to grain dry matter accumulation. At the same time, the post-flowering dry matter accumulation under N80 increased by 12.2% and 20.4% compared with N70 and N60 treatments, respectively. Compared with the N70 and N60 treatments, the post-flowering dry matter accumulation under N90 was increased by 12.4% and 20.5%, respectively, and the difference was significant. There was no significant difference in maize grain yield among N100, N90, and N80 treatments, but the maize grain yield under N80 increased by 16.8% and 27.4%, respectively. Compared with N70 and N60 treatments, the yield under N90 treatment increased by 17.4% and 27.9%, respectively, with significant differences. 【Conclusion】 The return of leguminous green manure to the field combined with 10% and 20% nitrogen reduction treatments increased the aboveground dry matter accumulation and accumulation rate of maize, promoted the distribution of dry matter in the ears at maturity, and improved the pre-flowering dry matter transport on grain dry matter. The cumulative contribution rate could be used as the recommended nitrogen application method for high maize yield in oasis irrigated areas.

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    Construction of A High-Density Genetic Map and QTL Mapping for Yield Related Traits in Upland Cotton
    JIA XiaoYun, WANG ShiJie, ZHU JiJie, ZHAO HongXia, LI Miao, WANG GuoYin
    Scientia Agricultura Sinica    2023, 56 (4): 587-598.   DOI: 10.3864/j.issn.0578-1752.2023.04.001
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    【Objective】By constructing a high-density SNP genetic map, QTL mapping for cotton yield related traits of multiple populations was carried out to obtain stable and accurate QTL. It will provide references for the excavation of yield trait regulatory genes and the development of effective molecular markers. 【Method】Jifeng 1271 with high and stable yield and Jifeng173 with super fiber quality were used to construct an F2 population composing of 200 plants. A high-density SNP genetic map was constructed by GBS (Genotyping by sequencing), and QTL mapping was carried out for lint percentage, seed index and boll weight of F2, F2:3 and F2:4 populations. Genes in major and stable QTL were annotated, and the expression patterns in different tissues were analyzed for candidate genes selection. 【Result】A total of 383.07 Gb data was obtained by GBS, including 26.93 Gb for the maternal cultivar Jifeng 1271, 27.30 Gb for the paternal inbred line Jifeng 173 and 328.84 Gb for the 200 F2 plants, and Q30 scores were 90.55%, 89.95% and 95.77%, respectively. And 1 305 642 SNP markers were developed in the F2 population, including 410 726 aa×bb type SNP that were used for genetic map construction. A high-density genetic map containing 16 088 SNP and spanning 4 282.81 cM was constructed, and the average genetic distance between adjacent SNP was 0.27 cM. Collinearity analysis proved high quality of the genetic map. A total of 108 yield related QTL were mapped, including 34 lint percentage QTL, 36 seed index QTL and 38 boll weight QTL. 30 QTL overlapped with or were close to the published QTL, and the other 78 QTL were new. 10 major QTL and 16 stable QTL were found, and 5 major QTL could be mapped in 2 or 3 populations. qLP-A13-4 could be mapped in 3 populations, and the R2 reached 13.78%. qLP-A13-6 could be mapped in 2 populations, and the R2 reached 10.01%. qLP-D10-2 could be mapped in 2 populations, and the R2 reached 10.92%. qSI-D10-1 could be mapped in 2 populations and the R2 reached 12.31%. qBW-D5-3 could be mapped in 2 populations and the R2 reached 15.54%. A total of 3 415 genes were annotated in these major and stable QTL. By KEGG and GO analysis, the annotated genes are mainly involved in plant hormone signal transduction, TCA cycle, biosynthesis of secondary metabolites and amino acids, carbon fixation in photosynthetic organisms. Using the transcriptome data of TM-1 and NDM8, 8 genes were highly expressed in fiber, ovule or seed, which may be important candidate genes for boll weight and yield by regulating lint percentage or seed index. 【Conclusion】An intra-specific high-density genetic map was constructed for upland cotton. 108 yield related QTL were mapped, 5 major QTL could be mapped in at least 2 populations, and 8 candidate genes with high expression level in fiber, ovule or seed were identified.

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    Identification of Excellent Wheat Germplasms and Classification of Source-Sink Types
    NAN Rui, YANG YuCun, SHI FangHui, ZHANG LiNing, MI TongXi, ZHANG LiQiang, LI ChunYan, SUN FengLi, XI YaJun, ZHANG Chao
    Scientia Agricultura Sinica    2023, 56 (6): 1019-1034.   DOI: 10.3864/j.issn.0578-1752.2023.06.001
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    【Objective】 The aim of this study is to screen the evaluation indexes of wheat source-sink and classify the source-sink types. In addition, the relationships between different source-sink types and the agronomic traits, yield and grain quality of wheat were also clarified, which provides a better understanding of wheat source-sink metabolism and wheat breeding. 【Method】 In this study, the related agronomic traits of source metabolism and sink metabolism of 190 wheat varieties which from different regions were measured. Then, the source-sink metabolic capacity of wheat was evaluated by principal component analysis, and the superior wheat materials were selected according to the composite score. Furthermore, the hierarchical clustering was conducted based on the source size (leaf area), source activity, sink number and sink activity. Then, based on the clustering results, the source-sink types of wheat were classified and the source-sink characteristics of different region of wheats were analyzed. Meanwhile, the agronomic, yield and quality traits of different wheat source-sink types were compared and analyzed. 【Result】 For better understanding the results, six indicators related to source activity were converted into three independent indicators (photochemical quenching coefficient, maximum photosynthetic potential, chlorophyll content), and five indicators related to sink activity were converted into two independent indicators (maximum filling rate, filling duration) based on the principal component analysis. The cumulative contributions of three source activity indicators and two sink activity indicators were 82.80% and 92.90%, respectively. Then the top 10 wheat varieties were screened based on the source activity, source size (leaf area), sink activity, and sink number (number of spike grains). According to the source-library relationship, all the wheat varieties were divided into three major categories and eight subcategories, including sufficient source-weak sink type (medium source-weak sink type, strong source-medium sink type), weak source-sufficient sink type (medium source-strong sink type, weak source-medium sink type) and source-sink balance type (weak source-weak sink type limited by sink activity, weak source-weak sink type limited by source activity and grain number per spike, medium source-medium sink type, and strong source-strong sink type). 76.84% of wheat lines were contained in three subcategories (weak source-weak sink type, the medium source-strong sink type, and strong source-strong sink type), other wheat lines were distributed in other subcategories evenly. Most wheat varieties of China showed similar source-sink relationship, which presented the medium level of source activity, leaf area and grain number per spike, while the sink activity was high. But the sink activity of wheat varieties which were cultivated at the middle and lower reaches of the Yangtze River is low. The plant height, length of uppermost internode and spikelet number in different categories indicated that the sufficient source-weak sink type>source-sink balance type>weak source-sufficient sink type, and the dry protein content, dry wet gluten content and sedimentation value in different categories showed that source-weak sink type > source-sink balance type > weak source-sufficient sink type. Grain water absorption showed that the stronger the sink activity had the higher the water absorption rate. The yield of per plant was different among different source-bank groups, but it was positively correlated with the source activity and the number of grains per spike in the three subcategories which contained most wheat varieties. 【Conclusion】 In this study, photochemical quenching coefficient, maximum photosynthetic potential and chlorophyll content could be used as the main indexes to evaluate the activity of wheat source. The maximum filling rate and filling duration could be used as the main indexes to evaluate the activity of wheat sink. In practical production, the wheat yield could be improved by increasing the number of grains per spike and the activity of source. When the supply capacity of source is stronger than the absorption capacity of sink, the plant height, peduncle length, spikelet number, dry protein content, dry wet gluten content and sedimentation value would be increased. Strong sink activity would help us to improve the water absorption of wheat grains.

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    Effects of Cultivation Patterns on Grain Yield, Nitrogen Uptake and Utilization, and Population Quality of Wheat Under Rice-Wheat Rotation
    DING JinFeng, XU DongYi, DING YongGang, ZHU Min, LI ChunYan, ZHU XinKai, GUO WenShan
    Scientia Agricultura Sinica    2023, 56 (4): 619-634.   DOI: 10.3864/j.issn.0578-1752.2023.04.003
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    【Objective】This study aimed to provide the theoretical and technical support for the synergic cultivation of good-quality, high-yield, and high-efficiency of wheat under the rice-wheat rotation. 【Method】 In 2017-2018 and 2018-2019, the cultivation patterns of tradition (TCP), high yield (HCP), reducing fertilizer (RFCP), and reducing fertilizer and increasing planting density (IDCP) were conducted in Suining (northern Jiangsu) and Hanjiang and Yangzhou (middle area of Jiangsu) to study the differences in grain protein content, grain yield, nitrogen efficiency, and economic benefits. The excepted results could clarify the patterns achieving high yield and high efficiency and the characteristics of their wheat population qualities and nitrogen absorption and transportation, explore the relationship between yield, nitrogen efficiency and agronomic physiological traits, and then reveal the approaches to realize high yield and high-efficiency synergy. 【Result】 The effects of cultivation patterns on wheat grain yield, net economic benefit, and nitrogen efficiency were different depending on the ecological conditions in the various years and sites. The wheat grain protein content under different cultivation patterns was more than 12.5%, but which under HCP and RFCP was 13%-14%. In 2018, IDCP achieved the highest grain yield and economic net benefit with 31.5%-33.5% and 104.4%-239.1% higher than TCP, respectively, followed by HCP and RFCP. In 2019, the grain yield under HCP was the highest, which was 8.1%-13.2% higher than that under TCP, followed by RFCP and IDCP. In addition, IDCP could obtain stable or increased net economic benefits compared with TCP because of less fertilizer inputs. The above results indicated that compared with other patterns, grain yield, nitrogen efficiency, and economic benefits under TCP were relatively lower. HCP could achieve more stable and higher grain yield as well as higher protein content, and IDCP achieved the highest yield potential, economic benefits, and nitrogen efficiency but had a low grain protein content. High yield was achieved by increasing single-spike yield based on enough spike number, and the high yielding HCP mainly increased grains per spike, but IDCP achieved high grain weight. HCP achieved high spike number mainly depended on tiller fertility, and IDCP depended on the synergistically increasing tiller number and tiller fertility. The suitable range of the ratio of tiller number at the beginning of wintering stage to spike number was 0.9-1.1 for high yield population. Further analysis showed that the high yield patterns could improve the leaf photosynthetic rate and maintain a high photosynthetic area after anthesis, indicating high-level coordination of the source-sink relationship and enlarged source level. The results also indicated that improving nitrogen absorption efficiency based on high nitrogen physiological efficiency was the key for realizing high nitrogen use efficiency. The nitrogen accumulation in the HCP population was low at the early growth stage, but the absorption capacity was gradually increased at the middle and late growth stage, finally promoting nitrogen transportation. The IDCP population also had strong nitrogen absorption capacity during the middle and early growth stage and also showed a sufficient transportation level. The relationships of grain yield and nitrogen use efficiency with agronomic and physiological traits under different ecological conditions and cultivation patterns were analyzed, and it was found that increasing tiller fertility of the crop population contributed to a higher photosynthetic area per stem and leaf photosynthetic rate at the grain-filling stage, which increased single-spike yield and wheat production. Besides, the high tiller fertility also promoted nitrogen absorption capacity before anthesis increasing nitrogen transportation and use efficiency. 【Conclusion】 In conclusion, the synergistic approach to achieve high yield and high efficiency of wheat under the rice-wheat rotation was to develop large spikes especially increase grain weight based on obtaining sufficient spikes and to establish the population with sufficient quantity and high quality. The latter included that the tiller number of the population before wintering stage met the expected spike number with improving tiller fertility, the nitrogen absorption and transportation level was high before the anthesis stage, and the photosynthetic area and intensity of single stem could maintain a high level after the anthesis to promote the grain filling. The present study also indicated that technologies realizing high-yield and high-efficiency production needed to emphasize moderately increasing planting density, limitedly reducing nitrogen application, increasing topdressing nitrogen with reducing base fertilization, and precisely applying fertilization.

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    Identification of Pathogenic Fusarium spp. Causing Maize Ear Rot and Susceptibility of Some Strains to Fungicides in Jilin Province
    CHAI HaiYan,JIA Jiao,BAI Xue,MENG LingMin,ZHANG Wei,JIN Rong,WU HongBin,SU QianFu
    Scientia Agricultura Sinica    2023, 56 (1): 64-78.   DOI: 10.3864/j.issn.0578-1752.2023.01.005
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    【Objective】The objective of this study is to clarify the population distribution of Fusarium spp. of maize ear rot in Jilin Province and the inhibitory effect of fungicides on the growth of Fusarium mycelium, and to provide a basis for the targeted control of maize ear rot. 【Method】149 samples of maize ear rot collected from 36 cities and counties in Jilin Province in 2020 were isolated and identified by tissue isolation and molecular biology methods. The specific toxin synthesis primers of related genes were synthesized using Fusarium graminearum species complex (FGSC) toxin. The toxigenic chemotypes were detected, and the pathogenicity of some FGSC was determined. The inhibitory effect of 7 fungicides on FGSC was determined by the mycelial growth rate method. 【Result】A total of 233 Fusarium strains were isolated, belonging to 4 Fusarium complex species, including 9 Fusarium species, which were F. verticillioides, F. boothii, F. graminearum, F. proliferatum, F. asiaticum, F. chlamydosporum, F. fujikuroi, F. equiseti and F. subglutinans. The isolation frequencies were 33.05%, 26.18%, 25.32%, 12.45%, 0.86%, 0.86%, 0.43%, 0.43% and 0.43%, respectively. The isolate frequency of FGSC was the highest, which was 52.36%, and it was the dominant pathogen of maize ear rot in Jilin Province. The proportions of F. boothii, F. graminearum and F. asiaticum in FGSC were 50.00%, 48.36% and 1.46%, respectively. The phylogenetic tree showed that the interspecific and intraspecific genetic diversity of FGSC was rich. The results of pathogenicity assay showed that 52.73% of FGSC were medium pathogenic strains. F. graminearum isolated from the main maize producing areas in the east had the strongest pathogenicity. Toxigenic chemotype detection showed that F. asiaticum produced nivalenol (NIV) chemotype, F. graminearum and F. boothii produced 15-acetyl-deoxynivalenol (15-AcDON) chemotype. The EC50 of the 7 fungicides for inhibiting the growth of FGSC ranged from 0.02 to 19.45 μg·mL-1. Fludioxonil (FS), imazalil (FS), flusilazole (EC), tebuconazole (TC) and myclobutanil (EW) had good inhibitory effects on FGSC and the difference was not significant. The EC50 of FGSC was less than 1.20 μg·mL-1 and EC90 was less than 100 μg·mL-1. The difference of EC50 between F. graminearum and F. boothii was significant under 30% pyraclostrobin treatment. The EC50 of F. graminearum was 10.24 times higher than that of F. boothii. 【Conclusion】The dominant pathogenic Fusarium of maize ear rot in different maize producing areas of Jilin Province is different. F. graminearum and F. boothii are dominant species in the east and west, and F. verticillioides is dominant species in the middle. The interspecific and intraspecific genetic diversity of FGSC is rich. Fludioxonil, imazalil, flusilazole, tebuconazole and myclobutanil have better antifungal effect on FGSC. There is no significant difference in the fungicides susceptibility among FGSC.

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    Discussions on Frontiers and Directions of Scientific and Technological Innovation in China’s Field Crop Cultivation
    ZHANG HongCheng, HU YaJie, DAI QiGen, XING ZhiPeng, WEI HaiYan, SUN ChengMing, GAO Hui, HU Qun
    Scientia Agricultura Sinica    2022, 55 (22): 4373-4382.   DOI: 10.3864/j.issn.0578-1752.2022.22.004
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    China’s total grain output has exceeded 650 million tons since seven years ago, with the great achievement of ever-increased grain output for 18 consecutive years. However, China’s cereal production is facing many severe challenges, such as the shortage of agricultural resources per capita, higher cost for crop production per hectare, sharp decrease of labor population and progressively increase of grain import. Therefore, it is necessary to discuss the frontiers and the directions of scientific and technological innovation in China’s field crop cultivation. According to the existing problems in field crop production, the major scientific and technological requirements of China’s field crop were elaborated, such as the cooperative cultivation of high-quality and high-yield and high-efficient, the green cultivation of carbon fixation and energy conservation and emission reduction, and the “unmanned” intelligent cultivation. The scientific and technological frontiers and development status and trends of field crop cultivation at home and abroad were analyzed emphatically. The key scientific and technological breakthrough directions and paths were pointed out in three aspects: The coordination cultivation of high-quality and high-yield and high-efficient, the green cultivation of carbon fixation and energy saving and emission reduction, and the “unmanned” intelligent cultivation. Finally, the measures and suggestions for scientific and technological innovation of China’s field crop cultivation were put forward from the aspects of policy top-level design and effective investment, increasing the research and development of basic theories, the key technologies and practical products, and increasing the cultivation of compound talents. In the future, it is necessary to significantly improve grain quality and planting efficiency under the premise of continuously increasing grain yield through the collaborative cultivation of high-quality, high-yield and high efficiency in field crop cultivation. Through the green cultivation of carbon fixation and energy conservation and emission reduction, less material input and high efficient utilization of resources can be achieved. Through integration and innovation of various aspects of agronomy and agricultural machinery intelligence, the “unmanned” intelligent cultivation can be constructed for greatly less labor input and higher efficiency of large-scale production. Finally, it is to realize Chinese style modernization of field crop production, to ensure grain security and effective supply of agricultural products.

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    Mapping and Analysis of QTL for Embryo Size-Related Traits in Tetraploid Wheat
    CHEN JiHao, ZHOU JieGuang, QU XiangRu, WANG SuRong, TANG HuaPing, JIANG Yun, TANG LiWei, $\boxed{\hbox{LAN XiuJin}}$, WEI YuMing, ZHOU JingZhong, MA Jian
    Scientia Agricultura Sinica    2023, 56 (2): 203-216.   DOI: 10.3864/j.issn.0578-1752.2023.02.001
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    【Objective】 This study is to excavate embryo-related quantitative trait loci (QTL) with potential breeding value, to explore the genetic relationship between embryo and other agronomic traits in tetraploid wheat, and finally to aim at laying an important foundation for the fine mapping and breeding utilization of embryo-related traits in the future. 【Method】A total of 121 F8 recombinant inbred lines (RIL) constructed by crossing tetraploid durum wheat (Ailanmai) and wild emmer wheat (LM001) were used. This RIL population was planted in five different environments including Chongzhou (2018-2020), Wenjiang (2020), and Ya'an (2020) in Sichuan Province for phenotypic evaluation of embryo length (EL), embryo width (EW), embryo length/embryo width (EL/EW), embryo length/kernel length (EL/KL), embryo width/kernel width (EW/KW), and embryo area (EA). QTL mapping was performed based on a genetic linkage map constructed based on the wheat 55K SNP. 【Result】 The embryo size-related traits showed approximately normal distribution in the RIL population satisfying the genetic characteristics of quantitative traits. A total of 27 QTL for embryo size-related traits were detected in five environments over three years. Among them, seven ones controlling EL could contribute 7.75%-21.74% of phenotypic variation. Seven QTLs controlling EW could explain 7.67%-33.29% of phenotypic variation. Five stable and major QTLs (QEL.sicau-AM-3B, QEW.sicau-AM-2B, QEW/KW.sicau-AM-2B, QEL/EW.sicau- AM-2B-1 and QEA.sicau-AM-2B) were identified, and they explained 11.88%-18.99%, 21.77%-29.41%, 8.80%-24.92%, 12.79%- 25.69% and 10.47%-15.22% of phenotypic variation, respectively. In addition, four QTL-rich regions were identified in the embryo size-related loci mentioned above. The QTL controlling EL/KL and EL was located on chromosome 1B, that for EW, EL/EW, EW/KW, and EA was located on 2B, that controlling EL and EA was on 3B, and that controlling EL/EW and EW/KW was on 6B. Embryo size was significantly and positively correlated with kernel size. Further, the major QTL for EL, QEL.sicau-AM-3B was co-located with that for kernel length identified previously, but that for EW QEW.sicau-AM-2B was independent of that for kernel width. Four genes likely involved in regulation of embryo size were identified in intervals where major QTL were mapped. 【Conclusion】Five stable and major QTLs were identified: QEL.sicau-AM-3B, QEW.sicau-AM-2B, QEW/KW.sicau-AM-2B, QEL/EW.sicau-AM-2B-1, QEA.sicau-AM-2B, among which QEW.sicau-AM-2B may be novel.

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    Genome-Wide Association Studies and Mining for Favorable Loci of Root Traits at Seedling Stage in Wheat
    WANG Mai, DONG QingFeng, GAO ShenAo, LIU DeZheng, LU Shan, QIAO PengFang, CHEN Liang, HU YinGang
    Scientia Agricultura Sinica    2023, 56 (5): 801-820.   DOI: 10.3864/j.issn.0578-1752.2023.05.001
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    【Objective】Plant roots are critical for water and nutrient acquisition, crop growth and development as well as yield formation. Exploring SNP loci significantly associated with root traits in wheat at seedling stage and mining candidate genes, will lay a foundation for understanding the genetic mechanism of wheat root system architecture and breeding wheat elite varieties with better root architecture.【Method】In this study, 189 diverse wheat cultivars were assembled as an association-mapping panel, five root traits including total root length (TRL), total root area (TRA), total root volume (TRV), average root diameter (ARD) and root dry weight (RDW) were investigated by growing in two culture conditions (Hoagland nutrient solution and pure water), and the experiments were repeated twice. Then, genome-wide association studies (GWAS) were performed for the five root traits with genotypic data derived from Wheat 660K SNP Array. Candidate genes were predicted by sequence alignment, domain analysis, and annotation information. Futhermore, kompetitive allele specific PCR (KASP) markers were developed for root traits. 【Result】The root traits varied greatly among the 189 cultivars, and the roots were thick and short cultured under Hoagland nutrient solution, while slender seminal roots and more lateral roots were observed under pure water. A total of 95 QTLs significantly associated with root traits cultured in two conditions (P<10-3) were identified by genome-wide association studies with four models of BLINK (bayesian-information and linkage-disequilibrium iteratively nested keyway), CMLM (compressed mixed linear model), FarmCPU (fixed and random model circulating probability unification) and MLM (mixed linear model). Among them, 18 QTLs were detected in both culture conditions and distributed on chromosomes of 7A, 1B, 2B, 3B, 7B, 1D, 2D, and 3D, which explained 8.68%-14.07% of phenotypic variation. Of those significant loci, 4 QTLs were similar or consistent with that reported previously, and the rest were novel ones. Haplotype analysis conducted for co-localization QTLs of 10 SNPs revealed significant differences in root traits between the two haplotypes of wheat cultivars. Based on these SNPs, KASP markers XNR7143 and XNR3707 were developed for total root volume and root dry weight, respectively. In addition, 12 candidate genes possibly regulating root development were found by mining the genes within the interval of co-localization significant SNPs. Of them, TraesCS7A02G160600, encoding 3-oxoacyl-[acyl-carrier-protein] synthase, is involved in the synthesis of root fatty acids; TraesCS1B02G401800, encoding syntaxin, plays an important role in plant tropism; TraesCS7B02G417900, encoding aldehyde oxidase, contributes to the synthesis of abscisic acid and regulation of crop root development. 【Conclusion】The root traits of wheat varied significantly among the wheat genotypes. Genome-wide association studies detected 18 significant QTLs linked with root traits simultaneously in two culture conditions, two KASP markers were developed for root traits, and 12 candidate genes related to root development were screened, which might provide reference for understanding the regulation mechanism of wheat root traits and molecular marker-assisted breeding for wheat improvement.

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    Crop Classification with Time Series Remote Sensing Based on Bi-LSTM Model
    HUANG Chong,HOU XiangJun
    Scientia Agricultura Sinica    2022, 55 (21): 4144-4157.   DOI: 10.3864/j.issn.0578-1752.2022.21.005
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    【Objective】Timely and accurate crop classification mapping is an important basis for agricultural situation monitoring. This study explores the potential of deep learning in time series remote sensing crop classification and early identification based on a bidirectional long short-term memory network model.【Method】In this paper, Yellow River Delta region was chosen as an example and a time-series NDVI dataset were constructed by using Sentinel-2 year-round available satellite images as the data source. A recurrent neural network architecture is used to build a bidirectional long short-term memory (Bi-LSTM) model for structured time-series remote sensing data to carry out crop classification, then the generalization ability of the model is evaluated. Through adjusting the length of time series, we explore the earliest identifiable time of different crops under the condition of satisfying certain mapping accuracy. 【Result】 Growth characteristics represented by time series remote sensing images have great potential to discriminate different crops. The overall accuracy of the Bi-LSTM model reached 90.9% with a Kappa coefficient of 0.892. By testing the effects of different time series lengths on crop classification, the earliest identifiable time of typical crops was obtained. The accuracy of crops such as winter-wheat and rice could improve significantly after the emergence of unique characteristics. Crops such as cotton and spring maize required complete growth sequences to ensure classification accuracy.【Conclusion】The structured feature information embedded in satellite image time series could effectively reduce crop spectral confusion at specific time periods. The Bi-LSTM model was able to consider both forward and backward temporal state information and could learn the spectral change characteristics of crops, which was excellent in the identification of confusing crops such as rice, cotton and spring maize. In addition, the deep learning model could effectively capture the variation trend on the sample in general, and showed better generalization ability and robustness in the crop multi-classification task. This study provided a feasible idea for regional crop mapping with high accuracy by integrating deep learning and remote sensing time series.

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    Development of DNA Molecular ID in Camellia oleifera Germplasm Based on Transcriptome-Wide SNPs
    LIN Ping, WANG KaiLiang, YAO XiaoHua, REN HuaDong
    Scientia Agricultura Sinica    2023, 56 (2): 217-235.   DOI: 10.3864/j.issn.0578-1752.2023.02.002
    Abstract289)   HTML75)    PDF (10200KB)(142)       Save

    【Objective】Camellia oleifera is a traditional woody oil plant and been widely cultivated in China. In order to facilitate the protection and precise management of C. oleifera cultivars and avoid the phenomenon of homonyms and synonyms, single-nucleotide polymorphism (SNP) marker database of C. oleifera cultivars was established, and a set of core SNPs were selected to construct molecular fingerprint and ID for each cultivar. 【Method】The RNA of developing seeds of 221 C. oleifera clones was extracted and RNA-seq were performed. Using C. oleifera var. ‘Nanyongensis’ genome sequence as reference, high-quality SNPs for C. oleifera were screened and the genotyping of accessions was carried out. Furthermore, the genetic diversity of C. oleifera population and subpopulations were analyzed using SNP data, including observed heterozygosity, expected heterozygosity and polymorphism information content (PIC) of the SNPs, etc. The SNP loci were further filtered by their polymorphism and location information to obtain the optimal combination of core SNP loci. Sanger-seq was performed to verify the core SNP loci. The fingerprints of each clone were formed according to the genotypes of the core SNPs. The molecular IDs of C. oleifera clones were finally constructed by combining the basic information and fingerprint of C. oleifera clones. 【Result】A total of 1 849 953 high-quality SNP loci were obtained from the transcriptomes of C. oleifera. The average values of observed heterozygosity, expected heterozygosity, fixed index, PIC and minor allele frequency of the C. oleifera population were 0.2966, 0.2462, -0.2048, 0.2073, and 0.1648, respectively. The genetic differentiation among the subpopulations of C. oleifera was minor with the high level gene flow, while the main variation was inside of the subpopulation. Filtered by PIC, LD, etc., 31 core SNP loci were screened out to distinguish all C. oleifera clones. The genotypes of all accessions in the eight core loci were further detected using Sanger-seq, and the verified rates were over 91.36%. All C. oleifera clones used in this study can be distinguished using the DNA fingerprints constructed by the 31 core SNPs. Based on the fingerprint of 31 SNP markers and the basic information of C. oleifera clones, a molecular ID of each clone, which composed of 66 digits, was formed finally. 【Conclusion】According to the polymorphism information of SNP markers, 31 core SNP loci were catched. And all C. oleifera clones were accurately distinguished. Furthermore, The DNA fingerprints of 221 C. oleifera clones were constructed by the 31 SNP markers. A unique molecular identity code for each germplasm was constructed using the DNA fingerprints and the converted serial codes from information of the C. oleifera clones. Finally, the bar codes and quick response (QR) codes are generated as the molecular ID, which can be quickly identified by the code scanning equipment.

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    Effects of Straw Returning and Nitrogen Fertilizer Types on Summer Maize Yield and Soil Ammonia Volatilization Under Future Climate Change
    ZHAO ZhengXin,WANG XiaoYun,TIAN YaJie,WANG Rui,PENG Qing,CAI HuanJie
    Scientia Agricultura Sinica    2023, 56 (1): 104-117.   DOI: 10.3864/j.issn.0578-1752.2023.01.008
    Abstract288)   HTML37)    PDF (705KB)(133)       Save

    【Objective】 Returning straw to the field and applying nitrogen fertilizer can increase crop productivity. However, under the conditions of climate change, the different management measures have great uncertainty in the nitrogen utilization of summer maize farmland. It is very important to clarify the impact of straw returning and nitrogen fertilizer types on summer maize yield and soil ammonia volatilization under future climate conditions. 【Method】 This study used the DNDC model to predict the impact of returning straw to the field and different types of nitrogen fertilizers on summer maize yield and soil ammonia volatilization accumulation in Guanzhong area under different scenarios in the future. Through the verification of field soil temperature, moisture, yield and soil ammonia volatilization test data, the DNDC model could simulate crop yields and soil ammonia volatilization accumulations under different treatments under the future climate conditions well. 【Result】Both simulation and actual measurement results showed that returning straw to the field increased summer maize yields and promoted soil ammonia volatilization under the current climate conditions. Compared with ordinary urea, slow-release fertilizers had no significant effect on summer maize yield but would significantly reduce soil ammonia volatilization accumulation. Sensitivity analysis showed that both crop yield and soil ammonia volatilization accumulation were the most sensitive to nitrogen application. Under the RCP4.5 emission scenario, the single application of stable nitrogen fertilizer (NF1) treatment and single application of urea (NF2) treatment significantly reduced the summer maize yield in 2050s-2090s and 2070s-2090s, respectively. Both the treatment of straw combined with stable nitrogen fertilizer (SF1) and the treatment of straw combined with urea (SF2) significant increased summer maize yield in 2050s-2090s; under the RCP8.5 emission scenario, NF1 significantly reduced the summer maize yield from 2070s to 2090s, and NF2 showed no significant change. The summer maize yields under SF1 and SF2 were increased significantly from 2050s to 2090s. For NF1 under the RCP4.5 emission scenario in 2050s-2090s and under the RCP8.5 emission scenario 2030s-2090s, the soil ammonia volatilization accumulation significantly increased compared with current climate conditions; for the remaining treatments, the cumulative amount of soil ammonia volatilization in future periods under different emission scenarios would be significantly reduce compared with current climatic conditions. 【Conclusion】The DNDC forecast results showed that under the climate conditions of rising temperature and CO2 concentration and changing precipitation in the Guanzhong area in the future, the returning straw to the field and applying stable nitrogen fertilizer would significantly increase the summer maize yield and reduce the accumulation of ammonia volatilization in the soil, and it was the best high-yield and emission-reducing farmland management plan. This research provided a theoretical basis for coping with climate change and the rational use of straw and nitrogen fertilizer.

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    The Relationship Between Mastication and Development of Segment Membranes in Citrus Fruits
    LI FeiFei, LIAN XueFei, YIN Tao, CHANG YuanYuan, JIN Yan, MA XiaoChuan, CHEN YueWen, YE Li, LI YunSong, LU XiaoPeng
    Scientia Agricultura Sinica    2023, 56 (2): 333-344.   DOI: 10.3864/j.issn.0578-1752.2023.02.010
    Abstract281)   HTML34)    PDF (5045KB)(101)       Save

    【Objective】 This study aimed to reveal the development of segment membrane, which contributed to citrus fruit mastication, so as to provide the theoretical basis for fruit mastication trait improvement. 【Method】 Using different citrus types (hybrid citruses including Ehime No. 30 and Nova, Okitsu Wase satsuma mandarin, navel oranges including Yuanfeng and Newhall, and pumeloes including Anjiang and Jiangyong) as reseach materials, the main physiological and biochemical properties of segment membrane were analyzed by comparisons in tissue development and cell ultrastructure. 【Result】 The rough outside but smooth inside of segment membrane occurred in all citrus types. Obviously waxy layer grew on the inside of segment membrane under which one or two cell layers with thickened cell wall arranged neatly. Cell density decreased gradually from inside to outside in segment membrane. Occurrence of wax layer in the inside and morphological changes of cells under the wax layer emblematized the maturation of citrus segment membrane. For pomelo, the thickest segment membrane linked with the worst mastication was caused from a large number of cell layers, enlarged cell size and more pectin in segment membrane. At early fruit development from squaring stage to flower withering stage, the ventricles differentiated already in the ovary, and the intervals between ventricles would develop into segment membranes. In the period, parenchyma cells in the intervals exhibited equal cell size and arranged neatly, having no segment membrane characteristics. With fruit enlargement and maturation, the segment membranes of Shatian pomelo had the most cell layers and the longest cell wall thickening period. Segment membranes of Shatian pomelo showed significantly higher pectin content than that of Yuanfeng navel orange and Juxiangzao Satsuma mandarin. Segment membranes of Yuanfeng navel orange had medium cell layers and moderate cell wall thickening period, in which protopectin was higher than that of Juxiangzao Satsuma mandarin. The segment membranes of Juxiangzao exposed the least cell layers and the shortest cell wall thickening period. In October when Juxiangzao matured, segment membrane protopectins in Shatian pomelo, Yuanfeng navel orange and Juxiangzao Satsuma mandarin were 364.22, 208.48 and 165.39 mg·g-1, respectively, with Shatian pomelo reaching 74.7% and 120.2% higher than another two varieties. 【Conclusion】 Segment membrane thickness, cell layers in segment membrane and degree of cell wall thickening associated with citrus fruit mastication. Pectin content could reflect the mastication of citrus segment membranes.

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    Candidate Gene Localization of ZmDLE1 Gene Regulating Plant Height and Ear Height in Maize
    ZHOU WenQi, ZHANG HeTong, HE HaiJun, GONG DianMing, YANG YanZhong, LIU ZhongXiang, LI YongSheng, WANG XiaoJuan, LIAN XiaoRong, ZHOU YuQian, QIU FaZhan
    Scientia Agricultura Sinica    2023, 56 (5): 821-837.   DOI: 10.3864/j.issn.0578-1752.2023.05.002
    Abstract280)   HTML40)    PDF (9613KB)(199)       Save

    【Objective】 Plant height is one of the important target traits in maize plant type breeding, which is closely related not only to mechanized grain harvesting and lodging resistance, but also to maize yield. Therefore, it is of great theoretical and breeding value to isolate QTL/gene of maize plant height and analyze its function. This study aims to locate a novel maize dwarf gene ZmDLE1, clarify its biological function, and provide important theoretical basis and gene resources for accelerating the improvement of maize plant type. 【Method】 A single recessive mutant was derived in maize inbred line LY8405, from Crop Research Institute of Gansu Academy of Agricultural Sciences, by chemical mutagenic agent Ethyl Methyl Sulfonate (EMS). A maize dwarf and low ear mutant was isolated from the M2 progeny, and the M3 and M4 progeny could stably inherit, which was named dwarf and low ear mutant1 (Zmdle1). The F2 population was constructed by hybridization with Mo17 and was identified by bulked segregate analysis-sequencing (BSA-seq) and target segment recombination exchange. Based on the Mo17 reference genome, the genes in the target region were obtained and functionally annotated to locate candidate genes.【Result】Phenotypic identification of Zmdle1 was carried out, and the phenotype of Zmdle1 at seedling stage was not significantly different from that of the control LY8405. The plant height and ear height of Zmdle1 at mature stage were reduced by 87.2 cm and 55.4 cm, respectively, accounting for about 35.0% and 62.9%, difference is extremely significant. Morphological observation showed that the decrease of internode number and the shortening of internode cell length were the main reasons for the significant decrease of plant height and ear height of Zmdle1. The genetic analysis of the mutant gene was conducted by using the F2:3 genetic populations. The Zmdle1 mutant is inherited in a 3﹕1 (χ2=2.854) ratio and is a single recessive gene. Therefore, according to the results of BSA-seq, the candidate gene ZmDLE1 was initially located in the 15 Mb region of Bin1.09-1.10 on chromosome 1 of maize. The polymorphism molecular markers were further developed using the re-sequencing results of Mo17 and Zmdle1, and the target gene was accurately cloned by map-based cloning. Finally, the candidate genes were mapped to the size range of 600 kb, and there were 16 candidate genes in this range. By comparing the re-sequencing data, it was found that Zm00001d033231 gene changed into A at the 2062 position G, which resulted in amino acid changing from glycine to serine, and the transcription level expression was significantly reduced compared with LY8405. Zm00001d033234 changed from T to C at the 223rd position leading to the 75th amino acid changed from serine to proline, and there was no significant difference in transcription level. Through association analysis of natural populations and the predicted genes for functional annotation, it was found that Zm00001d033231 and Zm00001d033234 were related to the growth and development of maize. 【Conclusion】 The candidate gene ZmDLE1 in the Bin1.09 region at the end of chromosome 1, was identified to effectively regulate maize plant height and ear height, and the target region was reduced to 600 kb by fine localization. Association analysis showed that Zm00001d033231 was genetic locus significantly associated with plant height within the target region.

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    Genome-Wide Identification and Expression Analysis of DIR Gene Family in Cucumber
    ZHANG KaiJing, HE ShuaiShuai, JIA Li, HU YuChao, YANG DeKun, LU XiaoMin, ZHANG QiAn, YAN CongSheng
    Scientia Agricultura Sinica    2023, 56 (4): 711-728.   DOI: 10.3864/j.issn.0578-1752.2023.04.010
    Abstract274)   HTML98)    PDF (9399KB)(174)       Save

    【Objective】 Based on the cucumber (Cucumis sativus L.) genome information and transcriptome sequencing big-data, the DIR gene family in cucumber was identified with bioinformatics methods, and the expression pattern analysis of DIR family genes in different tissues and stresses response were analyzed. It would lay an important foundation for further study on the biological function of cucumber DIR genes. 【Method】 With the reported HMM model file of DIR gene, the probable DIR genes ID from the cucumber protein database was firstly identified using HMMSearch program in the HMMER software package. The cucumber DIR genes were ultimately verified using online tools Pfam and SMART. The tools of ExPASy, TBtools, GSDS, MEME, MEGA, MCScanX and Circos were used to analyze the physicochemical characteristics, chromosomal distributions, gene structure, phylogenetic tree and synteny of cucumber DIR genes. Based on cucumber transcriptome sequencing big-data of different tissues and under different stresses, transcriptome sequencing analysis was re-analyzed using cucumber V3 version genome information. The data of cucumber DIR genes in different transcriptome sequencing analysis were retrieved. The expression heatmaps of DIR gene family were drawn using TBtools software, and the expression patterns of cucumber DIR genes in different tissues and stresses response were analyzed. 【Result】 Total of 23 DIR genes were identified from cucumber genome, which distributed to 7 chromosomes. The number of amino acids of these DIR genes ranged from 78 to 684, and the molecular weight ranged from 8.70 to 73.82 kD. Phylogenetic analysis divided the cucumber DIR genes into 3 subgroups, the structure and motif of the genes in each subgroup were similar. Synteny analysis showed that the 12 cucumber DIR genes were collinearity with 19 Arabidopsis DIR genes and with 27 kinds of linear relationships, and 12 cucumber DIR genes were collinearity and with 11 rice DIR genes with 19 kinds of linear relationships. While only 8 cucumber DIR genes were conservative, which were not collinearity with any DIR gene in Arabidopsis and rice. Tissue-specific expression analysis revealed that some cucumber DIR genes had low or no expression levels in all tissues including root, stem, flower, fruit, leaf and so on, some cucumber DIR genes had high expression levels in all tissues, and some DIR genes had specific expression levels in some tissues, but no or low expression levels in other tissues. This suggested that different cucumber DIR genes had tissue specific expression patterns. The expression profiles analysis of cucumber DIR genes under biotic and abiotic stresses conditions revealed that cucumber DIR gene, CsaV3_4G023490, were up-regulated expression in response to all stresses, which meant this gene played an important role in the process of cucumber growth and development. 【Conclusion】 Total of 23 DIR genes were identified in cucumber, which were divided into 3 subgroups. The gene members in each subgroup were highly conserved, and the gene structure and protein conserved domain were different among 3 subgroups. The expression patterns of cucumber DIR genes in different tissues and stresses response were different, which coordinately regulated the growth and development of cucumber.

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    Evaluation of Resistance to Leaf Scald Disease in Different Sugarcane Genotypes
    DU JinXia,LI YiSha,LI MeiLin,CHEN WenHan,ZHANG MuQing
    Scientia Agricultura Sinica    2022, 55 (21): 4118-4130.   DOI: 10.3864/j.issn.0578-1752.2022.21.003
    Abstract273)   HTML55)    PDF (2126KB)(143)       Save

    【Objective】Sugarcane leaf scald disease is an important bacterial disease affecting sugarcane yield. Selection of disease-resistant genotypes can effectively reduce the incidence of this disease. This study aimed to explore the leaf-scald resistance of sugarcane genotypes, standardize resistance evaluation method, and provide a basis for the selection and utilization of germplasm resources of sugarcane. 【Method】Xanthomonas albilineans JG43 isolated from Guitang 46, was used as inoculum on 70 different sugarcane genotypes using the decapitation method by placing 500 mL of bacterial suspension on the surface previously cut above the apical meristem with scissors dipped in the inoculum suspension of 108 CFU/mL. The disease incidence (IC) was calculated at 14, 28, 42, 56, and 70 days post-inoculation (Dpi). The disease index (DI) and the area under the disease progress curve (AUDPC) were calculated according to the disease severity of leaf scald in sugarcane. Variance, principal component, and discriminant analysis were performed using SPSS 25.0 software. Among them, a general linear model procedure (PROC) and the square sum model of type III were used to analyze the variance, with IC, DI and AUDPC as dependent variables, genotype, block and days post-inoculation as fixed factors. After the original data were processed by standardization (Z-score), principal component analysis was carried out by KOM and Bartlett sphere test. The Euclidean metric was calculated for cluster analysis using the WPGMA method of DPS 9.50 software. The discriminant analysis was performed to evaluate the clustering results according to Fisher’s criterion. 【Result】Some genotypes displayed white pencil lines at 14 dpi, then gradually expanded to the edge at 28 dpi. The leaves began yellowing or albinism from the edge to the veins at 42 dpi, then curled inward and died at 56 dpi. The severely infected plant withered and eventually died at 70 dpi. Variance analysis exhibited highly significant effects for IC, DI, and AUDPC among genotype (Gen), days post-inoculation (Dpi), and their interactions effect (Gen × Dpi) (P<0.01). Approximately 42% of the total sum of square was attributed to Dpi effect, indicating significant differences among genotypes resistance across the days post-inoculation. At 56 dpi, the disease reached a steady plateau, and the data in this period could be better divided among sugarcane genotypes. The results of discriminant and cluster analysis showed that 70 genotypes were divided into five different groups, including 15 highly resistant, 14 resistant, 15 moderate, 11 susceptible, and 15 highly susceptible genotypes. 【Conclusion】The resistance of sugarcane genotypes to leaf scald was assessed using the decapitation method, the IC, DI and AUDPC at 56 dpi were used as the evaluation indicators. The combined method of clustering and discriminant analysis could improve the accuracy of clustering results. Fifteen genotypes of high resistance to leaf scald were assessed and used for the sugarcane breeding program in China, including Zhongzhe 9, Zhongzhe 4, Zhongzhe 2, GUC19, GUC8, Yunrui 03-103, Yunrui 05-649, Yunrui 05-182, Yunrui 05-367, Yunrui 89-159, Funong 11601, Funong 09-4059, Guitang 02-467, Guitang 08-297, ROC22.

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    The Comparison of Ammonia Volatilization Loss in Winter Wheat- Summer Maize Rotation System with Long-Term Different Fertilization Measures
    YI YingJie, HAN Kun, ZHAO Bin, LIU GuoLi, LIN DianXu, CHEN GuoQiang, REN Hao, ZHANG JiWang, REN BaiZhao, LIU Peng
    Scientia Agricultura Sinica    2022, 55 (23): 4600-4613.   DOI: 10.3864/j.issn.0578-1752.2022.23.003
    Abstract269)   HTML32)    PDF (570KB)(139)       Save

    【Objective】 Based on a long-term positioning test platform, the differences of annual ammonia volatilization loss of soil nitrogen in wheat-maize rotation system under different fertilization treatments were compared, aimed to provide a theoretical basis for reducing nitrogen volatilization loss and improving fertilizer use efficiency.【Method】 From 2019 to 2021, the winter wheat variety Shimai 15 and summer maize variety Zhengdan 958 were used as experimental materials in this study. With no nitrogen fertilizer applied as the control (CK), the two kinds of nitrogen fertilizer types (organic manure: M; urea: U) and two N application rates (380 kg N·hm-2: M1, U1, U2M2, and 190 kg N·hm-2: U2, M2) were set, and the distribution of N fertilizer between two crops was 47.4% for wheat and 52.6% for maize. The venting method was used to compare the differences in annual ammonia volatilization rate, cumulative loss, grain yield, and nitrogen use efficiency in a wheat-maize rotation system under different fertilization treatments.【Result】 Different fertilization treatments significantly affected soil ammonia volatilization in the two growing seasons. The soil ammonia volatilization mainly occurred 0-7 days after fertilization during the annual year in the wheat and maize crops, and the difference between the treatments gradually became smaller. The annual ammonia volatilization loss ranged from 8.6 to 79.4 kg N·hm-2. The highest ammonia volatilization loss was 79.4 kg N·hm-2 under U1 treatment, which was 18.5%, 111.7%, 162.3%, 20.5%, and 825.7% higher than that under U2, U2M2, M1, M2, and CK, respectively. The high nitrogen application rate increased soil ammonia volatilization loss, and the loss of inorganic nitrogen fertilizers was greater than that of organic fertilizers. The annual nitrogen fertilizer ammonia volatilization loss rate under U2M2, M1, and M2 treatment was 80.9%, 40.8%, and 61.3% lower than that under U1, respectively. It was indicated that the organic and inorganic fertilizers combined application or single organic fertilizers application could significantly reduce ammonia volatilization losses. The annual grain yield under U2M2 treatment was the highest, which was 24 621.8 kg·hm-2, and was 10.1%, 24.7%, 11.7%, and 32.7% higher than that under U1, U2, M1, and M2, respectively. The annual nitrogen utilization efficiency under U2M2 treatment was 52.6%, which was 11.3%, 4.1%, 13.4%, and 10.7% higher than that under U1, U2, M1, and M2, respectively. U2M2 treatment reduced the ammonia volatilization loss and simultaneously increased the grain yield and nitrogen use efficiency, which was an ideal fertilization strategy for the annual rotation of winter wheat and maize.【Conclusion】 The application of organic fertilizer could significantly reduce the annual ammonia volatilization loss of the wheat-maize rotation system, and increase the annual grain yield and nitrogen fertilizer use efficiency. Considering the source of organic fertilizer and the convenience of application, the organic and inorganic fertilizers combined application could be used as the main fertilization method to reduce the loss of ammonia volatilization and to improve the efficiency of nitrogen fertilizer use efficiency in wheat-maize rotation production system.

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    Genome-Wide Identification and Expression Analysis of XTH Gene Family in Peach Fruit During Storage
    GUO ShaoLei, XU JianLan, WANG XiaoJun, SU ZiWen, ZHANG BinBin, MA RuiJuan, YU MingLiang
    Scientia Agricultura Sinica    2022, 55 (23): 4702-4716.   DOI: 10.3864/j.issn.0578-1752.2022.23.011
    Abstract269)   HTML48)    PDF (5788KB)(115)       Save

    【Objective】 The aim of this study was to identify members of the XTH gene family from peach, and to analyze the expression of PpXTHs in peach fruit with different textures during storage, which not only provided data for the research on the candidate PpXTHs involved in peach fruit softening, but also laid the foundation for further study on the PpXTHs function in peach fruit softening.【Method】 The HMM profiles of the Glyco_hydro_16 domain and XET_C domain were used to search all XTH proteins with the Hmmer 3.1 software in the peach protein database. The molecular weight, theoretical isoelectric point and other physicochemical properties were then predicted by the online tool ProtParam. PpXTHs subcellular localization were predicted by the online software Plant-mPLoc. The MEGA 11 software was used to construct a phylogenetic tree. The online tool MEME was used to analyze conserved motifs, the conserved motifs, conserved protein domains and gene structure maps were draw by Tbtools. According to the PpXTH gene family location information, chromosome mapping was carried out with MapChart software. The expressions of PpXTHs in peach fruit with different textures during storage were monitored by qRT-PCR..【Result】 A total of 27 PpXTH genes were systematically identified from peach, which were distributed on seven chromosomes. Based on the phylogenetic tree, the ancestral group, Ⅰ/Ⅱ subfamily, ⅢA subfamily and ⅢB subfamily were classified. In addition, according to the analysis of protein domains, all PpXTH gene family proteins had Glyco_hydro_16 and XET_C conserved domain. The results from qRT-PCR analysis showed that PpXTH33 belonging to the ⅢB subfamily was upregulated as the storage period increased in melting peach fruit, with the expression being markedly higher than that during the storage period of stony hard peach fruit. The positive clone sequencing was consistent with the coding sequence of the Prunus persica reference genome with a length of 924 bp for a 307 amino acid sequence. The PpXTH33 combined with green fluorescent protein may mainly located in the cell wall and nucleus detected by confocal laser scanning microscopy..【Conclusion】 All 27 PpXTHs protein structures contained two highly XTH conserved domains and the genes were distributed on seven chromosomes. The expression characteristics of PpXTH33 in peach fruit with different flesh textures during storage suggested that PpXTH33 was closely associated with peach fruit softening during storage.

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    Genome-Wide Association Analysis of the Changes in Oil Content and Protein Content Under Drought Stress in Brassica napus L.
    HU Sheng,LI YangYang,TANG ZhangLin,LI JiaNa,QU CunMin,LIU LieZhao
    Scientia Agricultura Sinica    2023, 56 (1): 17-30.   DOI: 10.3864/j.issn.0578-1752.2023.01.002
    Abstract269)   HTML48)    PDF (4862KB)(141)       Save

    【Objective】 Drought is one of the most adverse abiotic stresses that hinder growth and development of Brassica napus L., threatening its yield and quality. In this study, we identified the candidate genes that influence oil and protein content changes according to the results of the genome wide association mapping (GWAS) and differentially expressed genes (DEGs) under drought stress in B. napus. 【Method】 A natural population comprising 183 B. napus lines under drought stress across two years was genotyped with a Brassica 60K Illumina Infinium SNP array to perform GWAS. Combined with drought stressed seed transcriptome data from different treatment periods, the candidate genes related to the changes in oil and protein contents under drought stress were identified. 【Result】 The analysis showed that the best model for phenotypic data analysis in 2 years was mainly the Q or naïve model, and a total of 38 significant associated loci were detected (P<1/31597 or P<1/31278). By integrating GWAS and transcriptome results, 256 common genes were selected, and by comparing the database information of B. napus and Arabidopsis thaliana, 25 related candidate genes were identified. These genes, including transcription factors (e.g., bZIP transcription factor GBF6, TALE transcription factor ATH1, MYB-like Domain transcription factor MYBD, NAC transcription factor ANAC029, ERF transcription factor ERF111), related kinases (e.g., PIP5K1, PFK7), related proteins (e.g., seed stores protein CRU3, chloroplast protein DG238 and CP12, stress-responsive proteins HUP26 and M10), are involved in multiple biological processes such as photosynthetic reaction, substance transport, and stress response. For instance, oil-related protein kinase CIPK9, ABCA9 transporter, storage-related protein CRU3, may provide basis for explaining the changes in oil and protein contents of B. napus under drought stress. 【Conclusion】 The 25 identified candidate genes may affect the accumulation of protein and oil contents under drought stress during the seed development in B. napus.

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    Identification of the Root-Specific Soybean GmPR1-9 Promoter and Application in Phytophthora Root-Rot Resistance
    YAN Qiang,XUE Dong,HU YaQun,ZHOU YanYan,WEI YaWen,YUAN XingXing,CHEN Xin
    Scientia Agricultura Sinica    2022, 55 (20): 3885-3896.   DOI: 10.3864/j.issn.0578-1752.2022.20.002
    Abstract268)   HTML57)    PDF (3529KB)(144)       Save

    【Objective】The objective of this study is to identify the root-specific promotors and the core regulatory sequence of soybean. Then evaluate the potential application of the synthetic promoter in Phytophthora root-rot resistance. 【Method】The genes which specifically expressed in roots with high expression levels were screened based on the transcriptome date of soybean root, stem and leaf tissues in the seedling stage. Based on the distribution of the cis elements, the promoter truncation approach was used to map the minimal promoter controlling root specific expression in soybean hairy roots. The obtained minimal promoter fragment was concatenated with the Phytophthora inducible promoter elements p4XD to construct the synthetic promoter. The synthetic promoter driven over-expression of Phytophthora resistance related gene GmNDR1 in soybean hairy roots, then the resistance level of transgenic tissue to Phytophthora and the expression profiles of GmNDR1 during the interaction had been analyzed. Furthermore, the transgenic Nicotiana benthamiana plants were generated to evaluate the resistance at plant level. 【Result】Though screening, six soybean PR1 homologues with significant root specific expression manner were identified, and GmPR1-9 had the highest promoter activity. Numbers of root specific expression related cis elements were identified in promoter sequence using the online tool PLACE. Truncation analysis of the promoter showed that serial 5’ end deletions L1, L2, L3, L4 and L5 had different GUS activities. The L5 (-166 to -1) fragment had 80% activity of the full-length promoter, and was able to drive GUS expression in roots of transgenic N. benthamiana. GUS enzyme activity was almost undetectable in three 3’ end deletions R1, R2 and R3, and the double terminal deletion mutant M1. When the fusion promoter p4XD-L5 driven GmNDR1 expression in soybean hairy roots, the resistance to P. sojae was significantly enhanced. The disease severity and lesion length were significantly reduced in the over-expression hairy roots when compared with control, and the relative biomass of Phytophthora decreased by 66.5% at 48 h post inoculation. GmNDR1 maintained high expression level in over-expression tissues, with 39.2 times of that in control tissues. The expressions were further up-regulated after inoculation, and reached the highest level at 36 h. In p4XD-L5::NDR1 transgenic N. benthamiana plants, the expression of GmNDR1 was significantly higher in roots than that in stems and leaves. Fifteen days after P. capsica inoculation, the plant height, root length and fresh weight of GmNDR1 over-expression plants were significantly higher, and meanwhile the leaf wilting rate and lesion length were significantly lower. 【Conclusion】This study obtained a soybean root specific promoter and identified the core regulation sequence. The strategy which driven the expression of GmNDR1 by the synthetic promoter p4XD-L5 combined the inducible and tissue-specific promoter core elements can significantly enhance the resistance of transgenic soybean hairy roots and Nicotiana benthamiana plants to Phytophthora pathogens.

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    Construction of A Comprehensive Evaluation System and Screening of Cold Tolerance Indicators for Cold Tolerance of Cotton at Seedling Emergence Stage
    SHEN Qian,ZHANG SiPing,LIU RuiHua,LIU ShaoDong,CHEN Jing,GE ChangWei,MA HuiJuan,ZHAO XinHua,YANG GuoZheng,SONG MeiZhen,PANG ChaoYou
    Scientia Agricultura Sinica    2022, 55 (22): 4342-4355.   DOI: 10.3864/j.issn.0578-1752.2022.22.002
    Abstract267)   HTML55)    PDF (2550KB)(145)       Save

    【Objective】 In this study, the purpose was to comprehensively evaluate the cold tolerance of cotton varieties (lines) at seedling emergence stage, establish a reliable evaluation model, screen and identify indicators, and provide a simple and effective evaluation method for the selection and identification of cold-tolerant varieties in cotton.【Method】200 upland cotton varieties (lines) were used to test hypocotyl length, root length and 100-grain weight, etc. under three treatments of constant chilling (CC), diurnal variation of chilling (DVC) and normal conditions. A combination of integrated cold tolerance coefficient difference analysis, frequency analysis, drop analysis, principal component analysis, cluster analysis, and multiple regression analysis were used to classify their cold tolerance types, establish cold tolerance prediction models, and screen evaluation parameters. 【Result】The variation of each parameters at normal conditions were minor fluctuations ranging from 3.12% to 18.89%. The seedling emergence rate was above 85.00%, which had high viability and could be used for subsequent cold tolerance analysis. The variability of each parameter within the accessions increased under chilling stress, ranging from 7.14%-108.33%, and the most variable parameter were root length under CC condition and germination index under DVC condition. Principal component analysis converted the 14 parameters under chilling stress and 100-grain weight measured into six mutually independent composite indicators, representing 74.98% of the total data information. The comprehensive cold tolerance evaluation value (D) was calculated by the affiliation function method and then clustering analysis was performed. 200 cotton varieties (lines) were divided into five categories according to their cold tolerance, with 2 of the group Ⅰ being strongly cold tolerant, 42 of the group Ⅱ being cold tolerant, 69 of the group Ⅲ being medium cold tolerant, 83 of the group Ⅳ being more sensitive, and 4 of the group Ⅴ being sensitive, of which Xinluzhong 16 was the most cold-tolerant material. A multiple regression analysis was applied to establish a prediction model for cold tolerance of cotton at seedling emergence as Y=-4.10+0.58X4+0.40X14+0.32X1+0.22X5 (R2=0.92), and four parameters for cold resistance evaluation were confirmed, namely total length of seedling, emergence rate, and dry weight under CC stress, germination rate under DVC stress. The cold-tolerant varieties (lines) had higher seedling emergence rates of early sowing experiment in the field, which were basically consistent with the results of the indoor results. 【Conclusion】 It is feasible to use CC and DVC stress combined with multivariate statistical analysis to evaluate the cold tolerance of cotton at seeding stage, and total length of seedling, emergence rate, and dry weight under CC stress, germination rate under DVC stress can be used as evaluation parameters.

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    Correlation Between Stomatal Characteristics and Cold Resistance of Brassica napus L.
    FAN JunQiang, WU JunYan, LIU LiJun, MA Li, YANG Gang, PU YuanYuan, LI XueCai, SUN WanCang
    Scientia Agricultura Sinica    2023, 56 (4): 599-618.   DOI: 10.3864/j.issn.0578-1752.2023.04.002
    Abstract265)   HTML40)    PDF (2779KB)(159)       Save

    【Objective】 The characteristics of the stomatal movement of winter Brassica napus with different cold resistance in northern China in a low-temperature environment were analyzed, and the relationship between cold resistance and stomatal movement was clarified, which provided a basis for analyzing the cold resistance mechanism of winter Brassica napus and cultivating strong cold resistance varieties. 【Method】 The physiological indexes of 14 winter Brassica napus varieties under semi-lethal temperature and low temperature were determined to judge the difference in cold resistance. At the same time, 12 stomatal indexes of the lower epidermis of the leaves of the plants treated at 24℃ for 12 h, 0℃ for 1 h, and 0℃ for 12 h were determined. Stomatal evaluation indexes significantly related to cold resistance evaluation indexes were screened by correlation analysis. 【Result】 (1) According to the results of semi-lethal temperature determination, the cold resistance of the tested varieties was identified as gau-1 (-8.06)>gau-24 (-7.83)>gau-30 (-7.58)>gau-39 (-7.44)>ts309 (-7.28)>ts312 (-7.08)>nts158 (-6.81)>npz269 (-6.62)>Tianyou 14 (-5.98)>16-2444 (-5.4)>17-2251 (-5.13)>Tianyou 2266 (-4.8)>Tianyou 2238 (-4.6)>Tianyou 2288 ( -4.38 ). According to the comprehensive evaluation value of physiological indexes, the results of cold resistance were gau-1 (0.990)>gau-24 (0.876)>gau-30 (0.693)>gau-39 (0.644)>ts309 (0.534)>ts312 ( 0.463)>nts158 (0.439)>npz269 (0.388)>Tianyou 14 (0.352)>16-2444 (0.307)>17-2251 (0.282)>Tianyou 2266 (0.236)>Tianyou 2238 (0.126)>Tianyou 2288 ( 0.000). The cold resistance measured by semi-lethal temperature was consistent with the comprehensive evaluation results of physiological indexes. (2) 12 stomatal movement-related indicators changed significantly after low-temperature treatment. The correlation analysis showed that there was no significant correlation between the 12 stomatal indexes and the semi-lethal temperature at room temperature and 0℃ after 1 h treatment. After 12 h treatment at 0℃, the stomatal pore length, area of stomatal pore, circumference of stomatal pore, stomatal apparatus length, area of stomatal apparatus, Circumference of stomatal apparatus, and stomatal closure rate were significantly correlated with cold resistance. The semi-lethal temperature was significantly correlated with the comprehensive evaluation value (Z) of stomata, and the correlation coefficient was-0.572. 【Conclusion】 Low-temperature treatment can significantly affect the stomatal movement of winter Brassica napus, and the characteristics of stomatal closure tend to be more obvious with the extension of low-temperature treatment time. At the same time, the relative changes of stomata of different temperature-sensitive varieties were different, and the varieties with strong cold resistance had stronger ability to keep stomata open after low-temperature treatment.

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    Genetic Diversity Analysis and Comprehensive Evaluation of Sorghum Breeding Materials Based on Phenotypic Traits
    ZHANG YiZhong, ZHANG XiaoJuan, LIANG Du, GUO Qi, FAN XinQi, NIE MengEn, WANG HuiYan, ZHAO WenBo, DU WeiJun, LIU QingShan
    Scientia Agricultura Sinica    2023, 56 (15): 2837-2853.   DOI: 10.3864/j.issn.0578-1752.2023.15.001
    Abstract265)   HTML52)    PDF (644KB)(215)       Save

    【Objective】 The present study analyzed the genetic variation of phenotypic traits and genetic diversity of sorghum breeding materials. Additionally, the study explored a comprehensive method for the evaluation of germplasm materials and screening of excellent sorghum germplasm to provide an important basis for sorghum germplasm innovation and variety selection.【Method】 In total, 263 sorghum germplasms from different sources were used as the test materials, and 17 phenotypic traits were identified under different environments for two years. Genetic diversity of the phenotypic traits was calculated based on the Shannon-Wiener information diversity index. The sorghum germplasms were comprehensively evaluated using the correlation analysis, principal component analysis, cluster analysis, and stepwise regression. Excellent sorghum germplasms were screened according to the phenotypic comprehensive evaluation value (F value) and target traits.【Result】 Sorghum breeding materials exhibited high genetic diversity. The diversity index distribution of different traits ranged from 0.497 to 2.075, with the diversity index of spike shape being the smallest and that of spike stalk length being the largest. The coefficient of variation of seven plant height, stem diameter, panicle length, panicle stalk length, grain weight per spike, thousand grain weight, period of duration varied in different years; the smallest variation was observed in the period of duration, followed by the panicle length, whereas the largest variation was observed in grain weight per spike, followed by stem diameter. A comprehensive evaluation of the breeding materials showed that when the cumulative contribution percentage was >80%, the number of the total principal components was 11. F value of the sorghum breeding materials was calculated using the membership function method. The average F value was found to be 0.464, with the restorer line L28 having the highest F value (0.581) and the maintainer line 72B/DORADO having the lowest the F value (0.330). Through stepwise regression, a regression equation was established, with 12 traits (main vein color, ear type, ear shape, awn character, glume coating degree, grain shape, plant type, stem diameter, ear length, grain weight per ear, 1000-grain weight, and growth period) as independent variables. The equation could be used for a comprehensive evaluation of the phenotypic traits of breeding materials of sorghum breeding materials. Based on F value clustering, 263 materials were divided into six groups. Among these, 33 materials in group Ⅳ exhibited excellent agronomic characteristics and high F value, which could be used as parent materials for material innovation and cross breeding.【Conclusion】 Sorghum phenotypic traits exhibit rich genetic variation and high genetic diversity. A total of 33 excellent germplasms were obtained. Using multivariate statistical analysis is a feasible approach to comprehensively evaluate sorghum germplasm.

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    Evolution of Human H9N2 Avian Influenza Virus in China from 1998 to 2021
    WANG YanWen,WANG MengJing,ZHANG Hong,GAO XinXin,GUO Jing,LI XuYong
    Scientia Agricultura Sinica    2022, 55 (20): 4075-4090.   DOI: 10.3864/j.issn.0578-1752.2022.20.017
    Abstract264)   HTML37)    PDF (4859KB)(79)       Save

    【Objective】 The epidemiological characteristics of H9N2 avian influenza virus were clarified by analyzing the onset time, province, age, gender and other information of human cases infected with H9N2 avian influenza from 1998 to 2021 in China. By analyzing the genetic characteristics of human H9N2 subtype avian influenza virus, the genetic evolution law of human H9N2 subtype avian influenza virus was elucidated. This study could provide data support for the early warning and control of H9N2 subtype avian influenza virus cross-species transmission. 【Method】 According to the case report, literature data and gene bank, the case information and strain sequence data of human infection with H9N2 subtype avian influenza virus in China from 1998 to 2021 were obtained. The infection cases were analyzed from the time distribution, space distribution, gender and age distribution, and the epidemiological characteristics of human-derived H9N2 subtype avian influenza virus infection were found. The MegAlign software in DNASTAR were used to analyze Nucleotide sequence of the homology of various gene fragments of human H9N2 isolates, a phylogenetic tree was constructed by MEGA7.0 software, and the key sites of viral proteins were analyzed. The genetic evolution trend of viral proteins and the variation of key amino acid sites were clarified. The 2019-2021 H9N2 subtype avian influenza virus nucleotide sequence in China was downloaded from the GISAID website. After mafft alignment, the key amino acid site mutation differences between human and avian H9N2 viruses were examined in MEGA7.0, the potential risks brought by current human and avian H9N2 viruses were revealed. 【Result】 From1998 to 2021, a total of 71 cases of human infection with the H9N2 subtype avian influenza virus occurred in China. From the spatial distribution analysis, the cases were distributed in 16 provinces and cities, of which 91.55% of the cases were from 12 provinces and cities in the south. In terms of time, the number of reported infections has been on the rise after 2013, and the cumulative number of infections from 2013 to 2021 accounted for 61.97% of the total number of infections. From the analysis of gender and age distribution, the ratio of male to female was 1:1.68. Human infection with H9N2 virus was mainly seen in infants and young children, accounting for 74.14% of the total number of cases. Genome comparison analysis of human H9N2 viruses found that these viruses belonged to the Eurasian branch, but the nucleotide sequence of homology of these viruses gene fragments was quite different. The nucleotide homology of HA, NA, PB2, PB1, PA, NP, M, and NS were 75.3%-100%, 80.1%-100%, 78.7%-100%, 82.5%-100%, 72.6%-100%, 74.1 -100%, 65.5%-100%, and 82.0%-100%, respectively. According to the genealogy of human isolates, 22 human isolates with complete gene fragments could be divided into 8 genotypes, genotypes in 2003, 2008, and 2013 were significantly different from genotypes in 1999. A total of 42 human H9N2 virus strains uploaded HA sequences from 1998 to 2021, and 38 of them had the mutation of Q226L in the HA protein; a total of 30 human virus strains uploaded PB2 sequence from 1998 to 2021, and 9 strains of which had the mutation of E627V in the PB2 protein, 1 of which had the mutation of E627K in the PB2 protein; the 701 site of the PB2 protein of one virus had the mutation of D701N, a total of 31 virus strains uploaded NS and M sequence from 1998 to 2021, the 42nd positions of the NS1 protein were all S, and the amino acids at positions 30th and 215th of the M1 protein were D and A, respectively. 【Conclusion】 Since 2013, the number of human infections with H9N2 subtype avian influenza reported in China has been on the rise, with significant differences in geographic, age and gender distribution. Since 1998, the genetic homology between human H9N2 isolates was quite different, and the viral gene rearrangement between different branches was frequent, forming a complex genotype. It was suggested that the H9N2 subtype avian influenza virus was constantly evolving. Mutations in key amino acid sites of human H9N2 virus and mutation rate of human viruses was higher than avian H9N2 viruses from 2019 to 2021, suggesting that the potential of H9N2 subtype avian influenza virus to infect humans was gradually increasing. This result enriched the knowledge of human H9N2 virus and provided an important reference for the prevention and control of H9N2 subtype avian influenza virus.

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    Effects of Two Mechanical Planting Methods on the Yield and Quality of High-Quality Late Indica Rice
    GUO BaoWei,TANG Chuang,WANG Yan,CAI JiaXin,TANG Jian,ZHOU Miao,JING Xiu,ZHANG HongCheng,XU Ke,HU YaJie,XING ZhiPeng,LI GuoHui,CHEN Heng
    Scientia Agricultura Sinica    2022, 55 (20): 3910-3925.   DOI: 10.3864/j.issn.0578-1752.2022.20.004
    Abstract259)   HTML4)    PDF (569KB)(142)       Save

    【Objective】The experiment was conducted to clarify the differences in the yield and quality of double cropping high-quality late indica rice and the selection criteria for variety tapes under mechanical transplanting (MT) and mechanical direct seeding (MS).【Method】Early-maturing late indica rice, medium-maturing late indica rice, moderately late-maturing late indica rice, late-maturing late indica rice and extremely late-maturing late indica rice were used as materials, and two planting methods including MT and MS were set to study the yield and quality characteristics of high-quality late indica rice.【Result】(1) The seed setting rate and the number of spikelets in the population of the high-quality late indica rice under MT were significantly higher than that under MS, and the 1000-grain weight under MT also increased, finally the actual yield was significantly increased. For MT, the medium-maturing late indica rice had the highest yield, followed by moderately late-maturing late indica rice; while for MS, the early-maturing late indica rice had the highest yield, followed by medium-maturing late indica rice. (2) Compared with MS, the processing quality of high-quality late indica rice varieties under MT was better for the significantly higher brown rice rate, milled rice rate and head rice rate, but the appearance quality deteriorated because of the increased chalky rice rate and chalkiness degree. The cooking quality improved for higher gel consistency, breakdown, taste value and lower amylose content. The highest brown rice rate, milled rice rate, and head rice rate were all found in medium-maturing late indica rice under two planting methods, chalky rice rate and chalkiness degree among different varieties showed the trend of extremely late-maturing late indica rice

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    The Characteristics of Soil Nutrients and Soil Enzyme Activities During Wheat Growth Stage Under Different Tillage Patterns
    ZHU ChangWei,MENG WeiWei,SHI Ke,NIU RunZhi,JIANG GuiYing,SHEN FengMin,LIU Fang,LIU ShiLiang
    Scientia Agricultura Sinica    2022, 55 (21): 4237-4251.   DOI: 10.3864/j.issn.0578-1752.2022.21.011
    Abstract258)   HTML51)    PDF (591KB)(159)       Save

    【Objective】This study was aimed to select the optimum tillage pattern by investigating the dynamic changes of different tillage patterns on soil nutrients, microbial biomass, and enzyme activities during different wheat growth stages in fluvo-aquic soil in Huang-Huai Plain.【Method】The field experiment was carried out from 2016 to 2019. Five rotation tillage modes were set as: (1) Continuous Rotary Tillage (RT-RT-RT); (2) Deep tillage-Rotary tillage-Rotary tillage (DT-RT-RT); (3) Deep tillage-Rotary tillage-Shallow rotary tillage (DT-RT-SRT); (4) Deep tillage-Shallow rotary tillage-Shallow rotary tillage (DT-SRT-SRT); (5) Deep tillage-Shallow rotary tillage-Rotating tillage (DT-SRT-RT). Three years is a cycle. In the third year of the 3-year cycle, i.e. 2019, 0-40 cm soil layer samples were taken at the wheat greening stage (GS), jointing stage (JS), filling stage (FS), and maturity stage (MS). The contents of alkali hydrolyzed nitrogen (AN), available phosphorus (AP), available potassium (AK), soil microbial biomass carbon (SMBC), soil microbial biomass nitrogen (SMBN), and the activities of urease, invertase, and neutral phosphatase in different soil layers were measured and analyzed.【Result】All soil indicators were decreased with the soil depths during the whole wheat growth stage. Compared with RT-RT-RT, the increment of available nutrients contents at 20-40 cm soil layer were significantly higher than those at 0-20 cm soil layer under the treatments with deep tillage combined with rotary tillage or shallow rotary tillage, but which presented few effects on soil microbial biomass and enzyme activities under soil layers compared with the effects on soil available nutrients. The dynamic changes of each soil indicators under different treatments during the wheat main growth stages were consistent with the growth and fertilizer requirements of crops. The AP, AK, SMBC, SMBN, urease, neutral phosphatase activities were showed an “N” type trend and reached to peak at the jointing stage. The sucrase activity was gradually increased with the growth stage. In 0-20 cm soil layer, the contents of AN, AP and AK under DT-SRT-RT treatment at the jointing stage were significantly higher than that under other treatments, and the highest value were 91.74 mg·kg-1, 27.17 mg·kg-1 and 139.81 mg·kg-1, respectively. The AN and AP were significantly affected by rotation tillage patterns and soil depths. While the AK was affected by wheat growth stages, soil layers, and rotation tillage patterns, but the interaction among them was not obvious. During the whole growth period, compared with RT-RT-RT, in 0-40 cm soil layer, the SMBC and SMBN content under DT-RT-RT and DT-SRT-RT treatments were higher. The DT-SRT-RT treatment could significantly increase the activities of soil urease, invertase and neutral phosphatase, and their growth rates were between 3.79%-27.69%, 12.29%-36.10% and 8.61%-35.91%, respectively. In the whole wheat growth period, the soil microbial biomass and enzyme activities were significantly affected by different soil depth and rotation tillage mode, but the interaction between them on SMBN content, invertase, and neutral phosphatase activity was not significant. The wheat yield under the other treatments in 2019 was higher than that under RT-RT-RT, and the highest one was 6 557 kg·hm-2 under DT-SRT-RT.【Conclusion】During this experimental period, in Fluvo-aquic soil in Huang-Huai Plain, the DT-SRT-RT treatment had the best effect on improving available nutrients contents, SMBC, SMBN, and soil enzyme activity, thereby further ensuring the high yield of wheat.

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    Effects of Irrigation Amount on Berry Development and Aroma Components Accumulation of Shine Muscat Grape in Root-Restricted Cultivation
    ZHANG KeKun,CHEN KeQin,LI WanPing,QIAO HaoRong,ZHANG JunXia,LIU FengZhi,FANG YuLin,WANG HaiBo
    Scientia Agricultura Sinica    2023, 56 (1): 129-143.   DOI: 10.3864/j.issn.0578-1752.2023.01.010
    Abstract256)   HTML36)    PDF (601KB)(141)       Save

    【Objective】The effects of different irrigation amounts on grape berry quality, aroma component accumulation, and the expression level of aroma compounds biosynthetic genes were studied to determine the relationship between irrigation patterns and sensory quality of table grapes, so as to provide a reference for choosing the optimal irrigation amount in root-restricted cultivation. 【Method】The table grape cultivar Shine Muscat was used as the test material, the control group (CK), the mild water deficit group (DI-1), and the severe water deficit group (DI-2) were set up to systematically compare the effect of different irrigation amounts on the morphological indicators, appearance color indicators, aroma components, and expression levels of terpene biosynthetic genes of grape berries. 【Result】Irrigation amount could affect the morphological and texture characteristics of grape berries. Comparing with other treatments, the longitudinal diameter of grape berries at harvest time was not significantly affected by irrigation amount, while the horizontal diameter and single berry weight of grape berries in deficit irrigation group were significantly reduced. The firmness of grape pulp also decreased under the influence of deficit irrigation, especially under DI-2 group, of which the pulp firmness was significantly lower than that under other treatment groups. Meanwhile, the glucose content in the grape berries under the deficit irrigation group DI-1 and DI-2 was significantly higher than that under the control treatment, and the fructose content under the severe deficit irrigation group DI-2 was significantly higher than that under other treatments. Mild deficit irrigation of DI-1 exerted little effect on the content of total soluble solids and titratable acid in grape berries. The contents of chlorophyll and carotenoids in grape skins were decreased under the deficit irrigation treatment, and the ratio of the chlorophyll content to carotenoids content in the skins of the DI-2 group was the lowest. Additionally, the amount of irrigation also affected the accumulation of aroma components in grape berries. The terpenes compounds reached the highest content in the berries of the DI-1 group, such as limonene, phellandrene, α-pinene, γ-terpinene, (E)-β-ocimene, terpinolene, (E)-furanoxylinalool, linalool, dihydrolinalool, α-terpineol, citronellol, nerol, and geraniol, followed by the content of terpenes under the DI-2 group, and the lowest under the control group. As for esters, the total content of those compounds under the DI-1 group was the highest, followed by the control group, and the content of the DI-2 group was the lowest. For the total amount of aldehydes, the content in the DI-1 group were significantly lower than those in the control group and DI-2 group. For the total amount of higher alcohols, the content of DI-1 group was the highest, followed by DI-2 group, and the control group was the lowest. There were differences in the expression patterns of terpene biosynthesis-related genes under different irrigation conditions. The expression of VvDXS1, VvDXS2, VvDXR, VvDHR, VvPNLinNer1, VvCSLinNer, VvGwbOci, VvCSbOci and VvGwGer were up-regulated in response to water deficit. 【Conclusion】According to the accumulation of aroma components and the comprehensive score of sensory quality, the mild water deficit (60%-70% of the maximum water holding capacity in the field) could better promote the formation of aroma quality of Shine Muscat grape berries and improve their commercial value.

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    Analysis of Cross Compatibility Variation Among Diverse Sesamum Species and Biological Characteristics of the Interspecific Hybrid Progenies
    JU Ming, MIAO HongMei, HUANG YingYing, MA Qin, WANG HuiLi, WANG CuiYing, DUAN YingHui, HAN XiuHua, ZHANG HaiYang
    Scientia Agricultura Sinica    2022, 55 (20): 3897-3909.   DOI: 10.3864/j.issn.0578-1752.2022.20.003
    Abstract255)   HTML48)    PDF (4302KB)(114)       Save

    【Objective】 The research aims to explore the cross compatibility between different Sesamum species and analyze the biological characteristics of interspecies hybrid progeny so as to supply the foundation for efficient application of wild sesame species. 【Method】 A sesame cultivar Yuzhi 11 (S. indicum, 2n=26) and 4 wild Sesamum species including S. latifolium (2n=32), S. calycinum (2n=32), S. angustifolium (2n=32), and S. radiatum (2n=64) were applied to construct interspecies cross combinations using diallel hybridization method by artificial pollination in the field. Embryo rescue method was also used to obtain interspecific hybrid F1. Interspecific hybrid compatibility was compared based on hybrid capsule formation rate. Botanical characters of hybrids were observed during flowering and mature stages. Pollen fertility was assessed using Alexander staining method. Chromosome number and karyotype characteristics of root somatic cells of hybrids were observed using smear chromosome preparation technique. Specific and polymorphic SSR primers in Sesamum were used to analyze the molecular difference in interspecific hybrids.【Result】 Twenty positive and reciprocal cross combinations were constructed for the 5 Sesamum species. A total of 2091 flowers were pollinated and 370 hybrid capsules were harvested. As to the female parents with more chromosomes, hybrid capsules were more easily obtained. The cross compatibility among the 5 Sesamum species significantly varied from 1.18% (S. radiatum×S. calycinum) to 63.33% (S. calycinum×S. angustifolium). F1 plants of 9 combinations produced hybrid seeds, while the ratio of pollen sterility of F1 progeny ranged from 35.21%-100.00%. The cross S. calycinum×S. angustifolium presented the highest sterility ratio to 87.68%. Hybrid progeny exhibited the obvious heterosis over parents in plant height, plant type, and some key agronomic traits. As to the positive and reciprocal hybrid F1 derived from sesame cultivar and the wild species, leaf shape, flower shape, and flower color showed partial characters of both parents. The cross compatibility between sesame cultivar (n=13) and the 3 Sesamum species with chromosome group n=16 ranked as S. angustifolium>S. calycinum>S. latifolium. The cross compatibility between wild species S. radiatum (n=32) and the 3 species with n=16 ranked as S. calycinum>S. angustifolium>S. latifolium. Among the 5 Sesamum species, the genetic relationship between S. calycinum and S. angustifolium is relatively closest. The chromosome number of root tip cells of some hybrid plants is consistent with the theoretical value calculated from the parents. Screening results of the 3 pairs of polymorphic SSR primers indicated that 99.66% of obtained F1 plants are true hybrid. Chromosome karyotype and SSR marker screening results reflected the genetic difference and characters of Sesamum species. 【Conclusion】Among the 5 Sesamum species, the cross compatibility varies significantly and the heterosis of interspecific hybrid is obvious. Of which only S. calycinum and S. angustifolium have the relatively closest genetic relationship and could be directly applied for elite germplasm creation and interspecific hybrid breeding in Sesamum. Reproductive isolation barriers exist in other cross combinations. Some techniques including embryo rescue and molecular marker application should be used to achieve the utilization of wild Sesamum species for sesame breeding.

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    Effect of Phytochlorin Iron on Stress Tolerance to Waterlogging in Wheat
    CHU YanMeng, MAO YingChao, CAI Jian, ZHOU Qin, DAI TingBo, WANG Xiao, JIANG Dong
    Scientia Agricultura Sinica    2023, 56 (10): 1848-1858.   DOI: 10.3864/j.issn.0578-1752.2023.10.003
    Abstract255)   HTML35)    PDF (509KB)(188)       Save

    【Objective】Waterlogging stress is one of the main limiting factors for wheat production, especially in the middle and lower reaches of the Yangtze River in China. Improving the waterlogging tolerance of wheat is an important goal to achieve stable and increased yield in this region. In this study, by exploring the suitable use period and concentration of phytochlorin iron, its role in improving waterlogging stress tolerance was further evaluated mainly from the perspectives of plant photosynthesis and plant antioxidant capacity. The research results could provide the theoretical and technical support for waterlogging-resistant cultivation of wheat.【Method】Using Yangmai 16 as material, three concentrations (0.0875, 0.126, and 0.194 mmol·L-1) of phytochlorin iron were set at anthesis and grain filling stages to screen the appropriate period and concentration for achieving a significant increase in wheat yield. Based on this, the effect of phytochlorin iron on wheat tolerance to waterlogging stress at anthesis stage was further evaluated.【Result】Compared with control, treatment with a concentration of 0.126 mmol·L-1 phytochlorin iron at anthesis stage (A2) could significantly increase wheat grain yield by increasing the grain weight. Waterlogging stress at anthesis stage significantly reduced the chlorophyll content, net photosynthesis rate, and post-flowering dry matter accumulation and translocation to grain, resulting in grain yield reduction. However, compared with non-spraying treatment, AW2 treatment showed a higher photosynthetic pigment content, photosystem II stability, net photosynthetic rate. Meantime, the raised activities of antioxidant enzymes, reduced O2- production rate and H2O2 content, which showed correspondence with the reduced accumulation of malondialdehyde content, thus alleviated the damage of cell membrane lipid peroxidation and the yield reduction caused by waterlogging stress.【Conclusion】Spraying a concentration of 0.126 mmol·L-1 phytochlorin iron at anthesis stage could significantly increase wheat yield. Phytochlorin iron could alleviate the plant senescence, reduce damage to PSII, enhance the activity of antioxidant enzymes, reduce the damage of cell membrane lipid peroxidation, maintain higher photosynthetic rate, reduce the degree of yield reduction, and enhance wheat tolerance to waterlogging stress.

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