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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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    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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    Research Progress on Machine Learning for Genomic Selection in Animals
    LI MianYan, WANG LiXian, ZHAO FuPing
    Scientia Agricultura Sinica    2023, 56 (18): 3682-3692.   DOI: 10.3864/j.issn.0578-1752.2023.18.015
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    Genomic selection is defined as using the molecular marker information that covered the whole genome to estimate individual’s breeding values. Using genome information can avoid many problems caused by pedigree errors so as to improve selection accuracy and shorten breeding generation intervals. According to different statistical models, methods of estimated genomic breeding value (GEBV) can be divided into based on BLUP (best linear unbiased prediction) theory, based on Bayesian theory and others. At present, GBLUP and its improved method ssGBLUP have been widely employed. Accuracy is the most used evaluation metric for genomic selection models, which is to evaluate the similarity between the true value and the estimated value. The factors that affect the accuracy can be reflected from the model, which can be divided into controllable factors and uncontrollable factors. Traditional genomic selection methods have promoted the rapid development of animal breeding, but these methods are currently facing many challenges such as multi-population, multi-omics, and computing. What’s more, they cannot capture the nonlinear relationship between high-dimensional genomic data. As a branch of artificial intelligence, machine learning is very close to biological mastery of natural language processing. Machine learning extracts features from data and automatically summarizes the rules and use to make predictions for new data. For genomic information, machine learning does not require distribution assumptions, and all marker information can be considered in the model. Compared with traditional genomic selection methods, machine learning can more easily capture complex relationships between genotypes, phenotypes, and the environment. Therefore, machine learning has certain advantages in animal genomic selection. According to the amount and type of supervision received during training, machine learning can be classified into supervised learning, unsupervised learning, semi-supervised learning, and reinforcement learning. The main difference is whether the input data is labeled. The machine learning methods currently applied in animal genomic selection are all supervised learning. Supervised learning can handle both classification and regression problems, requiring the algorithm to be provided with labeled data and the desired output. In recent years, the application of machine learning in animal genomic selection has been increasing, especially in dairy and beef cattle. In this review, machine learning algorithms are divided into three categories: single algorithm, ensemble algorithm and deep learning, and their research progress in animal genomic selection were summarized. The most used single algorithms are KRR and SVR, both of which use kernel tricks to learn nonlinear functions and map data to higher-dimensional kernel spaces in the original space. Currently commonly used kernel functions are linear kernel, cosine kernel, Gaussian kernel, and polynomial kernel. Deep learning, also known as a deep neural network, consists of multiple layers of connected neurons. An ensemble learning algorithm refers to fusing different learners together to obtain a stronger supervised model. In the past decade, the related literature on machine learning and deep learning has shown exponential growth. And its application in genomic selection is also gradually increasing. Although machine learning has obvious advantages in some aspects, it still faces many challenges in estimating the genetic breeding value of complex traits in animals. The interpretability of some models is low, which is not conducive to the adjustment of data, parameters, and features. Data heterogeneity, sparsity, and outliers can also cause data noise for machine learning. There are also problems such as overfitting, large marks and small samples, and parameter adjustment. Therefore, each step needs to be handled carefully while training the model. This paper introduced the traditional methods of genomic selection and the problems they face, the concept and classification of machine learning. We discussed the research progress and current challenges of machine learning in animal genomic selection. A Case and some application suggestions were given to provide a certain reference for the application of machine learning in animal genomic selection.

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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
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    【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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    QTL Mapping and Molecular Marker Development of Traits Related to Grain Weight in Wheat
    ZHANG ZeYuan, LI Yue, ZHAO WenSha, GU JingJing, ZHANG AoYan, ZHANG HaiLong, SONG PengBo, WU JianHui, ZHANG ChuanLiang, SONG QuanHao, JIAN JunTao, SUN DaoJie, WANG XingRong
    Scientia Agricultura Sinica    2023, 56 (21): 4137-4149.   DOI: 10.3864/j.issn.0578-1752.2023.21.001
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    【Objective】The yield of wheat, the second-highest-yielding food product in the world, has a major impact by grain weight. This research used materials from a recombinant inbred line (RIL) population derived from Heshangtou (HST) and Longchun 23 (LC23). Based on 55K SNP genotype data, QTL mapping was performed for traits related to grain weight of wheat, and co-segregation markers of major grain length QTL were developed and verified to provide reference for molecular marker assisted selection breeding.【Method】The wheat 55K SNP microarray was used to genotype parents and RIL populations, and a high density genetic linkage map was constructed, and its correlation with Chinese spring reference genome IWGSC RefSeq v1.0 was analyzed. QTL mapping of traits related to grain weight in multiple environments based on inclusive composite interval mapping method. The analysis of variance of major effect QTLs were performed to judge the additive interaction effect among different QTLs, and to analyse its effect on traits related to grain weight. At the same time, the corresponding kompetitive allele specific PCR marker was developed according to the closely linked SNP loci of major QTL for grain length, and verified in 242 wheat accessions worldwide.【Result】In this study, a high density genetic map of Heshangtou/Longchun 23 RIL population was constructed, with full length 4 543 cM, including 22 linkage groups, covering 21 chromosomes of wheat, and the average genetic distance was 1.7 cM. There was a significant correlation between genetic map and physical map, and the Pearson correlation coefficient were 0.77-0.99 (P<0.001). A total of 51 QTLs related to grain weight were detected, among them, 4 stable major QTLs were found in multi-environments (three or more environments) and distributed on 2D, 5A, 6B and 7D chromosomes. According to the physical interval and functional markers, it is inferred that stable major QTLs Qtkw.nwafu-2D.1 and Qtkw.nwafu-7D are photoperiod gene Ppd-D1 and flowering gene FT-D1, respectively. The analysis of variance shows that there is a significant interaction between them. The favorite alleles polymerization of Qtkw.nwafu-2D.1 and Qtkw.nwafu-7D can significantly increase thousand grain weight and grain width of wheat. In addition, the corresponding KASP molecular detection marker AX-111067709 was developed based on the co-segregated SNP of the major locus Qgl.nwafu-5A for grain length, which was significantly correlated with grain length and grain weight traits in a diversity panel comprising of 242 wheat accessions, and could increase grain length by 3.33% to 4.59% and grain weight 5.70% to 10.35% in different environments (P<0.001).【Conclusion】There are several genetic loci that affect traits linked to grain weight in Heshangtou (HST) and Longchun 23 (LC23), and Qtkw.nwafu-2D.1 and Qtkw.nwafu-7D dramatically increased thousand grain weight and grain width through additive interaction effects. Qgl.nwafu-5A is significantly correlated with grain weight and grain length, and its co-segregated molecular marker AX-11106770 can be used in molecular marker assisted selection breeding.

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    Genome-Wide Association Analysis of Yield Traits in Xinjiang Winter Wheat Germplasm
    MA YanMing, LOU HongYao, ZHANG ShengJun, WANG Wei, GUO Ying, NI ZhongFu, LIU Jie
    Scientia Agricultura Sinica    2023, 56 (18): 3487-3499.   DOI: 10.3864/j.issn.0578-1752.2023.18.001
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    Objective】To discover new high yield genes in wheat by association analysis, which can provide technical supports for the innovation and genetic improvement of high yield germplasm resources in wheat.【Method】Totally 188 bread wheat cultivars in Xinjiang were genotyped using the wheat 55K genotyping assay. GWAS was carried out to identify the signifcant single nucleotide polymorphisms (SNPs) which were associated with 9 wheat yield traits in 6 environments. The MLM algorithm in TASSEL5.0 was used to analyze the nine traits related to wheat yield traits.【Result】Totally 1309 SNPs explained 7.259%-70.792% of the phenotypic variation. 38 SNP loci were identifed, which were significantly correlated with 5 plant height weight SNP loci, 10 spike length weight SNP loci, 10 spikelet number SNP loci, 6 fertile spikelet number SNP loci, 6 spike grain number SNP loci, and 1 thousand grain weight SNP loci. These loci can explain 9.10%-23.81% of phenotypic variations. Comparing these 38 loci with the published wheat genome loci, only 3 functional genes were found, which annotated with gene function. There genes are: TraesCS2A01G448800 on chromosome 2A, which is close to the plant height associated site AX-108794050 and is related to the metabolic synthesis of transcription factor bHLH71; TraesCS2A01G448800, located on chromosome 1A at a distance similar to the spike length associated site AX-110689765, is related to protein coding; TraesCS4B01G031100, located on the 4B chromosome at a distance similar to the 1000 grain weight associated site AX-110399975, is associated with the encoding serine/threonine protein kinase SD1-8 and is involved in regulating cell proliferation and differentiation. 【Conclusion】38 QTL loci associated with wheat yield traits were detected. After verification, it was found that the associated excellent alleles have the effect of reducing plant height, increasing spike length, spikelet number, fertile spikelet number, grain number per spike, and thousand grain weight.

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    Effects of Long-Term Straw Return and Nitrogen Application Rate on Organic Carbon Storage, Components and Aggregates in Cultivated Layers
    GUO RongBo, LI GuoDong, PAN MengYu, ZHENG XianFeng, WANG ZhaoHui, HE Gang
    Scientia Agricultura Sinica    2023, 56 (20): 4035-4048.   DOI: 10.3864/j.issn.0578-1752.2023.20.009
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    【Objective】The results of carbon sequestration studies on combining straw returning with nitrogen fertilizer are controversial. Aimed at such problem, this experiment was carried out to reveal the effects of combining straw returning with nitrogen fertilizer on Carbon sequestration capacity and mechanism of farmland, so as to provide a reference for the future research. 【Method】Based on 11 years of long-term positioning experiments, this paper adopted split-zone design, the main treatment included straw returning to soil and removal straw from field, and the subplots included three N application rate, which were no nitrogen (N0), 168 kg·hm-2 (N168, nitrogen), and 336 kg·hm-2 (N336, excessive nitrogen application). 【Result】Compared with wheat without nitrogen fertilizer, wheat yield increased by 14.4%-19.5% with nitrogen fertilizer. The effect of straw returning to the field on yield was not significant. Straw returning significantly increased the cumulative input of soil carbon by 70.8% (P<0.05), but had no significant effect on soil organic carbon storage. Compared N0, the nitrogen application significantly increased soil carbon accumulation input and soil organic carbon storage by 7.7%-8.5% (P<0.05) and 4.7%-8.1% (P<0.05), respectively. The application of nitrogen fertilizer significantly increased the carbon fixation rate by 32.7%-56.1% (P<0.05), and N336 significantly increased the soil carbon fixation efficiency by 51.8% (P<0.05); straw returning to the field did not significantly improve the soil carbon fixation rate, but significantly reduced the carbon fixation efficiency by 30.9% (P<0.05). Both nitrogen application and straw returning could improve soil carbon pool capacity, and N0 and N168 have reached carbon saturation. The content of soluble organic carbon (DOC), microbial biomass carbon (MBC) and easily oxidized organic carbon (EO) in the soil increased by 4.6%, 11.2% and 4.5% respectively after returning straw to the field. Compared N0, DOC under N168 and N336 increased by 14.12% and 29.54% respectively; MBC decreased by 14.0% and 28.0% on average, respectively; EO increased by 8.2% and 11.5%, respectively. Straw returning to the field was beneficial to the improvement of soil DOC/SOC and microbial entropy. Applying nitrogen fertilizer was beneficial to the increase of DOC/SOC, but reduced the microbial entropy. Both straw returning and nitrogen fertilizer application had no effect on soil EO/SOC. Both straw returning and nitrogen application were beneficial to the improvement of macroaggregates (>0.25 mm), and straw returning significantly increased the organic carbon content of macroaggregates by 5.2%. The average weight diameter (MWD) and geometric average diameter (GMD) of aggregates under non-return showed a trend of first increasing and then decreasing with the increase of nitrogen level, while under straw returning, it showed an increase with the increase of nitrogen level. Straw returning increased the MWD and GMD of aggregates by 8.8% and 7.5% respectively, and the application of nitrogen fertilizer increased the MWD and GMD by 14.1%-22.7% and 16.8%-23.4% respectively, compared with CK. Both straw returning and nitrogen application could improve the distribution of organic carbon in large aggregates. 【Conclusion】Straw returning with nitrogen fertilizer could increase carbon input, increase activated organic carbon content, reduce microbial activity, and improve the protection of organic carbon by aggregates.

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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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    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
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    【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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    Effects of Long-Term Synergistic Application of Organic Materials and Chemical Fertilizers on Bacterial Community and Enzyme Activity in Wheat-Maize Rotation Fluvo-Aquic Soil
    ZHANG LingFei, MA Lei, LI YuDong, ZHENG FuLi, WEI JianLin, TAN DeShui, CUI XiuMin, LI Yan
    Scientia Agricultura Sinica    2023, 56 (19): 3843-3855.   DOI: 10.3864/j.issn.0578-1752.2023.19.011
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    【Objective】This experiment studied the effects of long-term synergistic application of organic materials and chemical fertilizers on soil bacterial community and enzyme activity, and revealed the relationship between soil nutrients, extracellular enzyme activity and bacterial community, so as to provide a theoretical basis for formulating long-term and reasonable fertilization strategies under wheat-maize rotation system in fluvo-aquic soil. 【Method】 Based on a 10-year located experiment, five treatments were set up, including no fertilization (NF), chemical fertilizer (NPK), chemical fertilizer with straw return (NPKS), 50% chemical fertilizer with 6 000 kg·hm-2 pig manure (NPKP), and 50% chemical fertilizer with 6 000 kg·hm-2 cow manure ( NPKC ). 【Result】 (1) The combined application of organic materials and chemical fertilizers ( NPKS, NPKP and NPKC ) could significantly improve soil fertility and extracellular enzyme activity, among which NPKC treatment had the most significant effect. Compared with NPK treatment, the contents of organic matter, total nitrogen, available nitrogen, available phosphorus and alkaline phosphatase activity were increased by 13.8%-15.4%, 9.7%-15.5%, 7.2%-15.9%, 13.6%-38.5%和2.5%-13.1%. (2) Long-term combined application of organic and inorganic fertilizer significantly changed the bacterial community structure and composition. In the wheat season, compared with NPK treatment, NPKS treatment significantly increased the abundance of Aggregatilinea and Parachlamydia, NPKP treatment significantly increased the abundance of Pseudomonas, Nonomuraea and Flexilinea, while NPKC treatment only significantly increased the abundance of Luteitalea. In the maize season, compared with NPK treatment, NPKS treatment significantly increased the abundance of Phycisphaera and Syntrophothermus, NPKP treatment significantly increased the abundance of Gemmatimonas, and NPKC treatment significantly increased the abundance of Aquipuribacter and Desulfosoma. (3) The results of functional prediction showed that combined application of organic and inorganic fertilizers could promote soil carbon and nitrogen cycling compared with long-term single application of chemical fertilizer. In particular, the NPKC treatment had a strong effect on nitrification, ureolysis, aromatic compound degradation, xylanolysis and cellulolysis. (4) Mental analysis showed that soil pH was the main factor regulating bacterial community structure and ecological function in fluvo-aquic soil. 【Conclusion】 Long-term application of organic and inorganic fertilizers (especially chemical fertilizers combined with cow manure) could improve soil fertility and extracellular enzyme activity, increase the abundance of beneficial bacteria, significantly change the structure and composition of bacterial communities, and promote the circulation of carbon, nitrogen and phosphorus, thus construct an environment suitable for crop and bacterial growth in fluvo-aquic soil.

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    QTL Identification and Genetic Analysis of Plant Height in Wheat Based on 16K SNP Array
    YAO QiFu, CHEN HuangXin, ZHOU JieGuang, MA RuiYing, DENG Liang, TAN ChenXinYu, SONG JingHan, LÜ JiJuan, MA Jian
    Scientia Agricultura Sinica    2023, 56 (12): 2237-2248.   DOI: 10.3864/j.issn.0578-1752.2023.12.001
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    【Objective】There is a close relationship between plant height (PH) and yield. The aim of this study is to further explore quantitative trait loci (QTL) of PH with breeding value in wheat and analyze the genetic effects of major QTL for PH on other yield related traits toward to providing a theoretical basis for molecular breeding. 【Method】A recombinant inbred line population (MC) derived from a cross between the natural mutant msf and Chuannong 16 (CN16) was used for QTL analysis. During 2020 to 2022, planting and PH phenotype identification were conducted at five environments in Wenjiang, Chongzhou, and Ya’an of Sichuan Province. The high-quality genetic linkage map constructed using the 16K SNP array was used for QTL mapping of PH. Genotypes of flanking markers of major QTL for PH were used to analyze the genetic effects of positive alleles on yield related traits and evaluate the potentiality of QTL for yield improvement. 【Result】Eight QTL controlling PH were identified on chromosomes 1A, 3D, 4D, 5A, and 7B, respectively. Among them, two stable and major QTL, QPh.sau-MC-1A and QPh.sau-MC-5A, were located, which explained 9.09% to 25.56% and 3.91% to 13.09% of the phenotypic variation rate, respectively. Their positive alleles were all from CN16. The additive effect analysis showed that PH of the lines carrying positive alleles from QPh.sau-MC-1A and QPh.sau-MC-5A was significantly higher than that of the lines carrying only a single positive allele or none. Correlation analysis showed that PH has a significantly positive correlation with effective tiller number (ETN), a significantly negative correlation with flag leaf width (FLW), and no significant correlation with kernel number per spike (KNPS), kernel weight per spike (KWPS), thousand kernel weight (TKW), flag leaf length (FLL) and anthesis date (AD). Genetic effects analysis showed that positive allele of QPh.sau-MC-1A had a significant effect on improving ETN (56.51%), a significant effect on decreasing KNPS (-11.26%), KWPS (-13.04%), TKW (-5.47%), and FLW (-2.85%), and a significant effect on advancing AD (-0.61%). Positive allele of QPh.sau-MC-5A had a significant effect on improving ETN (10.57%), KNPS (4.32%), and TKW (2.92%), and a significant effect on delaying AD (1.07%). 【Conclusion】A major QTL QPh.sau-MC-5A for PH was mapped on chromosome 5A, and its positive allele significantly increased ETN, KNPS, and TKW, indicating that it may have a positive impact on yield.

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    The Effect of indica/Xian Pedigree Introgression in japonica/Geng Rice Breeding in China
    XU HAI, LI XIUKUN, LU JIAHAO, JIANG KAI, MA YUE, XU ZHENGJIN, XU QUAN
    Scientia Agricultura Sinica    2023, 56 (22): 4359-4370.   DOI: 10.3864/j.issn.0578-1752.2023.22.001
    Abstract381)   HTML64)    PDF (4344KB)(319)       Save

    【Objective】To demonstrate the impact of indica/Xian (XI) pedigree introgression on the yield and quality of japonica/Geng (GJ) rice varieties, providing a theoretical basis and genomic resources for optimizing XI pedigree introgression breeding programs in northern GJ rice.【Method】In this study, the whole genome sequence on Illumina platform was employed to elucidate the effects of XI pedigree introgression on the yield and quality of rice in Northeast China were analyzed using recombinant inbred lines (RIL) derived from the cross between XI and GJ varieties, and 74 major GJ varieties grown from Heilongjiang, Liaoning, Shandong, and Jiangsu provinces as test materials. Using CRISPR/Cas9 gene editing technology to knock out the unfavorable genes introduced by XI pedigree introgression. 【Result】Analysis of RIL revealed a significant positive correlation between XI pedigree introgression and panicle length, grain length, and a negative correlation with head rice ratio. XI pedigree introgression was significantly negatively correlated with Amylose content, and significantly positively correlated with protein content in Jiangsu. With the increase of latitude, the correlation efficiency between XI pedigree introgression and grain shape increased, while the correlation between XI pedigree introgression and panicle length and head rice ratio decreased. The genomic fragments of XI pedigree introgression are unevenly distributed across different chromosomes and are more abundantly present on chromosomes 1, 10, 11, and 12. The XI pedigree introgression of the major cultivars in Jiangsu and Liaoning provinces is significantly higher than that in Heilongjiang and Shandong provinces, and the XI pedigree introgression of the cultivars after 2000 is significantly higher than that before 2000. The XI pedigree introgression includes multiple resistance and fertility-related genes. The project identified an XI pedigree introgression fragment on chromosome 5 of YF47, including the XI type grain regulatory gene GS5 and XI type chalkiness regulatory gene Chalk5, which increased the 1000 grain weight of YF47 but affected its chalkiness-related traits. The project uses CRISPR/Cas9 technology to knock out the Chalk5 gene of YF47. The grain shape of the homozygous gene editing plants is similar to those of YF47, and its chalkiness character has been significantly improved. 【Conclusion】The XI pedigree introgression mainly increases the yield potential of GJ rice by increasing the number of grains per panicle, but has a negative impact on milling quality. Exploring the unfavorable alleles in varieties through high-throughput genome sequencing, combined with CRISPR/Cas9 gene editing, to break the genetic drag in breeding using the cross between XI and GJ, is an efficient breeding strategy that can quickly and accurately improve target traits.

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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
    Abstract360)   HTML63)    PDF (644KB)(556)       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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    Research Progress of PPR Protein in Plant Abiotic Stress Response
    LI Cheng, LU Kai, WANG CaiLin, ZHANG YaDong
    Scientia Agricultura Sinica    2023, 56 (24): 4801-4813.   DOI: 10.3864/j.issn.0578-1752.2023.24.001
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    Abiotic stress is one of the main factors causing global grain yield reduction. It is of great significance to study the function and response mechanisms of plant stress-related proteins to improve crop stress resistance. Pentatricopeptide repeat (PPR) proteins, belong to the largest family of nuclear coding proteins in higher plants and are named because they contain highly specific PPR motifs. Depending on motif type and arrangement, PPR proteins can be classified as P and PLS, and PLS proteins can be further classified as PLS, E, E+, DYW, and other subclasses based on their carboxyl-terminal domains. PPR proteins are widely distributed in terrestrial plants, mainly in chloroplasts and mitochondria, and a few in the nucleus. As sequence-specific RNA binding proteins, PPR proteins are involved in multiple aspects of plant RNA processing, including RNA editing, splicing, stabilization, and translation. PPR protein plays a variety of important roles in the whole life process of plants, but the mechanism of its action in plant stress resistance is not well understood. Based on the localization and function of PPR proteins related to abiotic stress reported, the mechanism of PPR proteins involved in regulation of abiotic stress, including post-transcriptional regulation and retrograde signaling, was reviewed and discussed in this paper. Post-transcriptional regulation is related to the role of PPR proteins in the modification of RNA after transcription. It is generally believed that PPR affects stress resistance in plants by regulating the expression of stress-related genes via binding RNA and by regulating the metabolism of organelle RNA. In terms of retrograde signaling, damage to PPR proteins can lead to impaired mitochondrial or chloroplast function, and then produce various retrograde signals (such as ROS), thereby regulating the expression of related genes and resisting adversity. However, since plastid signaling is affected by many environmental factors, some of which are still unclear, the mechanism of the PPR protein in retrograde signaling remains to be clarified. In addition, PPR proteins are pleiotropic and some have important effects on plant growth and reproduction while acting on stress resistance. Finally, this paper further analyzed the current research status of PPR protein as an RNA editing tool, discussed the remaining problems and research prospects of PPR protein in the direction of abiotic stress, and pointed out the key points and difficulties that need to be paid attention to in future research, to provide references for further research on PPR protein and crop abiotic stress resistance 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
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    【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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    Seedling Characterization and Genetic Analysis of Low Phosphorus Tolerance in Shanxi Varieties
    WEI NaiCui, TAO JinBo, YUAN MingYang, ZHANG Yu, KAI MengXiang, QIAO Ling, WU BangBang, HAO YuQiong, ZHENG XingWei, WANG JuanLing, ZHAO JiaJia, ZHENG Jun
    Scientia Agricultura Sinica    2024, 57 (5): 831-845.   DOI: 10.3864/j.issn.0578-1752.2024.05.001
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    【Objective】In arid and semi-arid regions, the water and nutrients are scarce in the soil. The phosphorus use efficiency between different wheat genotypes varies greatly. Therefore, identification of low phosphorus-tolerant germplasm and mapping of related loci is helpful for genetic improvement of wheat. 【Method】Using 282 Shanxi wheat varieties as materials, twelve seedling morphological indicators were investigated under three phosphorus concentrations, including SDW, RDW, DW, SFW, RFW, FW, MRL, TRL, RS, RV, RD, and RN. Principal component analysis, membership function analysis, and cluster analysis were used to comprehensively evaluate the low phosphorus tolerance characteristics of different varieties at the seedling stage. On this basis, the trait evolution trend and biomass allocation at seedling stage were analyzed. At the same time, GWAS was used to identify significant loci related to the low phosphorus-related traits. 【Result】The response of different traits to low phosphorus at the seedling stage was different. Lower phosphorus concentrations led to changes in biomass allocation strategy, and shoot growth was less affected by change in phosphorus concentrations than root growth. The decrease in phosphorus concentration inhibited the growth of shoot, and SDW and SFW were significantly reduced. In contrast, low phosphorus promoted root growth, and the indicators of RDW, RFW, MRL, TRL, RV and RN increased significantly. According to the correlation analysis between D-value and morphological indicators, it was found that MRL and RD could be used as selection indicators for low phosphorus tolerance at seedling stage. Based on D-value clustering analysis, 9 low phosphorus tolerant varieties were selected, including Jinmai 46, Jinmai 61, Youmangdahongjing, Hongtumai, Hongheshang, Baikehong, Baixianmai, Huoshaotou, Baishanmai. Analysing trends in trait evolution showed that cultivars were not directly selected for their ability to tolerate low phosphorus. The ability to tolerate low phosphorus decreased first and then increased over time. Before 2010, there was a decreasing trend in the ability of varieties to tolerate low phosphorus, and after 2010, there was an increase in the ability of varieties to tolerate low phosphorus. GWAS stably detected eight loci with R2>10% in three environments, in which 1A_545074550, 2B_489279799, 6A_166899658 and 6A_273060644 were not reported previously.【Conclusion】The MRL and RD can be used as selection indicators for low phosphorus tolerance at seedling stage. A total of nine varieties were selected through comprehensive evaluation of ability in Shanxi wheat to tolerate low phosphorus during seedling stage. Association analysis detected four novel loci associated with low phosphorus tolerance on chromosomes 1A, 2B and 6A, and the results provide germplasm resources and QTL for future low phosphorus tolerance wheat breeding.

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    Cloning and Functional Characterization of the Promoter of GhSLD1 Gene That Predominantly Expressed in Cotton Fiber
    LIU Fang, XU MengBei, WANG QiaoLing, MENG Qian, LI GuiMing, ZHANG HongJu, TIAN HuiDan, XU Fan, LUO Ming
    Scientia Agricultura Sinica    2023, 56 (19): 3712-3722.   DOI: 10.3864/j.issn.0578-1752.2023.19.002
    Abstract326)   HTML34)    PDF (2559KB)(318)       Save

    【Objective】Cotton fiber is the main economic product of cotton. It is the epidermal cells of the ovule outer integument through polar elongation and secondary wall thickening. As one of the longest plant cells, the cotton fiber cells are regarded as an ideal material in the study of plant cell growth and development. Identification of promoters specifically or preferentially expressed in fiber cells is of great significance for basic research on fiber development and molecular breeding for improving fiber traits. 【Method】In this study, we cloned the promoter of GhSLD1 gene, which is predominantly expressed in fiber cells. Through the PlantCARE website for promoter sequence analysis, we identified the important cis-regulatory elements contained in the cloned sequence. According to the distribution of some important cis-regulatory elements, the cloned promoter fragments were deleted at 5′- end. A total of 4 promoter fragments were obtained and the corresponding plant expression vector was constructed. The constructed plant expression vectors were used for genetic transformation of tobacco and cotton. The transgenic plants were identified through molecular identification of transgenic tobacco and cotton. GUS activity in different tissues, organs and fiber cells of transgenic plants at different development stages was also investigated. 【Result】The longest promoter cloned was 2 900 bp in length. In addition to a lot of transcription regulatory elements in the promoter, the sequence also contained multiple abscisic acid response elements, the elements essential for the anaerobic induction, methyl jasmonate response elements, brassinolide response elements, the elements involved in seed-specific regulation, the elements involved in defense and stress responsiveness, and MYB transcription factor binding sites. Four promoter fragments with a length of 2 900 bp (GhSLD-P1), 2 178 bp (GhSLD1-P2), 1 657 bp (GhSLD1-P3) and 1 232 bp (GhSLD-P4) were obtained by the 5′-terminal deletion, respectively. The transgenic tobacco plants were generated after confirmed by molecular identification. GhSLD-P1, GhSLD1-P2 and GhSLD1-P3 did not express in transgenic tobacco, while GhSLD-P4 is widely expressed, and the expression level of GhSLD-P4 was similar to that of CaMV 35S promoter. The different sequence between GhSLD1-P3 and GhSLD-P4 contained four abscisic acid response elements, two brassinolide response elements, and three MYB binding sites. These cis-regulatory elements may be associated with the non-expression of GhSLD1-P1, GhSLD1-P2, and GhSLD1-P3 promoters in transgenic tobacco. The transgenic cotton plants of GhSLD1-P2 were obtained after confirmed by molecular identification. GhSLD1-P2 predominantly expressed in transgenic cotton fibers, and its expression level was higher at the elongation stage (10-15 DPA) of fiber cells while lower in the early developmental stage (5 DPA) of fiber cells and the stage of secondary cell wall deposition (20-30 DPA). 【Conclusion】The GhSLD1-P4 promoter was a widely expressed promoter, and the GhSLD1-P2 promoter was a fiber predominant expression promoter, which was highly expressed during the elongation of fibers. It could be applied to the study on the gene function involved in cotton fiber development and molecular breeding for improving fiber traits.

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    The Construction and Application of SSR and SNP Molecular ID for Maize Germplasm Resources of Jilin Province
    ZHANG MingQi, WANG Rui, ZHANG ChunXiao, SUN Bo, REN Jie, LI ShuFang, WANG Lu, ZHU ShaoXi, ZHANG JiangBin, SHI XinChen, WANG HaiJie, ZHANG YunLong, TIAN HongLi, ZHAO YiKun, KUANG Meng, WANG YuanDong, YI HongMei, LI XiaoHui, WANG FengGe
    Scientia Agricultura Sinica    2024, 57 (2): 236-249.   DOI: 10.3864/j.issn.0578-1752.2024.02.002
    Abstract323)   HTML36)    PDF (9255KB)(251)       Save

    【Objective】 Crop germplasm resources hold a crucial strategic position. The Maize Germplasm Resources Bank in Jilin Province safeguards a collection of germplasm resources distinctively representative of the Northern Spring Maize Region. Traditional germplasm resource management faces challenges in ascertaining accurate identity information. To address this issue, molecular marker technology has been employed to establish a process for the construction and classification of molecular IDs for germplasm resources, thereby enabling precise identification and bolstering categorical management. Thorough exploration of the exceptional resources within Jilin Province's Maize Germplasm Resources Bank is intended to advance the shared utilization of these valuable germplasm resources. 【Method】 A total of 2 918 maize germplasm resources were utilized from the Jilin Provincial Maize Germplasm Resources Bank as subjects of the study, the molecular IDs were constructed by using 40 pairs of SSR markers and 61 214 SNP markers recommended in maize variety identification standards. Based on the molecular ID information, the germplasm resources were categorized into core, closely related, heterogeneous, and population groups for management purposes. Furthermore, the core germplasms were analyzed on genetic diversity. 【Result】 In this investigation, the SSR molecular IDs were constructed for 2 918 maize germplasm resources, while the SNP molecular IDs were constructed for 2 502 maize germplasm resources, excluding heterogeneous germplasm. The standards for the construction of SSR and SNP molecular IDs were established for maize germplasm resources. The SSR molecular ID is composed of a combination of three-digit numbers and one-letter code converted from 40 SSR loci fingerprints, stored in the form of a QR code. The SNP molecular ID converts the fingerprints of 61 214 SNP loci into visual barcodes. Based on the features of sample homozygosity and fingerprint specificity, the samples were categorized into 1 561 cores, 705 closely related, 416 heterogeneous, and 236 population types of germplasm resources. Genetic diversity analysis indicates that domestic germplasm resources, represented by Lüdahonggu and Huanggai groups, constituting the main germplasm resources in the Jilin Provincial Maize Germplasm Resources Bank, accounting for 64.38% of all core germplasm resources. 【Conclusion】 This research outlines a methodology for constructing molecular IDs for maize germplasm resources. The SSR molecular IDs were constructed for 2 918 accessions stored in the Jilin Provincial Maize Germplasm Resources Bank and the SNP molecular IDs were constructed for 2 502 among them. The germplasm resources were categorized into core, closely related, heterogeneous, and population types to achieve the classification management.

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    CRISPR/Cas9-Mediated Editing of MODD Enhances Rice Dormancy
    GUO NaiHui, ZHANG WenZhong, SHENG ZhongHua, HU PeiSong
    Scientia Agricultura Sinica    2024, 57 (2): 227-235.   DOI: 10.3864/j.issn.0578-1752.2024.02.001
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    【Objective】 Dormancy is an important agronomic trait of rice. Proper dormancy can inhibit the preharvest sprouting of rice and is a key factor to ensure yield and quality. However, the genes and regulatory networks of rice dormancy regulation still need further study. The MODD encoded a protein with unknown function, and it negatively regulate rice abscisic acid signaling and drought resistance, but its function in regulating rice dormancy is unknown. Studying the function of MODD in regulating rice dormancy will help to improve the rice dormancy regulatory network, and at the same time provide a new theoretical basis and germplasm resources for genetic breeding of preharvest sprouting resistance.【Method】 Based on the gene sequences published in the RGAP database, a CRISPR-Cas9 knockout vector for MODD was constructed, and the calli of Zhonghua 11 was transformed through agrobacterium mediated genetic transformation to obtain transgenic rice plants. The MODD knockout homozygous lines were screened and identified using PCR amplification, sequencing technology, and qRT-PCR technology. The amino acid sequences of the two mutant lines (KO-1 and KO-2) were obtained according to the CDS of the two mutant lines, and then the protein sequences of ZH11 and the two mutant lines (KO-1 and KO-2) were compared by DNAMAN. The homologous genes of MODD in rice were screened using Linux system. Take the seeds 35 days after heading and investigated the germination rate of ZH11 and knockout lines. The yeast hybridization and LUC experiments were used to verify the upstream gene of MODD. 【Result】 Six MODD homologous genes were found in rice, which were LOC_Os07g41160, LOC_Os03g30570, LOC_Os03g53630, LOC_Os04g35430, LOC_Os03g17050, LOC_Os06g01170. The knockout vector was successfully constructed and transferred it into ZH11, two homozygous mutant lines (KO-1 and KO-2) were obtained. The qRT-PCR results showed that the expression level of MODD in the two mutant line (KO-1 and KO-2) was significantly reduced. Protein sequence analysis showed that the frameshift mutations of KO-1 and KO-2 caused the early termination of protein translation. The germination rate of the two mutant lines (KO-1 and KO-2) was significantly lower than that of ZH11 by 15% and 15% respectively on the third day after water absorption; After that, the difference gradually expanded and reached the maximum on the 6th day, which was significantly lower than that of ZH11 by 35% and 35% respectively. The preharvest sprouting of two mutant lines (KO-1 and KO-2) was significantly lower than that of ZH11. The results of Y1H experiment showed that ABI5 could bind to the promoter region of MODD in yeast, and the binding range was further reduced to less than 300bp. LUC results showed that the fluorescence value of ABI5 was 2.6 times that of none alone, indicating that ABI5 could activate the expression of MODD.【Conclusion】 Knocking out MODD could increase seed dormancy, and MODD may regulate seed dormancy through ABA signaling pathway.

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    Analysis and Comprehensive Evaluation of Phenotype Genetic Diversity in Kam Sweet Rice Germplasm Resources in Guizhou
    LI Huan, YAN XiaoQing, YANG ZhanLie, TAN JinYu, LI XiaoBing, CHEN NengGang, WU RongJu, CHEN HuiCha, RUAN RenChao
    Scientia Agricultura Sinica    2023, 56 (11): 2035-2046.   DOI: 10.3864/j.issn.0578-1752.2023.11.001
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    【Objective】To analyze the phenotypic genetic diversity of traditional characteristic landraces of Kam Sweet Rice (KSR) in Guizhou, this study screened the comprehensive evaluation indicators for phenotype, and constructed a reliable mathematical model for comprehensive evaluation on phenotypes. This study provides valuable theoretical support for the discovery and breeding of exceptional KSR germplasm resources. 【Method】13 phenotypic traits from a total of 286 KSR accessions collected from the Southeast Guizhou were measured. A variety of multiple statistical methods, including Shannon-Wiener genetic diversity index, principal component analysis, subordinate function value analysis, and stepwise regression analysis, were used to analyze the phenotypic genetic diversity and comprehensively evaluate on KSR germplasm resources. 【Result】Firstly, the KSR germplasm showed high phenotypic genetic diversity, with the variation coefficients of the 13 phenotypic traits ranging from 6.79% (Grain width) to 30.73% (Panicle number per plant), and the diversity index (H') ranging from 2.484 (Ratio of length to width for grain) to 2.996 (Flag leaf width). Correlation analysis showed significant or highly significant correlations among the different traits. Principal component analysis showed that the 13 traits were integrated into 7 principal components, with contribution rates ranging from 8.44% to 23.14%, and the additive contributing rate came up to 90.29%. The phenotypic comprehensive evaluation D value calculated by subordinate function values analysis showed that the top 5 varieties had the best characteristics, and 11 phenotypic traits were significantly correlated with the D value. The stepwise regression analysis established a mathematical model for phenotypic evaluation of KSR, Y=-0.249+0.119X5+0.395X13+0.071X6-0.161X3+0.108X10+0.170X2+0.110X9 (F=2800.200, R2=0.986). Based on the model, 7 comprehensive evaluation indicators were screened out. At last, the 286 germplasm resources were systematically clustered into four categories based on the D value, displaying significant differences among the groups and outstanding characteristics. The group I, including 38 accessions, showed the best comprehensive traits and high yield potential; the group Ⅱ, including 103 accessions, showed general comprehensive traits and high seed setting rate; the group Ⅲ, including 94 accessions, showed poor comprehensive traits and long growth period; the group Ⅳ, including 51 accessions, had the worst comprehensive traits. 【Conclusion】The KSR germplasm resources in Guizhou have abundant phenotypic genetic diversity. It is feasible to use multiple statistical analysis methods for comprehensive evaluation on KSR germplasm diversity. The regression equation constructed under the same conditions can quantitatively evaluate the comprehensive performance of KSR germplasm resources. The filled grains per panicle, grain width, seed setting rate, panicle number per plant, flag leaf length, plant height and grain yield per plant can be used for identifying KSR germplasm resources. The outstanding germplasm resources with coordinated comprehensive traits such as Zaohe, Nuohe-12, 90 Tianhe, Goudong-1 and Nuohe-11 were screened out, which can be ultilized for genetic improvement of KSR and for rice breeding.

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    Population Genetic Analysis of Puccinia striiformis tritici in Main Winter-Increasing Areas Based on Virulent Phenotypes and Genotypes
    GAO XinPei, ZHAO Jun, LIU BoFan, GUO Yi, KANG ZhenSheng, ZHAN GangMing
    Scientia Agricultura Sinica    2023, 56 (14): 2629-2642.   DOI: 10.3864/j.issn.0578-1752.2023.14.001
    Abstract307)   HTML37)    PDF (1592KB)(374)       Save

    【Objective】To clarify the virulence structure and genetic diversity of Pst populations in the major winter-increasing areas of China, and to provide reference for the prevention and control of Pst and the rational layout of wheat resistance genes in the winter-increasing areas and the wheat production in Huang-huai-hai. 【Method】A total of 148 Pst isolates were collected and isolated from the major winter-increasing areas such as Sichuan Basin, Hubei and southern Henan, and the virulence phenotype was identified by using Chinese differentials and single-gene lines, and 17 pairs of KASP-SNP primers were used to mark the isolates and complete the genotype analysis. 【Result】Based on the Chinese differentials, 14 known races and 63 unknown pathotypes were identified, among which CYR34 (16.2%), G22-14 (12.2%), CYR32 (6.8%), CYR33 (5.4%) were the dominant races (pathotypes); based on the single-gene lines, 113 races (pathotypes) were identified, among which race1 (7.4%), race2 (3.4%), race3 (3.4%) were the dominant races (pathotypes). The Guinong 22 group was the largest epidemic group of Pst population in China’s winter-increasing area, and all tested Pst isolates did not infect single-gene lines varieties carrying Yr5 and Yr15. The virulence phenotype and genotype of CYR34 and G22-14 showed diversification by single-gene lines virulence identification and molecular marker, indicating that there was high differentiation within these two dominant races. The clustering based on the virulence data of two sets of differentials showed that the Pst populations in Sichuan Basin and southern Hubei were similar, while the Pst populations in northwestern Hubei and southern Henan were similar; the genetic clustering based on KASP-SNP molecular data showed that there was genotype differentiation between the Pst populations in Sichuan Basin, southern Hubei and northwestern Hubei, southern Henan; Structure analysis showed that Sichuan Basin, southern Hubei population mainly had two genetic backgrounds, northwestern Hubei, southern Henan population mainly had one genetic background; population genetic differentiation analysis showed that Sichuan Basin Pst population and southern Henan Pst population had the largest Fst value, which was 0.118, with the largest genetic difference and obvious genetic differentiation; northwestern Hubei population and southern Henan population had the smallest degree of genetic differentiation, Fst value was 0.010; gene flow analysis obtained Nm value between northwestern Hubei population and southern Henan population was 25.236, Nm>4, there was a high-level gene flow between them, northwestern Hubei and southern Henan population and Sichuan Basin population had Nm values of 2.923 and 1.864 respectively, both had a low-level gene flow; genetic diversity analysis results showed that Sichuan Basin, southern Hubei region Pst population had a high-level of genetic diversity, northwestern Hubei, southern Henan Pst population had a low-level of genetic diversity. The above conclusions all support that Sichuan Basin, southern Hubei population has genetic differentiation with northwestern Hubei, southern Henan population. 【Conclusion】Single-gene lines can accurately identify Chinese Pst races; Pst populations in China’s major winter-increasing areas have different sources.

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    Effects of Changing Normal and Extreme Climate States on Maize Meteorological Yield in Northeast China
    ZHANG WenJing, ZHAO Jin, CUI WenQian, LI ManYao, LI E, GONG XiaoYa, YANG XiaoGuang
    Scientia Agricultura Sinica    2023, 56 (10): 1859-1870.   DOI: 10.3864/j.issn.0578-1752.2023.10.004
    Abstract300)   HTML39)    PDF (2016KB)(220)       Save

    【Objective】Northeast China is the main grain production base in China, which has been significantly affected by climate change in recent years. It was of great significance to understand the impact of normal and extreme climate states changes on crop yield in Northeast China for regional crop production and national food security.【Method】In this study, the maize in Northeast China was used as research object, and the main climate factors affecting maize yield were screened to analyze the effects of normal and extreme climate states changes on maize yield in 81 counties in Northeast China from 1980 to 2018.【Result】(1) The average temperature, growing degree-days (GDD), and heat degree-days (HDD) during the maize growth period showed an increasing trend, and the rising rates were 0.34 ℃·(10 a)-1, 47.07 ℃·d·(10 a)-1, and 5.15 ℃·d·(10 a)-1, respectively. The precipitation showed a decreasing trend, with the rate of 7.0 mm·(10 a)-1; the average temperature, GDD, and HDD increased from northeast to southwest, while the precipitation increased from northwest to southeast. (2) The meteorological yield of maize in Northeast China showed an increasing trend from 1980 to 1999, with a rate of 80.93 kg·hm-2·a-1, while it showed a decreasing trend of 46.25 kg·hm-2·a-1 from 2000 to 2018. In terms of spatial distribution, it showed an increasing trend from the middle to the surrounding areas. The area with high yield was concentrated in the eastern part of Heilongjiang. The change of Liaoning was the most stable, and the fluctuation range was stable in the middle area. (3) By the multiple linear regression model, HDD contributed the most to meteorological yield from 1980 to 2018, and the effect was negative, which meant extreme high temperature had the greatest impact on maize yield in Northeast China and caused maize yield reduction; GDD had a positive effect, that is, the average temperature increased maize yield, and the greater GDD, the more yield increased; the precipitation had a negative effect; the interaction between temperature and precipitation had a positive impact on maize yield in Northeast China.【Conclusion】Normal and extreme climate states changes and its impact on maize meteorological yield in Northeast China from 1980 to 2018 were as follow: the normal and extreme temperature showed an overall increasing trend, while the normal precipitation showed a decreasing trend. Extreme high temperatures and normal precipitation led to a decrease in maize yield, but the average temperature increased maize yield, and the extreme high temperature had the greatest impact. In the future, it was necessary to make full use of the average temperature state and minimize the harm caused by extreme high temperature to ensure a high-stable maize production.

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    Development and Application of Specific Molecular Markers for Six Homologous Rice Blast Resistance Genes in Pi9 Locus of Rice
    YANG Hao, HUANG YanYan, YI ChunLin, SHI Jun, TAN ChuTian, REN WenRui, WANG WenMing
    Scientia Agricultura Sinica    2023, 56 (21): 4219-4233.   DOI: 10.3864/j.issn.0578-1752.2023.21.007
    Abstract291)   HTML26)    PDF (4029KB)(237)       Save

    【Objective】The Pi9 resistance gene locus, conferring a broad-spectrum resistance against Magnaporthe oryzae, is consist by several tandem homologous genes. Over 10 resistance genes have been cloned from this gene locus. This study aims to clarify the R gene composition at Pi9 locus in rice resource materials and promote the application of those genes in rice resistance breeding.【Method】Comparing the DNA sequence of cloned R genes at Pi9 locus, the specific nucleotide polymorphism sites were screened as the candidate sites. Subsequently, each R gene was blasted with 155 rice genomes in the database of Rice Resource Center. The most specific nucleotide polymorphism sites were picked out from the candidate site in each gene to develop primer pair of molecular markers. The PCR product of primer pairs was used to mark indicated R gene in tested rice materials via parameter optimization. To verify the results, the R genes were cloned from indicated rice variety randomly and examined by Sanger sequencing, or analyzed the R genes from the genome database if the genome sequence of indicated rice variety exists in Rice Resource Center. The R genes in Pi9 locus have high homology, which cause same specific nucleotide polymorphism sites existing in different R genes. Therefore, some R genes are hardly identified by one molecular marker. For this case, several molecular markers were employed to identify the indicated R gene simultaneously. Moreover, some specific nucleotide polymorphism sites are single nucleotide polymorphism (SNP), in where the primers of molecular markers have a mismatched base. In order to improve the specificity of PCR amplification, the adjacent base of SNP was mutated to generate two mismatched bases at 3′ site of primer.【Result】Finally, the valid molecular markers were developed for each R gene and identified 32.09% tested materials containing R genes at Pi9 locus. Pi9, Pid4, PigmR, Piz-t, Pi2 and Pi9-type5 are present in 1, 7, 8, 14, 23 and 33 tested materials, respectively. The Pi9 only presents in monogenic line but not in rice parent lines. The other genes are usually present in two or more gene combinations in rice parent lines. The Pi9-type5 often presents in pair with Pi2 and Piz-t, and presents alone in three rice parents, Chenghui 993, HR2168 and Mianhui 365. Yuhui 38 contains the most R genes at Pi9 locus, including Pi2, Pi9-type5, PigmR and Pid4. Chuangu B, Chuannong 4B, Neixiang 6B and Shuang 1B contain Piz-t, PigmR and Pid4. Qianxiang 654B contains Piz-t and Pid4.【Conclusion】This study successfully developed specific molecular markers for six homologous rice blast resistance genes in Pi9 locus and identified the R gene composition in Pi9 locus for 110 rice parent lines that used in rice breeding in Sichuan basin. It also discovered different types of R genes combination at Pi9 locus and provided a clear reference for choosing the resistance source in rice breeding.

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    Origin, Present Situation and Development Trend of Green Fertilizer
    WU ZhiJie, ZHANG LiLi, SHI YuanLiang, WEI ZhanBo, LI DongPo, GONG Ping, LI Jie, ZHANG Lei, WANG LingLi, WU KaiKuo, XUE Yan, SONG YuChao, CUI Lei
    Scientia Agricultura Sinica    2023, 56 (13): 2530-2546.   DOI: 10.3864/j.issn.0578-1752.2023.13.008
    Abstract283)   HTML23)    PDF (558KB)(527)       Save

    The new development concept of "innovation, coordination, green, openness and sharing" is the centralized reflection of China's development concept, direction and focus in the 14th Five-Year Plan and even in the longer term. The green development of agriculture is an important part of the implementation of the new development concept, which plays an important role in forming a harmonious coexistence between human beings and nature, ensuring food safety and creating a livable environment. Fertilizer, as the largest exogenous input and production material, plays a significant role and has a profound impact on the quantity and quality of agricultural products and the agricultural ecological environment, and plays a pivotal role in the green development of agriculture. However, the improper application of traditional fertilizers has caused the degradation of soil quality, environmental pollution and degradation of agricultural products, which urgently requires the transformation and upgrading of fertilizer products, and the development of green inputs has come into being. Green fertilizer concept and definition is: the application of quality and safety of raw materials, low-carbon environmental protection process, the use of physical - chemical - biological modification and efficiency technology production and use, with efficient and balanced nutrients, emission reduction and environmental protection, fertilization of fertile soil function of a class of fertilizers. The types of green fertilizers are mainly divided into the following five categories: nutrient-efficient green fertilizers, carbon-fixing and fertilizing green fertilizers, efficiency-enhancing and nutrient conversion efficiency green fertilizers, nutrient-balanced green fertilizers, and value-added green fertilizers. How to realize the green transformation of chemical fertilizers and the efficient and low-cost utilization of organic fertilizer resources? there are four main suggestions: (1) Rely on market mechanisms, strengthen top-level design, and build a new system of green fertilizer manufacturing; (2) Take the integrated management of nutrient resources as the core, and promote the balanced and coordinated development of organic-mass-element-micro-element fertilizers; (3) Fully play the role of scientific research platforms, and greatly develop intelligent green fertilizer products; (4) Integrate modern sensing and information technology to thoroughly promote green and efficient precision fertilization. This paper provided an overview of the background, concept, types and characteristics of green fertilizers proposed, and discussed the future development direction, in order to provide insight into the green transformation of China's fertilizer industry and the green development of agriculture in the future.

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    Non-Destructive Monitoring of Rice Growth Key Indicators Based on Fixed-Wing UAV Multispectral Images
    WANG WeiKang, ZHANG JiaYi, WANG Hui, CAO Qiang, TIAN YongChao, ZHU Yan, CAO WeiXing, LIU XiaoJun
    Scientia Agricultura Sinica    2023, 56 (21): 4175-4191.   DOI: 10.3864/j.issn.0578-1752.2023.21.004
    Abstract277)   HTML24)    PDF (2299KB)(355)       Save

    【Background】In recent years, with the rapid development of remote sensing technology, real-time and non-destructive monitoring of crop growth status has become a research hotspot. Remote sensing-derived agricultural information will provide guidance for the precise management of large-scale crops. Among various remote sensing monitoring platforms, unmanned aerial vehicles (UAVs) have attracted wide attention due to their simple operation and low cost. UAVs equipped with multispectral cameras can quickly obtain crop growth conditions.【Objective】This study attempted to combine texture information and spectral information of multispectral images of fixed-wing UAVs to explore the monitoring effect of “atlas” information on rice growth indicators.【Method】A two-year rice field experiment involving different sowing dates, varieties, planting methods and nitrogen levels was conducted. During the key growth stages of rice, remote sensing images of the rice canopy were obtained using a Sequoia multispectral camera mounted on a fixed-wing UAV. Shoot destructive sampling was conducted simultaneously to obtain leaf area index (LAI), aboveground biomass (AGB), plant nitrogen content (PNC) and other agronomic indexes of rice. Simple regression, partial least squares regression and artificial neural network algorithms were used to construct rice growth index monitoring model based on multispectral images of fixed-wing UAV. The monitoring effects of spectral texture information in different models were compared and analyzed.【Result】The quantitative relationship between vegetation index (VI), single-band texture features and rice LAI, AGB, and PNC was explored using simple linear regression. The results showed that vegetation indexes had strong correlations with LAI and AGB, with the best-performing indexes being CIRE and NDRE, with R2 values of 0.80 and 0.76, respectively. However, for PNC monitoring, vegetation indexes did not achieve ideal results, with the best-performing RESAVI and NDRE having R2 values of only 0.13 with PNC. Further analysis using simple linear regression revealed that single-band texture features did not perform well in monitoring rice growth indicators. In order to further analyze the monitoring effect of image texture on the above three indexes, normalized texture indexes (NDTI), ratio texture indexes (RTI), and difference texture indexes (DTI) were constructed by referring to the construction method of VI. Correlation analysis showed that the newly constructed texture index (TI) improved the monitoring accuracy of rice growth indicators compared to single-band texture feature but did not perform better than vegetation indexes. To combine spectral and texture information, partial least squares and artificial neural network modeling methods were adopted in this paper. VI and VI+TI were used as different input parameter combinations to construct rice LAI, AGB and PNC monitoring models. The results showed that both partial least squares and artificial neural network modeling methods significantly improved the monitoring accuracy compared to simple linear regression. The best performance was achieved using VI+TI as input variables and an artificial neural network model for validation, with validation R2 values for LAI, AGB, and PNC models increasing from 0.75, 0.72, and 0.26 to 0.86, 0.92, and 0.86, respectively, while RMSE values were significantly reduced.【Conclusion】The monitoring accuracy of rice LAI, AGB and PNC can be effectively improved by using the fixed-wing UAV to collect multispectral images of rice canopy and using the texture features and reflectance information as input parameters of the model through the model construction method of artificial neural network. The research results will provide a theoretical basis for rapid monitoring of large area crop growth.

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    Genetic Inheritance and Breeding of Stripe Rust and Powdery Mildew Resistance in Wheat
    LI ShunDa, LAN CaiXia
    Scientia Agricultura Sinica    2024, 57 (1): 1-3.   DOI: 10.3864/j.issn.0578-1752.2024.01.001
    Abstract275)   HTML62)    PDF (251KB)(205)       Save
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    Effects of Cultivation Modes on Soil Physicochemical Properties and Nitrogen Balance in Wheat Fields Under Long-Term Positioning Conditions
    GUO XinHu, MA Jing, LI ZhongFeng, CHU JinPeng, XU HaiCheng, JIA DianYong, DAI XingLong, HE MingRong
    Scientia Agricultura Sinica    2023, 56 (12): 2262-2273.   DOI: 10.3864/j.issn.0578-1752.2023.12.003
    Abstract275)   HTML35)    PDF (510KB)(266)       Save

    【Objective】 From the 2009-2010 wheat growing season, four cultivation modes were designed and set up. The effects of cultivation modes on soil physical and chemical properties, nitrogen nutrition index of winter wheat, nitrogen supply and demand balance in wheat field, uptake and utilization of nitrogen and grain yield were investigated, in order to provide a theoretical guidance for further optimizing the soil-crop system integrated management mode.【Method】Four cultivation modes were designed: local farmer mode (T1), improvement mode based on farmers (T2), high-yield and higher-yield mode regardless of production cost (T3), and soil-crop system integrated management mode (T4).【Result】After 13 wheat-maize growing seasons, the soil bulk density of surface soil for T1, T2, T3 and T4 modes decreased by 6.21%, 9.80%, 12.25% and 13.56%, respectively; the content of organic matter for four modes increased by 21.88%, 26.80%, 32.05% and 36.39%, respectively; the corresponding increases were 34.16%, 12.38%, 39.60% and 20.79% for the contents of total nitrogen; 47.85%, 48.87%, 74.49% and 62.21% for the contents of alkali-hydrolysable nitrogen, respectively; 62.73%, 36.56%, 297.93% and 68.68% for the contents of available phosphorus; 14.36%, 40.00%, 221.20% and 59.60% for the contents of available potassium, respectively. The increases of 33.96%, 10.32%, 52.77% and 19.49% were observed in the inorganic nitrogen accumulation in the 0-100 cm soil layer, respectively. Correspondingly, the pH for T1, T2, T3 and T4 modes decreased from 7.50 to 6.28, 6.68, 5.35 and 6.64, respectively. There were significant differences in grain yield and nitrogen uptake and utilization among the four cultivation modes in 2020-2022 growing season. Compared with T1 mode, the grain yield of T2, T3 and T4 modes increased by 14.14%, 27.65% and 22.52%, respectively; the nitrogen use efficiency increased by 54.80%, 19.97% and 49.15%, respectively; the nitrogen recovery efficiency increased by 72.95%, 37.54% and 48.15%, respectively; the nitrogen surplus decreased by 49.76%, 11.62% and 44.14%, respectively; the nitrogen surplus rate decreased by 24.63%, 11.62% and 26.68%, respectively. The whole plant at anthesis stage and spikes at maturity stage under T4 mode were in nitrogen supply and demand balance.【Conclusion】After 13 wheat-maize growing seasons, the soil acidification trend of 0-20 cm was obvious, and the bulk density of surface soil decreased, but the contents of organic matter, total nitrogen and available nutrients such as nitrogen, phosphorus, potassium increased for the all four cultivation modes. Meanwhile, the accumulation of inorganic nitrogen in 0-100 cm soil layer increased accordingly. Compared with other three cultivation modes, a synergistic improvement was obtained under T4 mode in soil physicochemical properties, wheat grain yield and nitrogen use efficiency. However, the nitrogen use efficiency at present under T4 mode was not high enough and still needed to be further improved. As showed by present study, further synergistic optimization in grain yield and nitrogen use efficiency could not be achieved only by reducing nitrogen input.

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    Development Strategies and Application Prospects of African Swine Fever Vaccines: Feasibility and Probability
    WANG Tao, LUO Rui, SUN Yuan, QIU HuaJi
    Scientia Agricultura Sinica    2023, 56 (11): 2212-2222.   DOI: 10.3864/j.issn.0578-1752.2023.11.014
    Abstract270)   HTML25)    PDF (572KB)(679)       Save

    African swine fever (ASF) is a fatal hemorrhagic disease in domestic pigs caused by African swine fever virus (ASFV) and the mortality of acute ASF is as high as 100%. Since ASF was introduced to China in 2018, the global prevalence and impacts of ASF were increasing. After more than three years of the epidemic of the virulent genotype II ASFV, the low virulent genotypes II and I ASFV strains emerged, resulting in an extremely complicated situation for the control and eradication of ASF in China. As an effective tool for the prevention and control of infectious diseases, the research and development of ASF vaccines have received considerable attention from the government, pig industry, vaccine manufacturers, and the scientific community. With the continuous investment of ASF research funding in recent years, based on development strategies of inactivation, attenuation, subunit, viral vector, and DNA vaccines, the unprecedented progress has been made in the development of ASF vaccines, which increased our understanding of ASF vaccine development and evaluation. In addition, some promising ASF vaccine candidates have been evaluated in preclinical models and were currently in clinical trials, showing the good application prospects, but there were still some problems hindering its further development. With a focus on the latest advances in ASF vaccines, this review summarized the advantages and disadvantages of different vaccines development strategies, the comprehensive evaluation of current ASF vaccine candidates, the development direction in the future, the challenges in developing safe and efficacious ASF vaccines, and the application prospects of ASF vaccines, so as to provide some insights for industry insiders.

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    Standardized Establishment and Improvement of Accounting System of Agriculture Greenhouse Gas Emission
    ZHANG WeiJian, SHANG ZiYin, ZHANG Jun, YAN ShengJi, DENG AiXing, ZHANG Xin, ZHENG ChengYan, SONG ZhenWei
    Scientia Agricultura Sinica    2023, 56 (22): 4467-4477.   DOI: 10.3864/j.issn.0578-1752.2023.22.009
    Abstract269)   HTML12)    PDF (463KB)(360)       Save

    Agriculture is not only the dominant source of human food and clothing, but also the potential sector of global anthropogenic greenhouse gas (GHG) emissions and mitigation, especially methane (CH4) and nitrous oxide (N2O). To standardize GHG accounting is an urgent need for agricultural carbon emission inventory compilation, carbon trading of emission reduction verification, carbon reduction subsidy and low-carbon agricultural product certification, as well as the basis for the policy making and technology selection of agricultural carbon reduction and sequestration, which is of great significance for the green-low-carbon and high-quality development of agriculture. Based on a systematic review of the relevant global specifications, guidelines, methodologies and standards of agricultural GHG accounting, this paper aimed to address the problems of imperfect monitoring and reporting systems, unsystematic accounting and calculating methods, and uncertain accounting results, by providing the following four suggestions for the establishment and improvement of agricultural GHG accounting systems. Firstly, we should further establish and improve the institutional system of the accounting system, to better clarify the subject of the main responsibility. On the existing basis of China's agricultural statistics and non-point source pollution monitoring and reporting systems, we should strengthen the construction of agricultural GHG emission monitoring (M), reporting (R) and verifying (V) system (i.e. MRV system), and supplement and improve the policy making and institutional setting, so as to clarify the main responsibilities of agricultural GHG statistical accounting and carbon reduction and sequestration. Secondly, we should further supplement and improve the accounting standards and methodologies. According to the newly issued international standards and methodologies, and the actual situation of China’s agricultural production and future development, we need to revise the agricultural components of China's Guidelines of Provincial GHG Emission Inventories. For example, the farmland carbon sequestrations of biochar application, ecological farm and well-facilitated farmland construction, photovoltaic farms and crop straw comprehensive utilization, as well as the carbon emissions of lime and urea application, ruminant livestock feeding and freshwater aquaculture, need to be supplemented into the guidelines. The accounting standards and methods of agricultural indirect GHG emissions need to be revised, and some new CCER (Chinese certified emission reduction) methodologies need to be developed for agricultural carbon trading. Thirdly, the database needs to be further renewed and upgraded. We need to strengthen scientific and technological innovations and accounting data accumulation of agricultural carbon reduction and sequestration, to renew and upgrade the basic data, action data and emission factor data of the existing accounting systems in combination with field monitoring, model estimation and literature synthesis. Fourthly, at last, it is also necessary to develop the application software supporting the accounting standards and methodologies, and carry out science popularization, technical training and application demonstration. Our suggestions could provide the references for the guideline revision of agricultural greenhouse gas emission inventories, and supports to the methodology development for trading verification of agricultural voluntary emission reduction and carbon footprint assessment of low-carbon agricultural product certification.

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    Effect of Nitrogen Application Rate and Planting Density on the Lodging Resistance and Grain Yield of Two Winter Wheat Varieties
    MU HaiMeng, SUN LiFang, WANG ZhuangZhuang, WANG Yu, SONG YiFan, ZHANG Rong, DUAN JianZhao, XIE YingXin, KANG GuoZhang, WANG YongHua, GUO TianCai
    Scientia Agricultura Sinica    2023, 56 (15): 2863-2879.   DOI: 10.3864/j.issn.0578-1752.2023.15.003
    Abstract268)   HTML17)    PDF (1133KB)(355)       Save

    【Objective】 To investigate the interactions between genotype, nitrogen application rate and planting density on the regulation of wheat lodging resistance and grain yield, so as to identify the optimal combination of nitrogen-density that matches the biological characteristics of varieties. The results provide theoretical basis and technical support for stable and abundant winter wheat yield and resistant strain cultivation. 【Method】 A split-split plot field experiment was conducted in Jiaozuo, Henan Province, China, for two consecutive years from 2020 to 2022. Two wheat varieties Xinhuamai 818 and Xinmai 26 with different lodging resistance were selected in the main plots. The nitrogen fertilizer application rates were used as split-plots, and five levels were set: no N application (N0), 180 kg·hm-2 (N1), 240 kg·hm-2 (N2), 300 kg·hm-2 (N3) and 360 kg·hm-2 (N4), the planting densities were used as split-split plots, and three levels were set: 2.25 million plants/hm2 (D1), 3.75 million plants/hm2 (D2) and 5.25 million plants/hm2 (D3). The study focused on analyzing the effects of the three-factor combination of variety, nitrogen application and planting density on the anatomical structure of wheat culms, field lodging rate and yield. 【Result】 The results showed that nitrogen application rate and planting density significantly regulated the vascular bundle structure of both wheat varieties. The number and area of big vascular bundles and the ratio of number and area of big and small vascular bundles were significantly and positively correlated with culm wall thickness and culm breaking strength, while the area of small vascular bundles was significantly and negatively correlated with culm wall thickness. Compared with Xinmai 26, Xinhuamai 818 had more big vascular bundles and larger area, while the number of small vascular bundles was equal and the area was smaller. This may be the anatomical basis for the superiority of Xinhua 818 over Xinmai 26 in terms of lodging resistance. Under the same planting density, the number and area of big vascular bundles of both wheat varieties showed a trend of increasing and then decreasing with the increase of nitrogen application rate, with the largest number and area of big vascular bundles in N3 treatment. The average increase of number and area of big vascular bundles of Xinhuamai 818 and Xinmai 26 under N3 treatment compared with the minimum treatment were 14.61%, 15.80% and 16.18%, 20.10% respectively. The number and area of small vascular bundles showed similar changes. Under the same level of nitrogen application rate, the number and area of big vascular bundles of both varieties were the largest in the low density D1 treatment. Compared with the minimum value of high density D3, the average increase in the number and area of big vascular bundles of Xinhuamai 818 and Xinmai 26 under D1 treatment were 6.14%, 5.20% and 8.95%, 11.42%, respectively.【Conclusion】 Nitrogen-density control combination D1N2 with 240 kg·hm-2 and planting density of 2.25 million plants/hm2 can optimize the vascular bundle structure, coordinate the development of big and small vascular bundles. Specifically, the number and area of big vascular bundles and the number ratio and area ratio of two vascular bundles were increased in this treatment. The combination can also increase the thickness of the culm wall between the basal nodes and improve the breaking strength of the plant. These changes realize the synchronous improvement of lodging resistance and yield of wheat. We think this treatment can be used as a suitable nitrogen-density combination pattern for high-yielding and efficient cultivation of winter wheat in high-yielding irrigation areas in northern Henan.

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    Genome-Wide Association Study of Grain Main Quality Related Traits in Winter Wheat
    DONG YiFan, REN Yi, CHENG YuKun, WANG Rui, ZHANG ZhiHui, SHI XiaoLei, GENG HongWei
    Scientia Agricultura Sinica    2023, 56 (11): 2047-2063.   DOI: 10.3864/j.issn.0578-1752.2023.11.002
    Abstract264)   HTML35)    PDF (3371KB)(502)       Save

    【Objective】The quality of wheat grain was an important factor affecting the processing quality and nutritional. Mining loci and candidate genes significantly associated with wheat grain quality traits provided a basis for broadening the understanding of the genetic mechanism of quality traits and molecular marker-assisted quality. 【Method】By measuring five quality traits, including protein content (GPC), wet gluten content (WGC), starch content (GSC), settling value (SV) and grain hardness (GH), in 259 winter wheat varieties (lines) from domestic and abroad, and conducting genome-wide association analysis in combination with 90K SNP chip, the significant association loci located were subjected to haplotype analysis. 【Result】All five traits conformed to normal distribution and showed rich variation among different environments, and the coefficient of variation of sedimentation value was the largest (20.11%-24.42%). All traits have shown highly significant differences (P<0.001) among genotype, environment, and genotype×environment, with a broad-sense heritability of 0.77-0.84. A total of 44 loci significantly associated (P<0.001) with five traits were detected by genome-wide association analysis, distributed in 19 linkage groups other than chromosomes 1D and 3D. Eighteen loci were stable in two or more environments, involving all five traits including protein content (12), wet gluten content (9), starch content (11), sedimentation value (12) and grain hardness (7), explaining 4.27%-10.98% of the genetic variation. Thirteen of them were multi-effect loci, with the largest number of multi-effect loci (7) associated with traits such as protein content, wet gluten content, settling value and starch content. The GENE-0762_631, IAAV7742 and RAC875_c66845_466 loci located on 2B, 2D and 3A chromosomes were detected simultaneously at two environmental and BLUP values with a range of 4.32%-7.07% phenotypic contribution. Through haplotype analysis of multi-effect loci present in multiple environments with high phenotypic contribution, four different haplotypes, Hap1, Hap2, Hap3 and Hap4, which were significantly associated with traits such as protein content, sedimentation value and starch content, were uncovered at the D_GDS7LZN02F4FP5_176 locus of chromosome 5D, among them Hap1 was a high starch content haplotype (P<0.001), while Hap2 and Hap3 were both haplotypes with high protein content and sedimentation value (P<0.05), and the four haplotypes accounted for 74.22%, 16.21%, 6.92% and 2.65%, respectively. The distribution frequencies of haplotypes from different sources of winter wheat were analyzed, in which the distribution frequencies of haplotype Hap2 with high protein content and sedimentation value were from high to low in the Huanghuai winter wheat regions>northern winter wheat region>abroad varieties>middle and lower reaches of the Yangtze River winter wheat region>southwest winter wheat region. Candidate genes were mined for stable genetic loci, and 10 candidate genes that might be related to wheat grain quality were screened. 【Conclusion】In the study, 18 stable loci significantly associated with grain quality traits were detected, 4 different haplotypes were identified, and 10 candidate genes related to grain quality were screened.

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    Identification and Genetic Analysis of QTL for Spike Length in Wheat
    YAO QiFu, ZHOU JieGuang, WANG Jian, CHEN HuangXin, YANG YaoYao, LIU Qian, YAN Lei, WANG Ying, ZHOU JingZhong, CUI FengJuan, JIANG Yun, MA Jian
    Scientia Agricultura Sinica    2023, 56 (24): 4814-4825.   DOI: 10.3864/j.issn.0578-1752.2023.24.002
    Abstract261)   HTML40)    PDF (2683KB)(172)       Save

    【Objective】Spike length (SL) plays an important role in determining spike structure and yield potential of wheat. Quantitative trait loci (QTL) for spike length were excavated and their genetic effects were further analyzed to provide theoretical basis for molecular breeding. 【Method】This study consisted of a population of 198 F6 recombinant inbred lines (RIL) derived from the cross between the natural mutant msf and the cultivar Chuannong 16 (MC population). The MC population and its parents were planted in five different environments including Wenjiang in 2021 and 2022 (2021WJ and 2022WJ); Chongzhou in 2021 and 2022 (2021CZ and 2022CZ); and Ya’an in 2021 (2021YA) for spike length measurement. The 16K SNP chip-based constructed high-quality and high-density genetic linkage maps were used to map QTL for spike length. Additionally, the genotype of the flanking markers for the major spike length QTL was used to analyze its genetic effect on yield-related traits and thus to evaluate its potentiality for yield improvement.【Result】A total of 14 QTL for spike length were identified and they were mainly distributed on chromosomes 1A (one), 1B (one), 2B (one), 3D (three), 4A (one), 4D (two), 5A (one), 5B (one), 7A (one), 7B (one), and 7D (one). Among them, QSl.sau.1A was detected in four environments and the best linear unbiased prediction (BLUP) value, explained 6.46% to 20.12% of the phenotypic variation, and thus was regarded as a major QTL. The positive allele at QSl.sau.1A came from the parental line msf. QTL analysis across multiple environments also detected QSl.sau.1A, indicating it exhibits minimal environmental influence and represents a major and stably expressed QTL. The effect of QSl.sau.1A was successfully verified in two populations with different genetic backgrounds. Genetic effects analysis showed that the positive allele of QSl.sau.1A showed a significant effect on improving grain number per spike (12.68%), grain weight per spike (14.99%), 1000-grain weight (5.79%), flag leaf width (2.94%), spikelet number (1.48%), and flowering date (0.61%), and a significant effect of reducing plant height (-6.47%) and effective tiller number (-36.11%).【Conclusion】A major and stably expressed spike length QTL, QSl.sau.1A, was detected on chromosome 1A. Its positive allele significantly increased grain number per spike, grain weight per spike, thousand grain weight, and spikelet number per spike, indicating its great breeding value.

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    Investigation on the Effects of Climate Change on the Growth and Yield of Different Maturity Winter Wheat Varieties in Northern China Based on the APSIM Model
    SHI XinRui, HAN BaiShu, WANG ZiQian, ZHANG YuanLing, LI Ping, ZONG YuZheng, ZHANG DongSheng, GAO ZhiQiang, HAO XingYu
    Scientia Agricultura Sinica    2023, 56 (19): 3772-3787.   DOI: 10.3864/j.issn.0578-1752.2023.19.006
    Abstract255)   HTML11)    PDF (615KB)(368)       Save

    【Objective】This study aims to clarify the impacts of climate change on the growth, development and yield of winter wheat of different maturity, so as to provide a theoretical basis for the sustainable production of wheat under future climate change. 【Method】The data about growth of two winter wheat varieties of Liangxing 99 (late-maturing) and Zhongke 2011 (early-maturing), soil, and meteorology, which were observed under different temperatures and [CO2] treatments in the open top chamber in 2017-2020, were used to calibrate and validate the APSIM (agricultural production systems simulator) model. Then the verified model was used to simulate winter wheat yield, yield composition and phenology dates under different future climate conditions (RCP 4.5 and RCP 8.5) with a baseline period of 1986-2005. And the impacts of climate change and extreme high temperature on the production potential of different maturity winter wheat varieties were analyzed. 【Result】The APSIM model was able to well simulate the phenology, yield and biomass under different air temperature and [CO2] treatments since the simulated and measured values of R2 were higher than 0.614 and the values of nRMSE were all lower than 10.6%. However, the simulation result of leaf area index (LAI) was relatively poor. For the long-term simulation results, under different climate conditions, the days from sowing to jointing were shorter than the baseline for two wheat varieties. The shortened days of early-maturing variety were smaller than those of late-maturing variety. There was no obvious change in the days from jointing to maturity between the two varieties. The yield and potential yield of the two wheat varieties were higher under the future RCP conditions than under the baseline period. The yield and potential yield were the highest under the RCP 8.5 condition in 2100s. The yield and potential yield of early-maturing variety were more remarkably increased than those of late-maturing variety. Compared with the baseline, the LAI values of the two wheat varieties increased in the early growth stage. Then, the LAI of the late-maturing variety decreased obviously in the late growth stage, while the LAI of the early-maturing variety had no obvious difference. The aboveground biomass of the two wheat varieties both increased, and the early-maturing variety increased more remarkably than the late-maturing variety. Under different RCP conditions, extreme high temperature had negative impacts on the yield and 1 000-grain weight of the two varieties of winter wheat. Extreme high temperature at flowering stage had the greatest impact on 1 000-grain weight. Compared with the normal years, the 1 000-grain weight and yield of late-maturing variety decreased obviously in extreme-high-temperature years under the RCP 8.5 condition in 2100s, while the grain number also decreased slightly. Under different RCP conditions, compared with the normal years, extreme high temperature obviously reduced the 1 000-grain weight of early-maturing variety but slightly increased the grain numbers. Thus, yield reduction of early-maturing wheat variety in extreme high temperature years was not obvious. 【Conclusion】Early-maturing variety of winter wheat will be more adaptable to future climate change. Thus, breeding of wheat varieties to adapt to climate change is one of the effective measures to cope with future climate change.

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    Screening of Low Phosphorus Tolerant Germplasm in Cotton at Seedling Stage and Comprehensive Evaluation of Low Phosphorus Tolerance
    KAYOUMU MiReZhaTiJiang, WUMAIERJIANG XiErAiLi, LI XiaoTong, WANG XiangRu, GUI HuiPing, ZHANG HengHeng, ZHANG XiLing, DONG Qiang, SONG MeiZhen
    Scientia Agricultura Sinica    2023, 56 (21): 4150-4162.   DOI: 10.3864/j.issn.0578-1752.2023.21.002
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    【Objective】To establish an evaluation system for low phosphorus tolerance in cotton varieties (lines), screen low phosphorus tolerant cotton germplasm and evaluate different types of phosphorus efficiency, and lay the foundation for studying the physiological mechanisms of low phosphorus tolerance in cotton and mining low phosphorus tolerance genes.【Method】Using 140 cotton cultivars (lines) from different cotton regions at home and abroad, 21 traits such as biomass, root-related indexes and phosphorus efficiency-related indexes were measured under low (10 μmol·L-1 KH2PO4) and normal (500 μmol·L-1 KH2PO4) phosphorus treatments in a hydroponic experiment. The index of low phosphorus stress tolerance was calculated for each index. Using the integrated affiliation function method, principal component analysis, regression analysis and cluster analysis were conducted to classify the low phosphorus tolerance of each cotton variety and to comprehensively evaluate the low phosphorus tolerance and phosphorus efficiency type of each cotton variety.【Result】Compared with the normal phosphorus treatment, the mean values of total phosphorus accumulation, total phosphorus content, aboveground dry weight and total dry matter weight of the tested cotton varieties decreased more under the low phosphorus treatment, while the mean values of root average diameter, specific root area, root tips number and phosphorus use efficiency increased. Under low phosphorus treatment, the coefficients of variation of each index ranged from 6.04% to 47.79%,the coefficients of variation of root indexes such as specific root tips density, root tips number, specific root length and root average diameter were higher than those of normal phosphorus treatment, and the coefficients of variation were 47.49%, 42.13%, 40.19% and 19.16%, respectively; the principal component analysis of the 21 indexes of low phosphorus stress tolerance showed that the cumulative variance contribution of the six principal components reached 77.21%, and the comprehensive low phosphorus tolerance value (D) was calculated using the affiliation function method. The D-value regression equation was established by multiple regression analysis to determine the six low phosphorus tolerance indices and perform systematic clustering to classify different cotton varieties (lines) into three categories: low phosphorus tolerant, intermediate and low phosphorus sensitive.【Conclusion】Total dry matter weight, phosphorus use efficiency, root fresh weight, total root length, root surface area and total phosphorus accumulation were identified as indicators for the evaluation of low phosphorus tolerance in cotton.

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    Analysis of Genetic and Breeding Selection Effects of A Major QTL-qSl-2D for Wheat Spike Length
    DONG JiZi, CHEN LinQu, GUO HaoRu, ZHANG MengYu, LIU ZhiXiao, HAN Lei, TIAN ZhaoSaShuang, XU NingHao, GUO QingJie, HUANG ZhenJie, YANG AoYu, ZHAO ChunHua, WU YongZhen, SUN Han, QIN Ran, CUI Fa
    Scientia Agricultura Sinica    2023, 56 (20): 3917-3930.   DOI: 10.3864/j.issn.0578-1752.2023.20.001
    Abstract250)   HTML33)    PDF (1330KB)(153)       Save

    【Objective】By analyzing the genetic and breeding selection effects of the stable major QTL for spike length in wheat, its genetic effects on yield-related traits were clarified, and the future breeding application potential was evaluated. The results could provide a basis for subsequent gene mining and molecular breeding of wheat. 【Method】A major QTL for spike length, named qSl-2D, was detected in multiple environments using a recombinant inbred lines population derived from the cross of Kenong9204 and Jing411, denoted as KJ-RIL; Two molecular markers closely linked to qSl-2D were developed by using the InDel sites in target interval. The genetic effects of yield-related traits based on KJ-RIL, MY-F2, NILs and natural mapping populations, were analyzed by combining genotype data of molecular markers or wheat 55K array, respectively. By genotyping the natural mapping population, the breeding selection effect of qSl-2D haplotype was parsed across different wheat regions and different ages. 【Result】QTL mapping results showed that qSl-2D could be detected in 7/10 sets of environmental data, and could explain 4.02%-10.10% of the phenotypic variation. The peak LOD of 5/10 sets of environmental data was positioned at 608.75 Mb. The results of genetic effect analysis showed that the enhancing allele of qSl-2D could significantly increase spike length in the four populations with different genetic backgrounds. In addition, it has positive effects on kernel number per spike and plant height, but has negative effects on thousand kernel weight, kernel weight per spike and yield per plant in most population backgrounds. Further analysis of plant height in KJ-RIL population showed that the enhancing allele had rod lowering effect on all internode lengths except the internode length below spike, which resulted in the insignificant increase in plant height. The results of qSl-2D haplotype analysis showed that the utilization rates of the long-spike haplotype Hap-AA-GG varied greatly in different wheat regions, with the highest utilization rate in the northern winter wheat region, accounting for 24%; while the short-spike haplotype Hap-CC-CC accounted for more than 30% in most wheat regions. Moreover, the utilization rate of qSl-2D long-spike haplotype showed a gradual decrease over time, while that of short-spike haplotype consistently maintained a higher selection trend. 【Conclusion】A stable major QTL-qSl-2D for spike length was identified, the enhancing allele of qSl-2D could significantly increase spike length under different genetic backgrounds, and had certain genetic effects on yield-related traits. The closely linked molecular markers developed in the target region can be used for the genetic improvement of wheat spike length and yield-related traits in wheat.

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    Comprehensive Fruit Quality Evaluation and Suitable Areas Selection of Newhall Navel Orange in China
    CHEN ZhiMin, CHEN XiaoLin, TAN ZhenHua, CHEN ZhaoXing, SHEN DanDan, MA YanYan, ZHENG YongQiang, YI ShiLai, LÜ Qiang, XIE RangJin
    Scientia Agricultura Sinica    2023, 56 (10): 1949-1965.   DOI: 10.3864/j.issn.0578-1752.2023.10.011
    Abstract250)   HTML38)    PDF (1220KB)(201)       Save

    【Objective】This study aimed to establish a comprehensive evaluation model in fruit quality, clarify the comprehensive grade of fruit quality and their corresponding meteorological characteristics from different Newhall Navel orange (Citrus sinensis [L.] Osb. cv. Newhall) orchards in China, so as to provide a reference for the ecological environment adaptability and suitable planting.【Method】Twenty three Newhall orchards in different ecological environments of China were selected to measure fruit external and internal quality indicators. Correlation analysis, principal component analysis and cluster analysis were used to identify the core indicators, and the comprehensive evaluation models of fruit quality were established by analytic hierarchy process (AHP), principal component analysis (PCA) and fuzzy comprehensive appraisal (FCA), respectively. The optimal algorithm model and fruit grade classification threshold were determined and verified with sensory quality evaluation. Meanwhile, the comprehensive quality grades and the characteristics of corresponding ecological factors of Newhall navel orange fruit from different producing areas were explored.【Result】The fruit comprehensive quality of 23 Newhall orchards showed obvious regional characteristics. The fruit in southern Jiangxi and southern Hunan had higher total soluble solid and solid acid ratio, while the fruit in western Hunan and the upper and middle reaches of the Yangtze River had better fruit external color indexes and higher titratable acid. The quality indexes were correlated to varying degrees. Five core indexes were selected by principal component analysis combined with cluster analysis, including comprehensive color index, fruit weight, soluble solids, solid acid ratio, and vitamin C content. At the same time, AHP model was determined as the comprehensive evaluation model of fruit quality with the best fitting degree of sensory quality index: Y (comprehensive value) = 0.06× comprehensive color index + 0.26× single fruit weight +0.16× soluble solid content +0.42× solid acid ratio +0.11× vitamin C content (standardized value). The comprehensive fruit quality indicators of different Newhall orchards were ranked, and the classification threshold was determined as follows: ≥0.60 was the first-class orchards, mainly concentrated in southern Jiangxi, southern Hunan and eastern Guangdong, with active accumulated temperature, effective accumulated temperature, maximum sunshine hours and surface temperature; 0.45-0.60 was the second-class orchards, mainly concentrated in northern Guangxi and western Fujian, characterized by higher temperature accumulation and rainfall; 0.30-0.45 was the third-class orchards, mainly concentrated in western Hunan and the middle and upper reaches of the Yangtze River, with relatively lower rainfall and temperature accumulation; <0.30 was the fourth-class orchards, mainly distributed in southern Zhejiang, with the highest rainfall.【Conclusion】The core indicators of the comprehensive quality of citrus fruits were identified by PCA, and the AHP model with the optimal for the Newhall fruit comprehensive evaluation by combining the eigenvalues of each principal component to achieve automatic assignment of AHP judgment matrix. The ecological factors of different grades of orchards were significantly different. These results provided algorithms and data support for the development of the decision system based on "suitable planting" of citrus varieties in different ecological environment.

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    The Modification of Gene Editing Vector for Efficient GFPuv Fluorescence Screening and Its Application in Potato Genetic Transformation
    DU JingYa, CHEN KaiYuan, PU Jin, ZHOU HuiYing, ZHU GuangTao, ZHANG ChunZhi, DU Hui
    Scientia Agricultura Sinica    2023, 56 (11): 2223-2236.   DOI: 10.3864/j.issn.0578-1752.2023.11.015
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    【Objective】The improvement and innovation of screening markers contributes to the development of transgenic technology, among which the visual screening markers are widely modified for better effect. Recent studies revealed that an enhanced Yellow Green Fluorescent like Protein (eYGFPuv (GFPuv)) obtained by mutation can emit strong and stable green fluorescence under 365 nm UV light irradiation and be easily observed. Constructing the gene editing vector with GFPuv fluorescence screening marker and carrying out experiment application and verifications in potato genetic transformation will provide technical support for the screening of positive transgenic plants in potato transformation, and lay the foundation for using genome editing technology to create potato male sterile lines in the future. 【Method】By using homologous recombination, the GFPuv expression framework and gene editing element Cas9_sgRNA were successively recombined into pCAMBIA2300 vector, and then with this new designed vector the Agrobacterium-mediated transient expression assay was conducted in tobacco plants. Six editing vectors with potato anther development conservative genes were constructed using this modified vector. The A. rhizogenes strains Ar qual and MSU440 harbouring these vectors were transformed into the potato stem segments respectively, and then the A. rhizogenes-induced hairy roots with green fluorescence were observed and counted under the portable UV lamp. The transformation efficiency and editing efficiency of these vectors were analyzed using hairy root transformation system in two different potato genotypes. In the end, the modified vectors were applied to produce transformed potato plants with modifications on target genes. 【Result】A novel gene editing vector pCAMBIA2300MGFPuv-sgRNACas harbouring a GFPuv fluorescence marker was successfully constructed, and the transient transformation in tobacco plants confirmed that the GFPuv expression framework was expressed successfully. The hairy roots with green fluorescence were screened after the transformation with two kinds of A. rhizogenes, and an additional supplement of kanamycin (Kan) significantly increased the proportion of positive fluorescent roots. Although the transformation rates of the two strains were not significantly different, the hairy roots of MSU440 formed faster. Furthermore, the transformation rates and editing rates of editing vectors for six potato anther development conservative genes in two different potato genotypes were the same, but the editing rates of six target sites differed significantly. Potato genetic transformation using the modified vector confirmed that GFPuv fluorescence could be used for the screening of transgenic callus and plants in potato. 【Conclusion】The hairy root transformation system mediated by A. rhizogenes is an essential approach to verifying the efficiency of gene editing, and GFPuv fluorescence can be used in the screening of transgenic plants in potato transformation.

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    Status, Existing Problems and Strategy Discussion on Northward Expansion of Winter Rapeseed in China
    LIU ZiGang, WEI JiaPing, CUI JunMei, WU ZeFeng, FANG Yan, DONG XiaoYun, ZHENG GuoQiang
    Scientia Agricultura Sinica    2023, 56 (15): 2854-2862.   DOI: 10.3864/j.issn.0578-1752.2023.15.002
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    Since the 1950s, with the introduction and application of winter rapeseed (Brassica napus) in China, it has led to the rapid transformation, i.e., replacing winter turnip rape by winter oil rape, in the Yangtze River Basin being the main production areas of winter rapeseed in China. In the late 1980s, with the continuous breakthroughs in cold tolerance breeding, the planting area of winter oil rapeseed continued to extend northward. Winter oil rapeseed had replaced winter turnip rapeseed in the main production areas in China, such as the HuangHuai River Basin, Weihe River Basin, and Weibei Dry Plateau. In recent years, strong cold resistant cabbage type winter oil glycerol 4 and other varieties have been developed, which can replace winter turnip rapeseed in arid and cold regions of northern China, achieving doubled yield of winter rapeseed, “double low” quality, and suitable machine harvesting for lodging resistance. The essence of the successful northward migration of winter rapeseed was the northward migration of winter oil rapeseed in China, namely cold resistant varieties of winter oil rapeseed replaced winter turnip rapeseed in the original production area, which have greatly promoted the development of winter rapeseed industry. Nevertheless, the northward migration of winter turnip rapeseed faces completely different difficulties. Since 1955, the northward migration trial of winter turnip rapeseed has been terminated by the introduction of spring oil rapeseed into the planting regions of spring turnip rapeseed at the same time. In the subsequent trial, there is a deviation in the research direction on techlonogies of the northward migration, i.e., solely paying close attention to the cold resistance, while ignoring drought tolerace of varieties which have been migrated into the northward migration area with further reduction in precipitation. There was resulting in technology output not meeting the actual needs of the industry. As a result, the northward migration practice has been carried out for decades and has not yet formed a stable winter rapeseed planting area outside of traditional production areas. In recent years, the original planting area has also continued to shrink, and the northward migration of winter turnip rapeseed has had little effect. In practical condition, the main challenge faced by the northward migration of winter turnip rapeseed is water limitation and the combination of drought and cold stress. The low comparative efficiency is the leading factor in the predicament of industrial development. In recent years, the strong cold-tolerant varieties of winter oil rapeseed developed can stably overwinter in northern cold and arid regions, replacing the varieties of winter turnip rapeseed, significantly improving yield, quality, planting efficiency of winter rapeseed, etc., which is the hope for winter rapeseed in strong winter regions to break through industrial difficulties. We have reviewed the history of winter rape northward-extension in China, achievements and existing problems. The reasons for the dilemma of northward extension were analyzes, and suggestions were made. The revolution of replacing winter turnip rape with winter oilseed rape should be promoted to meet the challenges in winter rape industry development in north China.

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    Influence of Future Climate Change on the Climate Suitability of Potato Cultivation in China
    ZHANG ZhiLiang, HE ZhiHao, RU XiaoYa, JIANG TengCong, HE YingBin, FENG Hao, YU Qiang, HE JianQiang
    Scientia Agricultura Sinica    2023, 56 (18): 3530-3542.   DOI: 10.3864/j.issn.0578-1752.2023.18.004
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    Objective】As the fourth staple food crop in China, potato suitability evaluation is of great significance to ensure national food security. Based on climate data, this study constructed an integrated species distribution model to predict the climate suitable area of potato in China in the future, and provided an important scientific reference for optimizing potato planting in China.【Method】In this study, the future climate data derived from six different global climate models (GCMs) were used to drive an ensemble of five different species distribution models (SDMs) to simulate the temporal and spatial distribution characteristics of climate suitable areas of potato cultivation in China in the historical (1970-2000) and four future (2021-2040, 2041-2060, 2061-2080, and 2081-2100) periods under four greenhouse gas emission scenarios (ssp126, ssp245, ssp370, and ssp585). 【Result】 (1) The precipitation in the wettest month, the highest temperature in the warmest month, and the average temperature in the coldest quarter were the main meteorological factors that affected the climate suitability of potato in China, with their contribution rates of 54.7%, 21.4% and 18.1%, respectively. (2) In four scenarios of greenhouse gas emission, the prediction results of various suitable areas were basically the same, showing the similar trends that the areas of suitable and low suitable would become larger, while the area of high suitable would become smaller. Only in Hainan, Tibet, Xinjiang and some other regions, the climate was not suitable for potato planting. The suitable potato planting areas (including both suitable and high suitable) exceed 50% in all cases. (3) In the future, the low suitable and suitable areas for potato planting will increase greatly, while the high suitable areas will decrease. The order of areas of different suitable grades would remain: suitable areas>low suitable areas>high suitable areas. (4) With the increase of greenhouse gas emission level, the high suitable area in China would be greatly reduced. For spatial distribution, the high suitable areas were mainly in Northeast China, Gansu, western Xinjiang, and some parts of southwest China. From the perspective of time, the future climate change would greatly affect the northwest of Shaanxi, the middle and lower reaches of the Yangtze River, the central and western Inner Mongolia and other regions. The climate suitability of potato planting would obviously decrease. 【Conclusion】In this study, the integrated species distribution models were constructed to predict the temporal and spatial distribution characteristics of potato climate suitable areas in the future. Northeast, Gansu, Southwest and other regions of China could be the main potato planting areas, while Xinjiang and other regions could be the main development areas. The rest regions should be given priority to the development of other staple crops and cash crops according to local conditions.

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    Effect of Porcine ECR1-Like Immune Adhesion on PAMs Capturing GFP-Escherichia coli
    ZHANG Zheng, LING XiaoYa, FAN KuoHai, SUN Na, SUN PanPan, SUN YaoGui, LI HongQuan, YIN Wei
    Scientia Agricultura Sinica    2023, 56 (19): 3905-3916.   DOI: 10.3864/j.issn.0578-1752.2023.19.016
    Abstract241)   HTML8)    PDF (1411KB)(182)       Save

    【Objective】The aim of this study was to investigate whether the immune adherence function of porcine erythrocyte complement receptor type 1-like (ECR1-like) could promote porcine alveolar macrophages (PAMs) to capture sensitized genetic engineering bacteria GFP-E. coli, in order to explain the molecular mechanism of porcine erythrocyte immunity and its role in innate immunity. 【Method】The level of GFP-E. coli captured by PAMs was detected by flow cytometry, colony plate counting and RT-PCR, and the effect of porcine ECR1-like immune adherence on the capture of GFP-E. coli by PAMs was analyzed. Flow cytometry and cellular immunofluorescence technique were used to detect the changes of immune adherence function of porcine erythrocytes, and the number of porcine ECR1-like after the sensitized GFP-E. coli with ECR1-like immune adherence was removed by PAMs. 【Result】Flow cytometry showed that the average fluorescence intensity of PAMs in porcine erythrocyte adhesion group was significantly higher than that in blank control group (P<0.001), while the positive rate of PAMs cells in porcine erythrocyte adhesion group was significantly higher than that in blank control group (P<0.05). Colony smear count showed that the capture of GFP-E. coli by PAMs in erythrocyte adhesion group was significantly higher than that in blank control group (P<0.05). RT-PCR showed that the relative quantity of GFP-E. coli in PAMs of erythrocyte adhesion group was significantly higher than that of blank control group (P<0.01). Further blocking CR1-like on the surface of porcine erythrocyte, flow cytometry showed that the average fluorescence intensity of PAMs decreased to 256 301.56±9 208.85 (P<0.001), and the positive cell rate of PAMs decreased to (88.32±0.92)% (P>0.05). Colony count showed that the capture of GFP-E. coli in PAMs decreased to (136 666±8 818) CFU/mL (P<0.05), and RT-PCR showed that the relative quantity of GFP-E. coli in PAMs decreased significantly (P<0.01). Using cell flow and circulation interaction technique, it was found that the average fluorescence intensity of GFP-E. coli sensitized by porcine erythrocyte immune adherence decreased from 2 892.18±47.76 before circulation to 2 407.43±141.78 (P<0.05), and the positive cell rate decreased from (20.58±0.36)% before circulation to (17.39±0.23)% (P<0.05). The adhesion level was significantly lower than that before circulation. Meanwhile, the results of indirect immunofluorescence test showed that the average fluorescence intensity of porcine ECR1-like decreased from 344.33±37.92 before to 291.56±11.99 (P<0.05), and the positive cell rate decreased from (30.20±1.24)% before to (28.27±0.64)% (P<0.05). 【Conclusion】Porcine ECR1-like promoted the capture of sensitized GFP-E.coli by PAMs through its immune adhesion function. After PAMs removed sensitized GFP-E. coli adhered to the surface of porcine erythrocyte, the activity of CR1-like of porcine erythrocyte decreased, and the immune adhesion function decreased too.

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    Screening, Identification and Control Efficacy Analysis of Trichoderma Strains Against Maize Pythium Stalk Rot
    GUO Ning, SUN Hua, MA HongXia, LIU ShuSen, ZHANG HaiJian, SHI Jie, ZHENG XiaoJuan, DONG YueGuang
    Scientia Agricultura Sinica    2023, 56 (22): 4453-4466.   DOI: 10.3864/j.issn.0578-1752.2023.22.008
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    【Objective】The objective of this study is to screen Trichoderma strains which have inhibitory effect on the Pythium spp. causing maize stalk rot, and to clarify their taxonomic status, control efficacy and antifungal mechanism. This study will provide important resources for the research and development of biocontrol agent against Pythium stalk rot.【Method】For the antagonistic strains screening, the inhibitory effect of Tichoderma strains on P. inflatum, P. arrhenomanes and P. aristosporum was tested by measuring the mycelia growth. The taxonomic status of Tr21 was determined by morphological and molecular characteristics. The effect of Tr21 on the mycelia morphology of Pythium spp. was observed in the laboratory. In order to analyze the effect of Tr21 fermentation broth on the membrane permeability of Pythium spp., propyridine bromide (PI) dye solution was used to stain, and the absorbance values of protein and nucleic acid in mycelia supernatant at different treatment times were detected. The effect of Tr21 fermentation broth on germination characteristics of maize seeds was tested by seed soaking with different concentrations of fermentation broth. The control efficacy of Tr21 on stalk rot was confirmed through greenhouse pot and field inoculation experiments.【Result】From the 109 strains of Trichoderma spp., seven strains were screened with antagonistic activity against P. inflatum, P. arrhenomanes and P. aristosporum, and the inhibition rate was above 60%. The inhibition rate of Tr21 to three Pythium species reached 100%, the inhibition rate of 5×, 10× and 20× diluent to three Pythium species reached 100%, and the inhibition rate of 50× diluent to three Pythium species was also more than 55.56%. Tr21 strain was identified by morphological and molecular biology as T. afroharzianum. The results of microscopic observation showed that the fermentation broth of Tr21 could cause mycelial malformations, such as rough mycelia, increased mycelial branching, shortened nodes, and overflow of mycelia contents. The result of PI fluorescence stain showed that the cell membrane of three Pythium species was damaged by Tr21 fermentation broth, and the PI dye was more likely to penetrate the damaged cell membrane into the mycelium and stain the mycelia red. The results of nucleic acid and protein leakage showed that the absorbance values of the mycelia treated by the fermentation broth changed greatly. After treatment for 5 h, the OD260 increased by 0.08 and OD280 increased by 0.10, 0.11 and 0.10, respectively, indicating that the membrane of the mycelia was damaged, leading to the overflow of mycelia contents. The different concentrations of Tr21 fermentation broth had no effect on the germination characteristics of maize seeds, and the 20× diluent had the best effect on germination and growth of seeds. The results of pot experiment showed that 5× diluted fermentation broth of Tr21 had the best control efficacy on Pythium stalk rot caused by three Pythium species, which was 60.67%, 63.15% and 59.66%, respectively. The control efficacy on Pythium stalk rot of 5× diluent was the highest, reaching 82.25%, with a mass ratio of 1﹕100 (5× diluent to seed).【Conclusion】An effective T. afroharzianum strain Tr21 was obtained for preventing and controlling of maize Pythium stalk rot. The fermentation broth of Tr21 can lead to mycelia malformation, breakage, cell membrane damage and contents leakage, etc. In conclusion, the T. afroharzianum strain Tr21 is a promising biocontrol microbial.

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    Effect of Temperature on the Occurrence of Cotton Verticillium Wilt and Host Defense Response
    ZHANG YaLin, JIANG Yan, ZHAO LiHong, FENG ZiLi, FENG HongJie, WEI Feng, ZHOU JingLong, ZHU HeQin, MA ZhiYing
    Scientia Agricultura Sinica    2023, 56 (23): 4671-4683.   DOI: 10.3864/j.issn.0578-1752.2023.23.009
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    【Objective】The objective of this study is to analyze the effect of different temperatures on the occurrence of cotton Verticillium wilt and the mechanism of regulating host defense response, reveal the dual effects of temperature on pathogen and host, and to provide a theoretical basis for the green control and temperature regulation of this disease.【Method】Cotton Verticillium wilt resistant variety Zhongzhimian 2 (ZZM2) and susceptible variety Jimian 11 (JM11) were employed as experimental materials, indoor experiments and disease nursery experiments were jointly used to set constant temperatures (22, 25, 28, and 32 ℃) and natural temperature variation to determine the effect of temperature on the growth, infection and colonization of Verticillium dahliae, and the occurrence of cotton Verticillium wilt. The mechanism of temperature regulation of cotton host defense response was analyzed by utilizing indicators such as reactive oxygen species (ROS) outbreak, H2O2 content, callose accumulation, and the expression of defense-related genes.【Result】On the culture media, 25 ℃ was the optimal temperature for the mycelial growth of V. dahliae, and the range of 22-28 ℃ was suitable for spore yield. Compared with the culture media, the leaf extracts of resistant variety ZZM2 and susceptible variety JM11 had a promoting effect on the growth of V. dahliae, and JM11 promoted stronger. When the temperatures were between 25 and 28 ℃, both ZZM2 and JM11 suffered from severe Verticillium wilt, and low temperature 22 ℃ and high temperature 32 ℃ were not conducive to the occurrence of Verticillium wilt. Meanwhile, under 25 ℃ treatment, the colonization ability of V. dahliae in cotton was strong, JM11 was more susceptible to V. dahliae infection than ZZM2, which was basically consistent with the results of the cotton Verticillium wilt disease index. Furthermore, temperature significantly affected the host defense response of cotton: compared with 22-28 ℃, whether inoculated with V. dahliae or not, the ROS outbreak produced by ZZM2 and JM11 under 32 ℃ treatment was stronger; under 25 ℃ treatment, the H2O2 content in ZZM2 and JM11 leaves was the lowest; under 32 ℃ treatment, the accumulation of callose in ZZM2 and JM11 leaves was higher, which was 2.04 and 1.80 times higher than that of the untreated control, respectively; the expression level of PAL, POD, and PPO defense-related genes in cotton leaves decreased under treatments at 25-28 ℃, which was lower than that under treatments at 22 and 32 ℃.【Conclusion】Temperature has a dual effect on the growth of V. dahliae and host defense response, which in turn affects the occurrence of cotton Verticillium wilt. Regardless of constant temperature or natural temperature variation, 25-28 ℃ are beneficial for the colonization of V. dahliae in cotton, significantly reduce the host defense response, and lead to severe cotton Verticillium wilt.

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    Response and Drip Irrigation Re-Watering Compensation Effect of Spring Wheat Roots to Drought Stress with Different Drought Tolerance Varieties
    WANG RongRong, CHEN TianPeng, YIN HaoJie, JIANG GuiYing
    Scientia Agricultura Sinica    2023, 56 (24): 4826-4841.   DOI: 10.3864/j.issn.0578-1752.2023.24.003
    Abstract234)   HTML45)    PDF (1109KB)(200)       Save

    【Objective】The objective of this study is to investigate the differences in morphological and physiological responses of root growth of drip irrigated spring wheat with different drought sensitivity to stage drought stress, to further elaborate the physiological mechanisms of drought resistance and water conservation in drip irrigated spring wheat in Xinjiang, and to provide a theoretical basis for further water-saving and high-yield in Xinjiang wheat region. 【Method】 From 2021-2022, the strong drought resistance variety Xinchun 6 and the weak drought resistance variety Xinchun 22 were used as the test materials by using the soil column cultivation method. Mild (T1 and T3, 60%-65% FC, FC is the field capacity) and moderate (T2 and T4, 45%-50% FC) drought stress treatments were conducted during the tillering and jointing stages, with conventional irrigation as the control (CK, 75%-80% FC), the effects of pre-reproductive drought stress on root morphological characteristics (root length density (RLD), root volume density (RVD)), antioxidant system (malondialdehyde (MDA), superoxide dismutase (SOD), peroxidase (POD)), osmoregulation substance (proline (Pro), soluble sugars (SS)) and spatial and temporal characteristics of root activity were studied. The compensatory effect of drip irrigated spring wheat root growth on drought-rehydration was analyzed.【Result】RLD and RVD showed a trend of increasing and then decreasing with increasing drought stress, and under mild drought (T1 and T3) conditions, RLD and RVD in the 20-60 cm soil layer were significantly increased. The MDA content in the root of each soil layer showed an upward trend with the intensification of stress, while SOD, POD, Pro, and SS all increased first and then decreased with the intensification of drought, and gradually increased with the deepening of the soil layer. After rehydration of T1 treatment, root morphological characteristics, antioxidant enzyme activity, osmotic substances and root activity all reached the maximum value, which in turn increased the yield by 2.77% to 19.58% compared to the rest of the treatments. Stepwise regression analysis showed that RVD and SS were important determinants of yield, RLD, SOD and SS were the most significant indicators of Xinchun 6 drought resistance; RLD, MDA and POD were the most significant indicators of Xinchun 22 drought resistance.【Conclusion】Spring wheat maintains 60%-65% FC during the tillering and jointing stages, after drip irrigation and rehydration, it increases the distribution proportion of roots in the 20-60 cm soil layer, enhances the root system’s ability to remove reactive oxygen species and osmotic adjustment, delays root senescence and improves root physiological characteristics, thus increasing yield.

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    40 Years’ Change Characteristics of Soil Basic Properties in the Main Planting Area of Winter Oilseed Rape
    HUO RunXia, ZHANG Zhe, LI WenPing, ZHANG YangYang, LIAO ShiPeng, REN Tao, LI XiaoKun, LU ZhiFeng, CONG RiHuan, LU JianWei
    Scientia Agricultura Sinica    2023, 56 (23): 4696-4705.   DOI: 10.3864/j.issn.0578-1752.2023.23.011
    Abstract232)   HTML22)    PDF (722KB)(230)       Save

    【Objective】The objective of this study was to investigate the changes in basic physical and chemical properties of soils in the main winter oilseed rape producing areas in the Yangtze River Basin over the past 40 years, and to clarify the characteristics of changes in comprehensive soil fertility of arable land in winter rape growing areas, in order to provide a scientific basis for conservation and soil fertility improvement in low and middle yielding fields in the Yangtze River Basin.【Method】By collecting and organizing the data from published literatures, master’s and doctoral dissertations at home and abroad in the past 40 years, the temporal variation characteristics of basic soil properties in winter oilseed rape growing areas in the Yangtze River Basin were analyzed. Then the variation characteristics of integrated soil fertility (IFI) and its correlation with basic soil physical and chemical properties were evaluated. 【Result】The average values of soil organic matter, total nitrogen, available phosphorus and potassium, and pH in the main winter oilseed rape producing areas of the Yangtze River Basin were 18.54 g·kg-1, 1.16 mg·kg-1, 8.60 mg·kg-1, 42.90 mg·kg-1, and 6.26 during the period of 1981-1990, respectively, but enhanced to 25.60 g·kg-1, 1.41 mg·kg-1, 18.66 mg·kg-1, 108.98 mg·kg-1, and 6.31 by 2016-2020, respectively. Clearly, the soil basic physical and chemical properties have been improved extensively in planting area of winter oilseed rape in the Yangtze River Basin. The average annual increase rate was 1.2% in soil organic matter and 0.7% in soil total nitrogen. Soil available phosphorus and available potassium were enhanced by 3.0% and 4.0% per year, respectively. Soil pH remained stable in the past 40 years, with the mean range of 6.21-6.45 among different periods. Based on the improved Nemerow index method, soil IFI value was also found enhanced in the past four decades. Compared with the mean IFI in the period of 1981-2000, the value was significantly increased by 14.8%-30.4% during the period of 2001-2020. The IFI was positively correlated with soil organic matter, pH, total nitrogen, available phosphorus and available potassium. Path analysis showed that soil available potassium was the most important index affecting IFI, followed by soil total nitrogen and available phosphorus. 【Conclusion】The basic physical and chemical properties and comprehensive fertility of the soil was significantly improved in the past 40 years in the planting area of winter oilseed rape. Developing the planting area of oilseed rape would be benefit for soil fertility and productivity improvement in the Yangtze River Basin, especially for the farmland with low yield productivity.

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    Effects of Multiple Green Manure After Wheat Combined with Different Levels of Nitrogen Fertilization on Wheat Yield, Grain Quality, and Nitrogen Utilization
    ZHANG WenXia, LI Pan, YIN Wen, CHEN GuiPing, FAN ZhiLong, HU FaLong, FAN Hong, HE Wei
    Scientia Agricultura Sinica    2023, 56 (17): 3317-3330.   DOI: 10.3864/j.issn.0578-1752.2023.17.007
    Abstract232)   HTML19)    PDF (587KB)(349)       Save

    【Objective】 Aiming at the problems of large nitrogen input, single fertilizer source, low nitrogen utilization rate, and poor quality of wheat in spring wheat cultivation in Hexi areas of Gansu Province, the objective of this study is to explore the effects of suitable green manure and reduced nitrogen fertilizer cultivation techniques on grain yield and quality, and nitrogen absorption and utilization of spring wheat, and to provide a theoretical basis for high yield, high quality, and green production of wheat in Hexi irrigation areas. 【Method】 A split plot experiment was conducted from 2019 to 2021 in the Hexi oasis irrigation areas of Gansu Province. Two cropping patterns of multiple green manure after wheat (W-G) and sole wheat (W) were set in the main plot. There were five N fertilizer levels in the sub-plot: 100% of conventional N fertilizer by the farmer (180 kg·hm-2, N4), 85% of conventional N fertilizer (N3), 70% of conventional N fertilizer (N2), 55% of conventional N fertilizer (N1), and no N fertilizer (N0). 【Result】 Multiple green manure after wheat combined with 85% N application (W-G-N3) was effectively increased wheat grain yield and biomass. The grain yield of W-G-N3 was increased by 16.7%-18.4% and 13.6%-34.4%, respectively, compared with the 85% N application (W-N3) and conventional N application (W-N4) treatments for the sole wheat. The biomass of W-G-N3 was increased by 11.3% (2020) and 5.2%-11.6% (2020 to 2021), respectively, compared with the W-N3 and W-N4 treatments. The increase of grain yield was greater than that of biomass, thus, the W-G-N3 treatment had higher harvest index, which was 4.9%-15.9% and 8.0%-20.5% higher than that of W-N3 and W-N4 treatments. Meanwhile, the W-G-N3 treatment improved grain quality of wheat by increasing protein content, sedimentation value, and wet gluten content, among which, the protein content, sedimentation value, and wet gluten content of W-G-N3 were increased by 12.3%-16.1%, 28.7%-47.2%, and 10.7%-11.1%, respectively, compared with W-N3; The protein content of W-G-N3 was increased by 8.9%-12.4% compared with W-N4, but the differences in sedimentation value and wet gluten content between W-G-N3 and W-N4 were not significant. In addition, the W-G-N3 treatment was beneficial to promote nitrogen uptake and conversion to grain yield in wheat compared with W-N3 and W-N4 treatments, in which the N uptake was increased by 42.2%-58.9% and 35.2%-45.0%, N use efficiency was increased by 12.0%-20.6% and 5.9%-20.4%, respectively, and N partial factor productivity was increased by 3.6%-18.3% and 28.1%-58.1%, respectively. The W-G-N3 treatment could compensate for the reduction of N agronomic efficiency, which was 74.2%-80.0% higher than W-G-N4 treatment. The correlation analysis showed that multiple green manure after wheat combined with moderate reduction of N fertilizer increased grain yield by promoting efficient nitrogen uptake and utilization, and also significantly improved grain nutritional quality. 【Conclusion】 The combination of multiple green manure after wheat with 85% (153 kg·hm-2) nitrogen application is the suitable cropping pattern and nitrogen application level to boost wheat yield, improve wheat grain quality, and increase nitrogen use efficiency in Hexi oasis irrigated areas.

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    Pigment Identification and Gene Mapping in Red Seed Coat of Soybean
    CAO Jie, GU YongZhe, HONG HuiLong, WU HaiTao, ZHANG Xia, SUN JianQiang, BAO LiGao, QIU LiJuan
    Scientia Agricultura Sinica    2023, 56 (14): 2643-2659.   DOI: 10.3864/j.issn.0578-1752.2023.14.002
    Abstract230)   HTML21)    PDF (3120KB)(430)       Save

    【Objective】To identify the key genes controlling anthocyanin synthesis and accumulation, to uncover changes in anthocyanin content of the seed coat during seed development, and the primary anthocyanin components responsible for the red seed coat of Taixingaijiaohong (TXAJH); and to lay the groundwork for a thorough understanding of the regulatory mechanism of red seed coat formation.【Method】Using ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-ESI-MS/MS), the anthocyanin composition and concentration of the yellow seed coat of soybean Suinong 14 (SN14) and the red seed coat of soybean TXAJH at various developmental stages were identified. The potential areas of red testa-related genes were first identified using bulked segregant analysis (BSA) on the recombinant inbred lines (RILs) made by crossing SN14 and TXAJH. Based on this discovery, we performed marker linkage analysis to restrict the candidate intervals and predict the candidate genes, and qRT-PCR to confirm the expression of the anticipated candidate genes.【Result】When seed coats from the four developmental phases of SN14 and TXAJH were analyzed, a total of 12 anthocyanins were discovered. Cluster analysis of total anthocyanins revealed substantial changes in the seed coat's anthocyanin composition between TXAJH and SN14 as well as between TXAJH before and after color development. The anthocyanin content of the SN14 seed coat gradually decreased as the seed developed, whereas the TXAJH seed coat's content increased quickly and remained stable. After the development of the seed coat's color, the anthocyanin contents of SN14 and TXAJH showed highly significant differences, and at the mature stage, the TXAJH seed coat's anthocyanin content was more than 200 times that of SN14. The crimson coloring of the TXAJH seed coat was largely due to cyanidin-3-O-glucoside (Cy-3-glu), peonidin-3-O-glucoside (Pn-3-glu), and petunidin-3-O-glucoside (Pt-3-glu). The candidate interval for the red seed coat gene on chromosome 8 was discovered at 8.66 Mb by BSA-seq association analysis. 27 polymorphic markers were used in the marker linkage analysis, which produced 10 haplotypes and reduced the candidate interval to 702 kb. Nonsynonymous variations in 37 genes between the parents were found during this interval, these include the genes for encode the anthocyanin reductase 1 (Glyma.08g062000), the bHLH transcription factor (Glyma.08g061300 and Glyma.08g063900), and the MYB transcript factor (Glyma.08g059900). These genes may be involved in regulating the biosynthesis of anthocyanins, and anthocyanin reductase 1 can convert anthocyanins to proanthocyanidins (PA). The results of gene expression analysis revealed that candidate genes and genes related to the anthocyanin biosynthesis pathway had comparable expression patterns in SN14 and TXAJH, and both were expressed at lower levels in SN14 and at higher levels in TXAJH. It was discovered that there was a significant link between the principal constituents of seed coat anthocyanins and the level of candidate gene expression.【Conclusion】The anthocyanin makeup of SN14 and TXAJH's seed coats differed, and Cy-3-glu, Pn-3-glu, and Pt-3-glu may be to blame for the TXAJH's seed coat's red hue. According to predictions, Glyma.08g059900, Glyma.08g061300, Glyma.08g062000, and Glyma.08g063900 will likely be a candidate gene for the red seed coat, in which Glyma.08g059900, Glyma.08g061300, and Glyma.08g063900 may control a number of anthocyanin biosynthesis pathway genes.

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    Current Situation of Breeding and Popularization of Short-Growth- Period Winter Rapeseed Varieties for Rice-Rice-Rapeseed Mode
    LI RongDe, HE Ping, LUO LiXia, SHI MengYa, HOU Qian, MA ZhenGuo, GUO RuiXing, CHENG HongTao
    Scientia Agricultura Sinica    2024, 57 (5): 846-854.   DOI: 10.3864/j.issn.0578-1752.2024.05.002
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    The self-sufficiency rate of edible vegetable oil is less than 31 percent in China, with a high degree of import dependence. Rapeseed is the only winter oilseed crop with a wide range of suitable planting region, and it is an important source of edible vegetable oil in China. Planting more rapeseed is an important measure to guarantee national edible oil supply security. Making full use of the winter fields in the southern double cropping rice area to promote “rice-rice-rapeseed” production is an important approach to expand the planting area of rapeseed. The area suitable for the “rice-rice-rapeseed” production mode is mainly distributed in the double cropping rice area of Hunan, Jiangxi, Guangxi and Hubei provinces in China, with a potential area of about 1.87 million hm2. According to the conditions of temperature and light resources, three suitable areas for the “rice-rice-rapeseed” production include the ample area, tightly balanced area and the constrained area. All the areas require early-maturing rapeseed varieties with a growth period of around 180 days, which are suitable for being sown in mid- to late October and harvested in mid- to late April. Among a total of 75 new rapeseed lines participated in the early-maturity group of the national rapeseed variety trials from 2013 to 2022, the average growth period ranged from 169.3 to 185.5 days, and the average yield was 1 635.90-2 228.55 kg·hm-2, with 22 varieties out yielded the check variety. There are 72 early-maturing winter oilseed rape varieties with a growth period less than 190 days were registered by the end of May 2023. These varieties are suitable to be used in the “rice-rice-rapeseed” mode, and most of them are hybrid varieties with low erucic acid and low glucosinolate quality. 11 varieties, Yangguang 131, Fengyou 730, Fengyou 320, Fengyou 847, Ganyouza 906, Shengguang 127, Xiangyou 420, Jingyou 69, Fengyou 112, Huayouza 652, Ganyouza 1009, are the most promoted and applied early-maturing winter rapeseed varieties in the “rice-rice-rapeseed” production area, with more than 135 hm2 each in 2022. The present varieties can basically meet the early-maturation demand in the ample area. In the tightly balanced and constraint areas, however, the growth period of these varieties is too long. To expand the production and efficiency of rapeseed industry, it is urgently needed to strengthen the policy and financial security in the future, carry out joint breeding projects for short-growth-period winter rapeseed varieties to further improve the yield in the ample area and shorten the growth period in the tightly balanced and constrained areas. Meanwhile, to strengthen the research and promotion of supporting cultivation technology for elite varieties, match well early rice, late rice, and rapeseed varieties are also good measures to support the expansion of rapeseed production in the “rice-rice-rapeseed” production area. In addition, improving agricultural socialized services, expanding agricultural insurance and increasing subsidies for rapeseed planting to ensure production benefit will enhance the farmers’ enthusiasm for the “rice-rice-rapeseed” production.

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    Function Analysis of the Soybean Transcription Factor NAC1 in Tolerance to Low Phosphorus
    XIONG ChuWen, GUO ZhiBin, ZHOU QiangHua, CHENG YanBo, MA QiBin, CAI ZhanDong, NIAN Hai
    Scientia Agricultura Sinica    2024, 57 (3): 442-453.   DOI: 10.3864/j.issn.0578-1752.2024.03.002
    Abstract229)   HTML21)    PDF (2288KB)(120)       Save

    【Objective】The productivity of acid soil crops is severely impacted by the limited availability of phosphorus. Soybean (Glycine max) is an important grain and oil crop, known for its preference for phosphorus. Phosphorus deficiency significantly affect both the yield and quality of soybean. While the NAC (NAM, ATAF1/2, CUC2) transcription factor family has been recognized for its involvement in regulating plant responses to various biotic and abiotic stresses, its role in soybean under low phosphorus stress remains largely unexplored. In this study, we focused on the low-phosphorus-tolerant wild soybean variety BW69 as our material, with the objective of cloning and analyzing the expression patterns and functions of the low-phosphorus-tolerant gene GsNAC1. This investigation lays the foundation for a deeper understanding the mechanisms behind the regulation of GsNAC1 response to low phosphorus stress. 【Method】The full-length sequence of GsNAC1 was cloned from BW69, and the characteristics of its encoded amino acid sequence were explored by bioinformatics analysis. In addition, the tissue expression patterns of GsNAC1 were examined through quantitative real-time PCR (qRT-PCR). The subcellular localization of GsNAC1 was observed using laser confocal microscopy. Furthermore, soybean genetic transformation experiments were conducted for further phenotype analysis, and RNA-seq analysis was performed to identify differentially expressed genes (DEGs) related to low phosphorus stress. 【Result】The GsNAC1 gene was successfully cloned, with a full-length coding region of 876 bp. Phylogenetic analysis showed a 62.46% sequence similarity between GsNAC1 and AtATAF1, and no difference was observed with the GmNAC1 sequence from the Williams 82 reference genome. Subcellular localization experiments further revealed that GsNAC1 was localized in the nucleus. Using qRT-PCR, it was discovered that GsNAC1 is expressed in roots, stems, leaves, apes, flowers and pods, with the highest relative expression level found in the roots. Notably, GsNAC1 exhibited significant upregulation in response to low pH and low phosphorus conditions. To assess the phenotypic effects, we performed experiments using both hydroponic and soil cultivation methods under low phosphorus conditions. The transgenic lines showed notable increases in root/shoot ratio, total root length, root surface area, root volume, and phosphorus content compared to the wild type (WT). Transcriptome analysis revealed that GsNAC1 may enhance tolerance to low phosphorus stress by promoting the expression of genes such as GmALMT6, GmALMT27, GmPAP27, and GmWRKY21. 【Conclusion】The expression of GsNAC1 was up-regulated by low pH and low phosphorus, and overexpression of GsNAC1 significantly enhanced the tolerance to low phosphorus stress in soybean, playing a promoting role in the response to low phosphorus stress. Besides, GsNAC1 may enhance the tolerance to low phosphorus stress in soybean by regulating the expression of downstream genes.

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    Spatial-Temporal Variation Characteristics of Wheat and Maize Stalk Resources and Chemical Fertilizer Reduction Potential of Returning to Farmland in Recent 30 Years in China
    LIU ShuJun, LI DongChu, HUANG Jing, QU XiaoLin, MA ChangBao, WANG HuiYing, YU ZiKun, ZHANG Lu, HAN TianFu, LIU KaiLou, SHEN Zhe, ZHANG HuiMin
    Scientia Agricultura Sinica    2023, 56 (16): 3140-3155.   DOI: 10.3864/j.issn.0578-1752.2023.16.008
    Abstract229)   HTML22)    PDF (1219KB)(447)       Save

    【Objective】China has rich wheat and maize stalk resources. It is necessary to clarify the spatial-temporal characteristics of the wheat and maize stalk resources, the corresponding nutrient resources and chemical fertilizer reduction potential through stalk incorporation, which can provide decision basis for promoting the utilization of stalk resources and reducing chemical fertilizer application. 【Method】Based on the soil long-term monitoring data of the Ministry of Agriculture and Rural Affairs in wheat and maize planting areas of China from 1988 to 2019, this study analyzed the amount of wheat and maize stalk and its nutrient resources and fertilizer reduction potential through stalk incorporation in different years in each region of China. 【Result】The annual average amount of wheat and maize stalk resources reached 1.62×108 t and 4.23×108 t, respectively in 2010s, which were increased by 0.16×108 t and 2.04×108 t compared with 1990s, respectively. The annual average amount of wheat and maize stalk NPK resources reached 278.19×104 t and 901.08×104 t, respectively, which were increased by 27.97×104 t and 434.82×104 t compared with 1990s, respectively. Both of them increased most in North China (NC). The annual average amount of wheat stalk resources and NPK resources decreased first and then increased with planting years, while maize increased. In the first stage (1990s to 2000s) and the second stage (2000s to 2010s), the annual variation rate (AVR) of wheat stalk resources were -42.47×104 t·a-1 and 205.10×104 t·a-1, and the AVR of nutrient resources were -0.26×104 t·a-1 of N, -0.03×104 t·a-1 of P, -0.44×104 t·a-1 of K and 1.27×104 t·a-1 of N, 0.14×104 t·a-1 of P, and 2.11×104 t·a-1 of K, respectively. In the first stage and the second stage, the AVR of maize stalk resources were 397.82×104 t·a-1 and 1 643.60×104 t·a-1, and the AVR of nutrient resources were 3.46×104 t·a-1 of N, 0.56×104 t·a-1 of P, 4.46×104 t·a-1 of K and 14.30×104 t·a-1 of N, 2.30×104 t·a-1 of P, and 18.41×104 t·a-1 of K, respectively. There were more than 80% of wheat stalk and its nutrient resources distributed in NC and Middle and lower reaches of Yangtze River (MLRYR), with the highest in NC (0.93×108 t, 160.31×104 t of NPK), and the lowest in Southwest China (SW) (0.09×108 t, 16.05×104 t of NPK). About 70% of maize stalk and its nutrient resources were distributed in Northeast China (NE) and NC, with the highest in NE (1.39×108 t, 296.96×104 t of NPK), and the lowest in MLRYR (0.21×108 t, 44.40×104 t of NPK). The annual average nutrient-release amount of wheat stalk incorporation per unit area were 21.1 kg·hm-2 of N, 3.0 kg·hm-2 of P and 62.3 kg·hm-2 of K in China, with the highest in NC, and the lowest in SW. The annual average nutrient-release amount of maize stalk incorporation per unit area were 48.6 kg·hm-2 of N, 10.6 kg·hm-2 of P and 97.7 kg·hm-2 of K in China, with the highest in Northwest China (NW), and the lowest in SW. The annual average nutrient-release amount of wheat and maize stalk incorporation per unit area increased continually during 1988-2019. The proportion of wheat stalk returning nutrients to the annual chemical fertilizer application were 9.13%-10.82%, 4.26%-6.43% and 88.02%-111.86%, respectively, and that of maize stalk were 22.99%-24.37%, 16.04%-28.67% and 150.29%-171.95%, respectively. 【Conclusion】In general, using wheat and maize stalk properly could satisfy the basic potassium requirement for crop production and reduce the application of about 10%-20% nitrogen fertilizer and 5%-20% phosphorus fertilizer. Making full use of stalk resources was an important guarantee for reducing fertilizer application and increasing efficiency.

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    Spatial-Temporal Variations of High Temperature During Flowering Period in Maize-Producing Areas of China Under Climate Change
    FU ZhenZhen, ZHU GuangXin, LIU ZhiJuan, GUO ShiBo, LI E, YANG XiaoGuang
    Scientia Agricultura Sinica    2023, 56 (14): 2686-2700.   DOI: 10.3864/j.issn.0578-1752.2023.014.005
    Abstract226)   HTML26)    PDF (5588KB)(217)       Save

    【Objective】Under the background of global warming, the frequent occurrence of extreme high temperature would threaten crop production greatly. Therefore, the spatial-temporal variations of high temperature during crop growth period based on several heat stress index were cleared, which was crucial for developing effective disaster risk management and adaptation measures. 【Method】In this study, the maize potential planting area was focused on. Based on the daily maximum temperature data from 1981 to 2060 in two Shared Socioeconomic Pathways scenarios (SSP1-2.6 and SSP5-8.5) of Coupled Model Intercomparison Project Phase 6 (CMIP6) and maize phenology data, we analyzed the spatial distribution and temporal trend of the heat stress intensity (HSI), accumulated heat stress days (AHSD), and heat degree-days (HDD) during flowering period of maize in the baseline period (1981-2014) and future period (2015-2060).【Result】From 1981 to 2014, the HSI, AHSD and HDD during the flowering period of maize were the largest in Huang-Huai-Hai (HHH) and Northwest China (NWC), with the average value of 32.3 and 33.8 ℃, 8.4 and 9.8 d, 22.9 and 40.3 ℃·d, respectively. Due to climate warming, the high temperature during the flowering period of maize in China was characterized by long duration and wide range under the two climate scenarios, especially in SSP5-8.5. The largest temporal trend of HSI and AHSD occurred in Northern China (NC), under SSP1-2.6 and SSP5-8.5. The increasing trend of HSI were 0.97 and 1.16 ℃·(10a)-1, and the increasing trend of AHSD were 0.73 and 1.11 d·(10a)-1. The largest temporal trend of HDD occurred in HHH, under SSP1-2.6 and SSP5-8.5, with the increasing trend of 2.68 and 5.26 ℃·d·(10a)-1. 【Conclusion】In the future, the high temperature during the flowering period of maize in China was characterized by long duration and wide range, especially for HHH and NC. The former was mainly due to the high base temperature, and the latter was due to the large warming trend. The loss caused by high temperature could be reduced by selecting high temperature resistant varieties, adjusting the sowing window, adopting water, fertilizer, and chemical management measures.

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