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A critical review on the principles and procedures for cultivar development and evaluation YAN Weikai Acta Agronomica Sinica    2022, 48 (9): 2137-2154.   DOI: 10.3724/SP.J.1006.2022.11105 Abstract （651）   HTML （41）    PDF（pc） （890KB）（1007）       Knowledge map    Save Plant breeding plays an indispensable role in meeting the increasing need for food and comfort of the mankind in a changing climate. Numerous concepts and procedures aiming at improving breeding efficiency have been put forward, such as various strategies for dealing with genotype by environment interaction, stability analyses, mega-environment analyses, experimental designs and analyses, biplot analyses, and selection indices. In addition, genomic selection has evolved into a stage that plant breeders must consider and cannot ignore. It is of practical importance to understand the relationships among these concepts and procedures, their usefulness, drawbacks, and pitfalls, as well as their place in the theoretical framework of plant breeding and genotype evaluation. Based primarily on personal research and experience, this article attempted to develop a systematic narrative on the principles, key concepts, and analytic procedures related to cultivar development and evaluation, with demonstrations using real-world data. Table and Figures | Reference | Related Articles | Metrics

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Research progress of photosynthetic physiological mechanism and approaches to application in dense planting maize GUO Yao, CHAI Qiang, YIN Wen, FAN Hong Acta Agronomica Sinica    2022, 48 (8): 1871-1883.   DOI: 10.3724/SP.J.1006.2022.13024 Abstract （735）   HTML （76）    PDF（pc） （767KB）（979）       Knowledge map    Save To ensure enough crop production of limited land area is important to food security. The key to solve this issue is to increase yield per unit area. Dense planting is an effective agronomic management practice to increase yield per unit area, photosynthetic rate would not be decreased or even improved by increasing planting density moderately, and then enhancing the yield per unit area. It is a key research focus on revealing the mechanism of photosynthetic physiology for improving yield per unit area by dense planting condition of maize. Dense planting would lead to change photosynthetic characteristics, so controlling the physiological factors that restricts photosynthesis is essential for increasing yield. Tap the photosynthetic physiologic potential for maize condition is physiological basis to ensure yield, which plays an important role in addressing food security issues. Therefore, this review focuses on the changes of the research methods and ideas in photosynthetic physiology, and the research status of the photosynthetic physiological response of maize adapted to dense planting and related agronomic regulation pathways at home and abroad, based on previous research results, so as to provide the theoretical and technical methods basis for photosynthetic physiology research. Based on the development trend of modern technology, it is believed that tapping photosynthetic potential and narrowing the gap between photosynthetic potential and actual photosynthetic efficiency are still the main goals of maize dense planting research by traditional research methods combined with molecular biology techniques in the future. In further study, research emphasis should be to investigate the responses of differential expression of photosynthetic physiological function genes to cultivation measures, clarifying the relationship and interaction between agronomic management practice and information expression of photosynthetic-related genes in densely planted maize, enhancing photosynthetic potential for maize via agronomic management practice and molecular biology technology, in order to provide photosynthetic physiological theory and practice to support for maize dense planting. Table and Figures | Reference | Related Articles | Metrics

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Heat-inducible transcription factor ZmNF-YC13 regulates heat stress response genes to improve heat tolerance in maize MEI Xiu-Peng, ZHAO Zi-Kun, JIA Xin-Yao, BAI Yang, LI Mei, GAN Yu-Ling, YANG Qiu-Yue, CAI Yi-Lin Acta Agronomica Sinica    2023, 49 (7): 1747-1757.   DOI: 10.3724/SP.J.1006.2023.23054 Abstract （397）   HTML （60）    PDF（pc） （2878KB）（973）       Knowledge map    Save Heat stress is an essential factor affecting maize growth and yield formation. The exploration and mechanism analysis of related tolerance genes is an important field for breeding maize heat stress tolerant varieties. However, there is few study in this aspect. In this study, we identified a nuclear factor ZmNF-YC13 associated with heat stress response, and its encoding gene expression was rapidly induced by high temperature and osmotic stress. The promoter of Arabidopsis thaliana heat stress-inducible expression gene AtHSP70 was used to drive ZmNF-YC13 and the heat-inducible expression maize material of ZmNF-YC13 (HSP21Pro:ZmNF-YC13-myc) was successfully screened. Phenotypic analysis after high temperature treatment demonstrated that leaf length, leaf width, shoot thickness, fresh and dry weight of shoot and root were significantly higher than wild type. The relative expression level showed that ZmNF-YC13 could enhance the inducible level of downstream heat stress response genes in response to heat stress. Luciferase reporter assay and ChIP-qPCR assay also revealed that ZmNF-YC13 could regulate the expression of heat stress transcription factor ZmHsfA2c. These results confirmed preliminarily that ZmNF-YC13 could improve the heat tolerance of maize by regulating downstream heat stress response genes, which could provide a theoretical basis for marker-assisted selection and germplasm identification using the polymorphism of this locus. Table and Figures | Reference | Related Articles | Metrics

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Genome-wide association analysis and candidate gene selection of yield related traits in rice YANG Fei, ZHANG Zheng-Feng, NAN Bo, XIAO Ben-Ze Acta Agronomica Sinica    2022, 48 (7): 1813-1821.   DOI: 10.3724/SP.J.1006.2022.12047 Abstract （581）   HTML （39）    PDF（pc） （4541KB）（972）       Knowledge map    Save Rice is the most important food crop for more than half of the world’s population, and the cultivation of rice varieties with high and stable yield is crucial for solving the world’s food problems. In this study, 226 rice core materials with relatively consistent growth stage were selected from “3K Rice Genome Project” and 2429 kb of high density genotype and 10 agronomic traits including growth period, plant height, effective panicle number, panicle length, spikelet density, seed setting rate, thousand-grains weight, yield per plant, spikelet per panicle, and grains per panicle were investigated by genome-wide associate study combined with 2429 kb of high-density genotype data. A total of 43 loci significantly associated with main agronomic traits were identified, including seven known loci, such as qRGP7.2, qPH12, qPL6.2, qSD6.2, qTGW1.1, qGP1, and qGP5.2. Six candidate genes were screened out, including LOC_Os12g18760 related to plant height, LOC_Os03g33530 related to effective panicle number, LOC_Os06g30940 related to panicle length, LOC_Os01g49810 related to thousand grains weight, LOC_Os09g25260 related to yield per plant, and LOC_Os09g32620 related to spikelet density and spikelet per panicle. These results provide important gene resources and the theoretical reference for genetic improvement of rice yield. Table and Figures | Reference | Related Articles | Metrics

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Research progress on physiological ecology and genetic basis of rice plant architecture XU Na, XU Quan, XU Zheng-Jin, CHEN Wen-Fu Acta Agronomica Sinica    2023, 49 (7): 1735-1746.   DOI: 10.3724/SP.J.1006.2023.22050 Abstract （639）   HTML （98）    PDF（pc） （5416KB）（945）       Knowledge map    Save Rice is one of the most important crops in China and even the world. Plant type is an important agronomic trait of rice, which is closely related to yield, quality, and stress resistance. Plant type improvement has played an important role in rice breeding in the past, and will have a profound impact on rice breeding in the future. On the base of related achievements of Rice Research Institute of Shenyang Agricultural University, this paper comprehensively reviewed the research progress of rice plant type from the aspects of the concept of plant type, physiological ecology, and genetic basis of plant type breeding, and also discussed the existing problems and development direction of rice plant type. With the application of the latest research results of modern molecular biology, analyze the relationship between various organs and their optimal combination among population and individual, define the physiological ecology basis and the molecular regulatory network, and apply to plant type breeding practice, which is expected to achieve a higher level of “ideal plant type breeding” of rice. Table and Figures | Reference | Related Articles | Metrics

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Research progress on the formation of large panicles in rice and its regulation LIU Li-Jun, ZHOU Shen-Qi, LIU Kun, ZHANG Wei-Yang, YANG Jian-Chang Acta Agronomica Sinica    2023, 49 (3): 585-596.   DOI: 10.3724/SP.J.1006.2023.22035 Abstract （809）   HTML （86）    PDF（pc） （796KB）（938）       Knowledge map    Save The spikelet number per panicle is a key factor that constitutes the grain yield in rice. Modern high-yielding rice varieties mostly show high spikelet number per panicle. Increasing the spikelet number per panicle and promoting the formation of large panicles are important ways to improve rice yield. This paper reviewed the relationship between the formation of spikelet number per panicle and young panicle development in rice. Combined with the author’s related research, the mechanisms underlying genetic regulation in rice panicle size, the effects of nutritional status and nitrogen fertilizer management, water, temperature, light, and endogenous hormones on the formation of spikelet number per panicle in rice were reviewed. We put forward the future research focus on strengthening the formation of large panicles in rice from the aspects of root morphophysiology and young panicle development, water and nitrogen management, temperature and light conditions, and the physiological and molecular mechanisms of interaction between plant hormones regulating spikelet degeneration. The purpose of this study was to provide a basis for the selection and cultivation of high-yielding rice varieties with large panicles. Table and Figures | Reference | Related Articles | Metrics

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Genome-wide identification and expression analysis of BBX gene family in potato ( Solanum tuberosum L.) MA Wen-Jing, LIU Zhen, LI Zhi-Tao, ZHU Jin-Yong, LI Hong-Yang, CHEN Li-Min, SHI Tian-Bin, ZHANG Jun-Lian, LIU Yu-Hui Acta Agronomica Sinica    2022, 48 (11): 2797-2812.   DOI: 10.3724/SP.J.1006.2022.14199 Abstract （416）   HTML （32）    PDF（pc） （10466KB）（925）       Knowledge map    Save The B-box (BBX) gene family is a type of zinc finger protein transcription factor that plays an important role in the growth and development of plants. In this study, 30 potato BBXs family members (StBBXs) were identified, and their physical and chemical properties, chromosomal location, gene structure, protein conserved domains, gene repetition events, expression patterns, and protein interaction network were analyzed. The results showed that 30 StBBXs were unevenly distributed on 11 chromosomes. According to their gene structures and phylogenetic characteristics, 30 StBBXs were divided into 5 subclasses. Collinearity analysis indicated that there were 15 pairs BBX genes which were orthologous to potato (Solanum tuberosum) and Arabidopsis. We analyzed the relative expression profiles of StBBX genes in different tissues of double haploid (DM) potato, as well as under abiotic stresses and hormone treatments by RNA-seq downloaded from the PGSC (Potato Genome Sequencing Consortium) database. In addition, to explore the relative expression patterns of the StBBX genes in these tissues, we performed RNA-seq on the tuber skin and flesh of three potato varieties with different colors and analyzed their correlations with the expression of key genes for anthocyanin synthesis. Furthermore, the protein interaction network of StBBXs which differentially expressed in color tuber tissues was constructed using String database. These results provide a theoretical basis for further understanding the StBBX gene family, further function of StBBX genes in abiotic stress tolerance and anthocyanin biosynthesis in potato, and StBBX genes in potato might be related to abiotic stress responses and anthocyanin biosynthesis. Table and Figures | Reference | Related Articles | Metrics

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Construction of evaluation method for tolerance to high-temperature and screening of heat-tolerant germplasm resources of bud stage in soybean LI Jia-Jia, LONG Qun, ZHU Shang-Shang, SHAN Ya-Jing, WU Mei-Yan, LU Yun, ZHI Xian-Guan, LIAO Wei, CHEN Hao-Ran, ZHAO Zhen-Bang, MIAO Long, GAO Hui-Hui, LI Ying-Hui, WANG Xiao-Bo, QIU Li-Juan Acta Agronomica Sinica    2023, 49 (11): 2863-2875.   DOI: 10.3724/SP.J.1006.2023.34025 Abstract （465）   HTML （54）    PDF（pc） （530KB）（866）       Knowledge map    Save The frequent occurrence of extreme high temperature (HT) events causes continuous heat damage to soybean production, which seriously damages the yield components and quality traits. The seeds are sensitive to the changes of the external environment at germination stage. The rising temperature and the accompanying drought will affect the emergence of soybean seeds. The establishment of a set of scientific evaluation methods for HT tolerance at bud stage can provide a theoretical basis for the early identification of soybean, the breeding of HT tolerance germplasm, and the study of tolerance mechanism. In this study, 385 germplasm resources varieties were selected as the experimental materials, which creating a HT environment by artificial climate incubator and subjected to HT-stress for 3 d (40℃, 16 h light /8 h darkness) at bud stage of soybean. Compared with the control (25℃, 16 h light /8 h darkness), the hypocotyl length of soybean bud stage was significantly decreased 10.9% under HT stress (P < 0.05). The indices of fresh root weight, dry root weight, and root-shoot ratio increased by 13.10%, 22.20%, and 16.90%, respectively (P<0.01). The results showed that HT-stress significantly affected the surface and underground biomass distribution of bud stage in soybean. Meanwhile, the principal component analysis for the coefficient of HT-tolerance for each trait converted 11 indexes into two principal component factors. The comprehensive evaluation value (H-value) of soybean response to HT-stress was obtained by the standardized analysis of membership function, and cluster analysis was conducted for the tested varieties based on H-value. Ultimately, 385 germplasm resources were divided into 5 grades for the HT-tolerance at bud stage in soybean [namely: Grade I (tolerance), Grade II (strong tolerance), Grade III (medium), Grade IV (strong sensitive), and Grade V (sensitive type)] and four HT-resistant varieties based on the specific performance (H245, H070, H268, and H216) were initially selected combined with the actual heat resistance performance. After the stepwise regression analysis of each index, a predictive model for the comprehensive evaluation of HT tolerance (H-value) at bud stage of soybean was established: H = 0.191 + 0.017X1 - 0.007X2 + 0.013X7 + 0.027X8 - 0.009X10 (R2=0.9752). Five indexes main including hypocotyl length (X1), main root length (X2), hypocotyl dry weight (X7), root fresh weight (X8), and simplified vigor index (X10) were screened out as the evaluation indexes for HT tolerance at bud stage in soybean. Table and Figures | Reference | Related Articles | Metrics

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Research progress of seed dormancy and germination regulation SONG Song-Quan, TANG Cui-Fang, LEI Hua-Ping, JIANG Xiao-Cheng, WANG Wei-Qing, CHENG Hong-Yan Acta Agronomica Sinica    2024, 50 (1): 1-15.   DOI: 10.3724/SP.J.1006.2024.34012 Abstract （768）   HTML （120）    PDF（pc） （3074KB）（864）       Knowledge map    Save Dormancy enables plant seeds to time germination until environmental conditions become favorable for seedling survival and growth. The dormancy characteristics of seeds are of important ecological adaptive significance and notable agricultural value. Phytohormone abscisic acid (ABA) and gibberellin (GA) are the key factors for seed dormancy and germination. Mature seeds in dormancy state contain high levels of ABA and low levels of GA. ABA induces and maintains seed dormancy, while GA antagonizes ABA and promotes seed germination. DELAY OF GERMINATION-1 (DOG1) is a major regulator of seed dormancy and had a synergistic effect with ABA to delay germination. DOG1 enhances ABA signal transduction by combining with PP2C ABA hypersensitive germination (AHG1/AHG3), and inhibits the action of AHG1 to increase ABA sensitivity and impose seed dormancy. Imprinted genes are regulated by epigenetic mechanisms before and after fertilization, and are closely related to the establishment and release of seed dormancy. In recent years, remarkable progress has been made in the regulation of seed dormancy. In the present paper, we reviewed the effects of phytohormones ABA and GA on seed dormancy and germination, the action mechanism regulating seed dormancy by DOG1, and the epigenetic regulation of seed dormancy and germination. In addition, we also propose some scientific issues that need to be further investigated in this field to provide some information for understanding the molecular mechanism of seed dormancy and germination, breeding in anti-preharvest sprouting in crop plants, and promoting the germination of dormant seeds. Table and Figures | Reference | Related Articles | Metrics

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Contents and compositions of amino acids in rice grains and their regulation: a review YANG Jian-Chang, LI Chao-Qing, JIANG Yi Acta Agronomica Sinica    2022, 48 (5): 1037-1050.   DOI: 10.3724/SP.J.1006.2022.12062 Abstract （817）   HTML （68）    PDF（pc） （658KB）（819）       Knowledge map    Save Amino acids in cereal grains are important nutrients for both human and animals. Increasing the content of amino acids in the rice grain, especially lysine and other essential amino acids, plays a very important role in improving the nutritional standard of people in the countries with rice as staple food. This paper reviewed some research progresses in the contents and compositions of amino acids in the mature grain of rice and their distribution in the different parts of a grain, the synthesis and metabolism of amino acids in the grain, the role of plant hormones in regulating the synthesis and metabolism of on amino acids, and the effects of environmental factors and cultivation practices on the contents and compositions of amino acids in the grain, and discussed the existing problems and key points for future research. It merits further investigating the temporal (at different filling stages) and spatial (at different parts of a grain) distribution characteristics of the contents and compositions of amino acids in a grain during the filling, their physiological and biochemical mechanism, and cultivation regulation and its principle. Such a study is expected to gain new insight into the mechanism in the formation and distributions of amino acids in a rice grain, and explore a new way to increase the contents of amino acids, especially essential amino acids such as lysine, in milled rice. Table and Figures | Reference | Related Articles | Metrics

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Genetic basis analysis of high-yielding in Yannong wheat varieties WANG Hao, SUN Ni-Na, WANG Chu, XIAO Lu-Ning, XIAO Bei, LI Dong, LIU Jie, QIN Ran, WU Yong-Zhen, SUN Han, ZHAO Chun-Hua, LI Lin-Zhi, CUI Fa, LIU Wei Acta Agronomica Sinica    2023, 49 (6): 1584-1600.   DOI: 10.3724/SP.J.1006.2023.21033 Abstract （368）   HTML （23）    PDF（pc） （3125KB）（813）       Knowledge map    Save The Yannong series wheat has the characteristics of high yield potential, disease resistance, and wide adaptability. Yannong 1212, a high-yield and multi-resistant variety approved in recent years, has repeatedly broken the national winter wheat yield record for many times. To date, the numerous varieties derived from Yannong series have been released. Lumai 14 has derived from at least 214 wheat authorized varieties and become an important backbone parent by 2020. This objective of the study is to characterize genetic basis of high yielding potential in Yannong series, identify the key chromosomal segments of high yield and wide adaptability, and provide theoretical reference for the genetic improvement of new wheat varieties. The genotype of 38 Yannong series wheat varieties, some of their derived varieties, and 244 authorized varieties (advanced lines) were scanned by wheat 55K SNP array, and the environmental phenotypes were identified. Phenotype evaluation of yield-related traits of the natural mapping population was conducted in multiple environments. The genetic effects of the common high-frequency co-selected genetic segment (HFCS) of Yannong series varieties were characterized in detail based on the genotypes of wheat 55K SNP array. In addition, the HFCS from Lumai 14 to its derived varieties were also specified. The genetic basis of high yield potential in Yannong 1212 and Lumai 14 were revealed at the whole genome-wide level. The genetic similarity coefficients among the 17 Yannong series authorized varieties ranged from 0.80 to 0.99. Based on genotyping data from the 55K SNP array in the 17 Yannong series authorized varieties, 975 HFCS were obtained, and their segments lengths ranged from 1.00 Mb to 75.18 Mb. Most HFCS were distributed on chromosomes 2D, 4D, 6D, and 7B, with the total length accounting for more than 40% of the corresponding chromosomes, respectively. The genetic contribution rate of Lumai 14 to its 23 derived varieties was approximately 71.45% on average at the genome level, with A, B, and D of 69.63%, 66.04%, and 79.82%, respectively. A total of 430 high-frequency transmission genetic segments (HFTGS) 14 were detected in Lumai derived progency and 265 blocks (61.6%) overlapped with the HFSC in the Yannong series. Lumai 14 was a backbone parents and Yannong 1212 was a novel authorized varieties with high yield potential and wide adaptability. To characterize their genetic basis of high yield and wide adaptability, single marker analysis based on the natural population was performed. The results showed that both Lumai 14 and Yannong 1212 had been enriched in excellent alleles for thousand kernel weight (TKW) and yield per plant (YPP). Approximately 92.3% and 84.4% of the significant loci in the HFTGS of Lumai 14 were shown to increase TKW and YPP, mainly distributing on chromosomes 2A, 2B, 2D, 4A, 5B, 6A, and 7A. Yannong series authorized wheat varieties had enriched in excellent alleles of yield-related genes and QTLs especially for TKW and YPP, which played a key role to their high and stable yielding potential. Table and Figures | Reference | Related Articles | Metrics

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Identification of abiotic stress-related gene co-expression networks in maize by WGCNA DENG Zhao, JIANG Huan-Qi, CHENG Li-Sha, LIU Rui, HUANG Min, LI Man-Fei, DU He-Wei Acta Agronomica Sinica    2023, 49 (3): 672-686.   DOI: 10.3724/SP.J.1006.2023.23017 Abstract （422）   HTML （33）    PDF（pc） （2789KB）（749）       Knowledge map    Save Weighted Gene Co-expression Network Analysis (WGCNA) is a classic systems biology analysis method, which can be used to identify coexpressed gene modules and explore the biological correlation between modules and target traits, and mine core genes in module networks. In this study, 58 transcriptome data of roots, stems, leaves, and other tissues under low temperature stress, high temperature stress, drought stress, and salt stress in maize (Zea mays L.) were collected, and the gene co-expression network of maize abiotic stress was identified by WGCNA method. After filtering the 12,552 low-expression genes from transcriptome data, the co-expression network was constructed using the remaining 27,204 high-expression genes, and 25 modules were obtained. According to the distribution of abiotic stress-related genes and different expression genes in the modules reported in maize, the mediumpurple4, ivory, coral2, darkseagreen4 modules most related to low temperature stress, high temperature stress, drought and salt stresses, and green modules responding to various stresses were screened out. Subsequently, GO enrichment of the genes in these five modules revealed that genes with functions related to abiotic stress were significantly enriched in these modules, such as stress response, peroxidase activity. Correlation analysis showed that 10 abiotic stress-related core genes were predicted, including Zm00001eb072870, Zm00001eb320970, Zm00001eb037640, Zm00001eb423300, and Zm00001eb265310. This study provides new ideas for the mining of abiotic stress-related genes and the research of abiotic stress regulatory networks in maize. Table and Figures | Reference | Related Articles | Metrics

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Evaluation on concentration and nutrition of micro-elements in wheat grains in major wheat production regions of China CHU Hong-Xin, MU Wen-Yan, DANG Hai-Yan, WANG Tao, SUN Rui-Qing, HOU Sai-Bin, HUANG Ting-Miao, HUANG Qian-Nan, SHI Mei, WANG Zhao-Hui Acta Agronomica Sinica    2022, 48 (11): 2853-2865.   DOI: 10.3724/SP.J.1006.2022.11099 Abstract （615）   HTML （28）    PDF（pc） （762KB）（708）       Knowledge map    Save Wheat is a kind of staple food crop, and an important source for carbohydrates and microelement for human health. Therefore, it is of great significance to clarify the micronutrient concentration and nutritional status of wheat grain in the major wheat production regions in China, for the purpose of optimizing wheat micronutrient management and maintaining human health. Totally, 1112 wheat and soil samples were collected from 17 major wheat production provinces in China during 2016 to 2020. Microelement concentrations of the samples were determined and nutritional status was evaluated by comparison with the acceptable daily intake value (ADI) according to the human micronutrient intake standard of Chinese Nutrition Society and health risk assessment method of United States Environmental Protection Agency, as well as the dietary habit of Chinese residents. Results showed that the average grain iron (Fe) concentration of wheat in China was 43.8 mg kg-1 when 72.9% of the samples of Fe concentration was under the lower Fe limit of 50 mg kg-1, and all the samples were under the upper limit of 140 mg kg-1. The average grain manganese (Mn) concentration was 43.0 mg kg-1 when only 4.1% of samples were under the lower limit of 22 mg kg-1 and 23.7% of samples were above the upper limit of 50 mg kg-1. The average grain copper (Cu) concentration was 4.6 mg kg-1 when 7.6% of samples were under the lower limit of 3 mg kg-1 and no sample was above the upper limit of 10 mg kg-1. The average grain zinc (Zn) concentration was 31.4 mg kg-1 when 85.8% of samples were under the lower limit of 40 mg kg-1 and only 4.1% was above the upper limit of 50 mg kg-1. The average grain boron (B) concentration was 1.2 mg kg-1 when 29.2% of samples was under the lower limit of 0.8 mg kg-1 and no sample was above the upper limit of 10 mg kg-1. The average grain molybdenum (Mo) concentration was 0.5 mg kg-1 when 18.8% of samples were under the lower limit of 0.2 mg kg-1 and only 0.4% of samples was above the upper limit of 2 mg kg-1. There were regional variations in the contents of wheat grain micronutrient in major wheat production regions in China, among which the contents of Fe and Zn were generally low in most regions, and the contents of B and Mo were insufficient in some areas, while the content of Mn was high, and the content of Cu was basically in the recommended concentration ranges. Table and Figures | Reference | Related Articles | Metrics

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Effects of nutrient uptake and utilization on yield of maize-legume strip intercropping system YANG Huan, ZHOU Ying, CHEN Ping, DU Qing, ZHENG Ben-Chuan, PU Tian, WEN Jing, YANG Wen-Yu, YONG Tai-Wen Acta Agronomica Sinica    2022, 48 (6): 1476-1487.   DOI: 10.3724/SP.J.1006.2022.13017 Abstract （565）   HTML （32）    PDF（pc） （1677KB）（696）       Knowledge map    Save To clarify the difference of nutrient uptake and utilization to yield advantage between maize-soybean relay intercropping and maize-peanut intercropping, we conducted a field experiment for two consecutive years. The results were obtained by comparing nitrogen (N), phosphorous (P), and potassium (K) absorption efficiency and utilization in the intercropping with sole cropping. The results showed that land equivalent ratio (LER) of maize-soybean relay intercropping was 1.16-1.72, which had the advantage of intercropping yield, but the LER of maize-peanut intercropping was 0.89-1.13, which had no obvious yield disadvantage. In maize-soybean relay intercropping system, the amount of N, P, and K uptake was higher than that of the corresponding sole cropping by 32.60%-54.22%, 27.35%-34.64, and 17.74%-24.42%, respectively, but the N utilization efficiency was lower by 21.99%-42.07%. The contributions of the N, P, and K uptake efficiencies to LER were 0.34-0.62, 0.31-0.46, and 0.22-0.32, and the utilization efficiencies contributions were -0.11 to -0.35, -0.03 to -0.31, and -0.11 to 0.22, respectively. In maize-peanut intercropping system, the amount of N, P, and K uptake was higher than that of the corresponding sole cropping by -7.86% to 31.58%, 23.09%-46.52%, and 1.60%-55.48%, respectively, and the N utilization efficiency was higher by 7.55-26.60. The contributions of the N, P and K uptake efficiencies to LER were 0-0.22, 0.05-0.27, and -0.11-0.32, respectively, and the utilization efficiencies contributions were -0.25-0.19, -0.32-0.11, and -0.47-0.32, respectively. In conclusion, yield advantage of maize-soybean relay intercropping was mainly from enhanced nutrient uptake efficiency, but there was no obvious yield advantage in maize-peanut intercropping mainly due to relatively less contribution of nutrient uptake to yield advantage. Table and Figures | Reference | Related Articles | Metrics

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Identification of regulatory genes related to flavonoids synthesis by weighted gene correlation network analysis in the panicle of foxtail millet HAN Shang-Ling, HUO Yi-Qiong, LI Hui, HAN Hua-Rui, HOU Si-Yu, SUN Zhao-Xia, HAN Yuan-Huai, LI Hong-Ying Acta Agronomica Sinica    2022, 48 (7): 1645-1657.   DOI: 10.3724/SP.J.1006.2022.14107 Abstract （471）   HTML （31）    PDF（pc） （1508KB）（688）       Knowledge map    Save Flavonoids are important secondary metabolites in plants and play significant roles in plant growth and development. They have antioxidant activity and are beneficial to human health. Foxtail millet is rich in nutrients, making it a healthy grain and popular among consumers. The crop is gaining more and more attention as a C4 model plant. However, there are few studies on the metabolic regulatory mechanism of flavonoids in foxtail millet. In this study, the panicles of flavonoid-rich variety JG21 and flavonoid-less variety NMB were analyzed on the flavonoid metabolomic profiles. Transcriptome sequencing was performed on the panicles of JG21 at different developmental stages. Transcription factors involved in regulating flavonoid metabolism were identified by weighted gene correlation network analysis (WGCNA). The expression patterns of these genes were verified by qRT-PCR. The results showed that the main flavonoid components enriched in the spikelets of foxtail millet were apigenin, vitexin, and naringenin, accounting for more than 79% of the total flavonoids. The flavonoid-related network of JG21 contained 38,921 genes, which were divided into 32 modules. Among them, the turquoise module, green module, and magenta module were significantly correlated with flavonoid metabolism. A total of 27 transcription factor families related to the regulation of flavonoid metabolism were identified by using differentially expressed genes related to flavonoid metabolism pathway as the hubs, and 11 transcription factors were obtained through promoter binding motif analysis. Pearson correlation analysis showed that 7 out of the 11 transcription factors might be involved in flavonoid metabolism, which were WRKY38, MYB4a, PI, WRKY15, WRKY62, MYB46, and WRKY23, respectively. The above results provide new candidate genes for studying the transcriptional regulation mechanism of flavonoids and lay a foundation for further investigation of the flavonoid metabolism regulation mechanism in foxtail millet. Table and Figures | Reference | Related Articles | Metrics

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Genetic diversity of wheat breeding parents revealed by 55K SNP-based microarray LU Mao-Ang, PENG Xiao-Ai, ZHANG Ling, WANG Jian-Lai, HE Xian-Fang, ZHU Yu-Lei Acta Agronomica Sinica    2023, 49 (6): 1708-1714.   DOI: 10.3724/SP.J.1006.2023.21047 Abstract （342）   HTML （25）    PDF（pc） （1484KB）（686）       Knowledge map    Save The objective of this study is to identify the genetic diversity among wheat parental materials from different provinces. To reveal the genetic diversity and population structure by using wheat 55K SNP chip, 150 wheat accessions from Anhui, Jiangsu, Henan, Sichuan, and Shandong provinces were analyzed. A total of 52,537 SNP loci were detected in the 150 wheat accessions. 39,422 high quality markers were obtained, of which 38,135 were polymorphic, accounting for 96.74%. The distribution of 38,135 polymorphic markers among the genomes showed the least in D subgenome (10,450), the most in B subgenome (15,290). The average polymorphic information content (PIC) was 0.315, with a variation of 0.068-0.375. The averaged genetic distance of accessions differed based on the origin: Henan > Sichuan > Shandong > Jiangsu > Anhui. The results of cluster analysis, principal component analysis, and population structure analysis were highly consistent, and the clustering results were consistent with the pedigree, regional origin, and breeding group. The study revealed that the average polymorphism information content in each province was at a moderate PIC level, but the average genetic distance of the materials was close. This indicated that the high-quality germplasm resources should still be introduced to alleviate the material homogeneity, so as to increase the ability of wheat to cope with stress and reduce the vulnerability and risk in actual wheat production. Table and Figures | Reference | Related Articles | Metrics

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Current situation, issues, and prospects of breeding and approval of new varieties of nutrition-oriented crops ZHU Da-Zhou, WU Ning, ZHANG Yong, SUN Jun-Mao, CHEN Meng-Shan Acta Agronomica Sinica    2023, 49 (1): 1-11.   DOI: 10.3724/SP.J.1006.2023.23018 Abstract （578）   HTML （60）    PDF（pc） （305KB）（678）       Knowledge map    Save With China’s economic and social development and the continuous improvement of people’s living standards, the consumers’ diet preference has switched from purely pursuing food taste to more nutrition and health demand, resulting in an urgent need for a transformation and upgrading of the current dietary structure to match the new trend. Correspondingly, nutrition and health-oriented crop breeding is imperative. This review aims to elaborate the research progresses in nutrition-oriented crop breeding in the world with the evolving goals of crop breeding in China, to sort out the nutritional quality indicators dominating in crop breeding globally, and to analyze the problems in existing nutritional indicators involved in the approval of new crop varieties in China. In conclusions, nutritional indicators combined with the consumer nutritional demand are put forward to the current examination and verification system of existing and new crop varieties in China and thus to promote the rapid development of crop nutritional breeding and support the nutrition demand of consumers and the construction of “Healthy China” from the source. Table and Figures | Reference | Related Articles | Metrics

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Genetic diversity analysis of Chinese fresh corn hybrids using SNP Chips XIAO Ying-Ni, YU Yong-Tao, XIE Li-Hua, QI Xi-Tao, LI Chun-Yan, WEN Tian-Xiang, LI Gao-Ke, HU Jian-Guang Acta Agronomica Sinica    2022, 48 (6): 1301-1311.   DOI: 10.3724/SP.J.1006.2022.13031 Abstract （685）   HTML （75）    PDF（pc） （5135KB）（669）       Knowledge map    Save China is a major fresh corn production and consumption country in the world. Assessment of genetic diversity and relationships among fresh corn hybrids in China has great benefit for hybrid identification and breed cultivation. In this study, an Illumina Maize 6K chip was employed to perform genome-wide scanning for the population structure and genetic distance of 385 fresh corn hybrids nationwide. The results showed that the average genetic diversity of 5067 SNP markers in 385 fresh corn hybrids was 0.406, with a range of 0.097-0.500. The average polymorphic information content (PIC) was 0.319, with a range of 0.092-0.375. The results of PCA and population genetic structure analysis revealed that the hybrids were mainly divided into three groups, which were non-sweet corn group (185 varieties), temperate sweet corn group (123 varieties), and tropical sweet corn group (77 varieties). The genetic distance between any two hybrids ranged from 0.132 to 0.472, with an average of 0.37. A total of 160 genome regions indicated strong population differentiation among different groups following FST analysis. Four key genes (sh2, su1, su2, and wx1) of starch synthesis pathway in maize grains were detected. Two candidate genes (sh2 and DGAT1-2) demonstrated different selection patterns in fresh corn groups and were validated using molecular markers. These results provide important theoretical guidance for the breeding and improvement of fresh corn varieties in China. Table and Figures | Reference | Related Articles | Metrics

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Research advance on annual water use efficiency of winter wheat-summer maize cropping system in North China Plain ZHANG Jin-Xin, GE Jun-Zhu, MA Wei, DING Zai-Song, WANG Xin-Bing, LI Cong-Feng, ZHOU Bao-Yuan, ZHAO Ming Acta Agronomica Sinica    2023, 49 (4): 879-892.   DOI: 10.3724/SP.J.1006.2023.21034 Abstract （473）   HTML （45）    PDF（pc） （931KB）（668）       Knowledge map    Save Improving water use efficiency without reducing the annual grain yield is the key to promoting the sustainable development of the winter wheat-summer maize cropping system in the North China Plain. Since the middle and late 20th century, many researches have explored ways to improve the annual water use efficiency of winter wheat-summer maize, including development of water-saving irrigation technology, optimizing of irrigation system, establishment of alternative water-saving cropping system, and breeding new variety of water-saving and drought resistant, which significantly improved the crop water use efficiency (WUE). Here, we summarized the research advance on efficient annual water utilization of winter wheat-summer maize cropping system in North China Plain, and proposed a way regulating the annual water balance through using appropriate tillage or sowing/harvest date to improve water use efficiency of winter wheat-summer maize cropping system. It could provide theory and technical support for the establishment of water-saving and high-yield cultivation cropping system of winter wheat-summer maize in the North China Plain. Table and Figures | Reference | Related Articles | Metrics

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Development of functional markers and genotype screening for nitrogen use efficiency genes in rice TAO Ya-Jun, ZHU Jing-Yan, WANG Jun, FAN Fang-Jun, XU Yang, LI Wen-Qi, WANG Fang-Quan, CHEN Zhi-Hui, JIANG Yan-Jie, ZHU Jian-Ping, LI Xia, YANG Jie Acta Agronomica Sinica    2022, 48 (12): 3045-3056.   DOI: 10.3724/SP.J.1006.2022.12080 Abstract （435）   HTML （31）    PDF（pc） （2244KB）（665）       Knowledge map    Save Nitrogen is an essential mineral element that affects plants biomass and yield formation, and its efficient and reasonable utilization is an important guarantee for sustainable agricultural. Breeding rice varieties containing high nitrogen use efficiency (NUE) genes is an effective way to increase NUE and reduce the amount of nitrogen fertilizer. In this study, five genes, OsNR2, OsNPF6.1, OsTCP19, OsLHT1, and OsGRF4, were selected from the aspects of nitrogen absorption, transportation, and assimilation. Based on the reported functional haplotype, co-segregated markers were designed. Using six pairs of allele-specific PCR (AS-PCR) markers and one pair of InDel marker, 70 indica rice, 34 japonica rice, and 84 Taihu rice resources were identified. The results showed that OsNR2 was widely distributed in indica rice, while OsNPF6.1, OsTCP19, and OsGRF4 were less distributed. All 34 japonica rice and 84 Taihu rice resources only contained OsLHT1. We also successfully obtained two indica germplasms, which contained OsNR2, OsNPF6.1, and OsGRF4. The functional markers developed in this research and two materials provide technical support for breeding new rice varieties with high NUE through molecular marker-assisted selection (MAS) methods. Table and Figures | Reference | Related Articles | Metrics

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Molecular mechanisms of somatic embryogenesis in plants HAN Bei, SUN Si-Min, SUN Wei-Nan, YANG Xi-Yan, ZHANG Xian-Long Acta Agronomica Sinica    2023, 49 (2): 299-309.   DOI: 10.3724/SP.J.1006.2023.24103 Abstract （787）   HTML （117）    PDF（pc） （289KB）（642）       Knowledge map    Save Plant cell totipotency refers to that each cell has all the genetic information of the plant, and in vitro tissues or cells has the potential to develop into a whole plant under appropriate culture conditions. Somatic embryogenesis is the most efficient way to reflect the totipotency of plant cells. It has broad application prospects in the fields of artificial seeds, haploid breeding, asexual reproduction, and germplasm preservation, and its mechanism is also a hotspot in basic research. In recent years, with the development of technology and in-depth research, the molecular regulation mechanism of plant somatic embryogenesis has made important progress. Plant somatic embryogenesis is the result of the expression and regulation of a series of genes in spatiotemporal order. In this review, we systematically reviewed the roles of hormones and stress signal transduction, embryonic development related transcription factors, extracellular proteins, and epigenetic regulation in somatic embryogenesis, and prospected future research priorities and directions in this field. Table and Figures | Reference | Related Articles | Metrics

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Genome-wide identification and characterization of MAPK genes and their response to biotic stresses in foxtail millet LIU Jia, ZOU Xiao-Yue, MA Ji-Fang, WANG Yong-Fang, DONG Zhi-Ping, LI Zhi-Yong, BAI Hui Acta Agronomica Sinica    2023, 49 (6): 1480-1495.   DOI: 10.3724/SP.J.1006.2023.24113 Abstract （379）   HTML （48）    PDF（pc） （6746KB）（637）       Knowledge map    Save MAPK plays an important role in plant growth and development regulation, biotic and abiotic stress responses, and hormone signal transduction. In order to elucidate the biological function of the SiMPK genes in foxtail millet, we identified the SiMPK family members in the genome and analyzed the distribution, structure, evolution, and its expression characteristics in response to different stresses. In this study, the SiMPK gene family members were identified in the genome-wide level using the amino acid sequences of conserved domains and specific TXY motifs of MAPK proteins between foxtail millet and rice. The protein physicochemical property, phylogenetic evolution, chromosome distribution, gene structure, protein conserved motif, promoter cis-acting regulatory elements, and collinearity were analyzed. The relative expression patterns of SiMPK genes in the different tissue, under the biotic stresses of Uromyces setariae-italicae Yoshino and Ostrinia furnacalis and with different hormone treatments were analyzed by qRT-PCR. The results showed that a total of 15 SiMPK genes were identified, and the encoded proteins contained 220-611 amino acids, the relative molecular weight ranged from 25.77 kD to 69.63 kD, and the isoelectric point ranged from 5.46 to 9.34. Phylogenetic analysis showed that SiMPK genes were divided into four groups. Group A, B, and C contained TEY motifs, and group D contained TDY motifs. SiMPK genes were distributed on chromosomes 1, 3, 4, 5, 8, and 9, and contained 3-11 exons. All SiMPK proteins contained motif 1 and motif 2. A number of cis-acting elements related to stress, hormones and plant growth and development were predicted in the promoter regions of the SiMPK genes. Most genes had obvious tissue expression specificity. Except for SiMPK21-2 and SiMPK6, the other members had obvious responses to 1 to 3 kinds of stresses, such as Uromyces setariae-italicae Yoshino infection, Ostrinia furnacalis feeding, and SA and MeJA treatments. The results laid a theoretical foundation for further research on the function of SiMPK genes in the biotic stresses of disease and pest in foxtail millet. Table and Figures | Reference | Related Articles | Metrics

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Physiological mechanism and regulation effect of low light on maize yield formation SUN Zhi-Chao, ZHANG Ji-Wang Acta Agronomica Sinica    2023, 49 (1): 12-23.   DOI: 10.3724/SP.J.1006.2023.13064 Abstract （512）   HTML （39）    PDF（pc） （4229KB）（630）       Knowledge map    Save As for global climate change, insufficient light during the growth periods has become one of the main factors restricting maize yield, increasing the risk of global food production and nutritional security. In this study, based on the previous experiments, we explored the physiological mechanism of low light on maize yield formation from the aspects of photosynthetic performance, nutrient absorption characteristics, grain formation, and filling characteristics. Under low light stress, the light harvesting ability of leaves was reduced, the stromal and grana thylakoids disintegrated, the activities of related enzymes were reduced, the photosystem was damaged, and the carbon assimilation ability was reduced, which further inhibited root development, significantly affected root morphology and function, and was not conducive to nutrient absorption and metabolism. Due to the insufficient nutrition supply, the development of tassel and ear was blocked, the morphological function of pollen and filaments was affected, resulting in low flower fertilization rate and decreased grain number per ear. Low light also reduced the number of endosperm cells— “sink” capacity, the structure and function of the endosperm transfer cells were affected, the endogenous hormonal balance was broken, sucrose, starch metabolism related enzyme activity decreased, internodes vascular bundle number and area reduced, transport and transformation ability were limited, eventualy led to the poor state of starch and the decreased grain weight significantly. Therefore, to alleviate the influence of low light stress on maize yield formation, it is urgent to establish indexes for systematic evaluation of shade tolerance varieties, accelerate the cultivation of new shade-tolerant varieties with high light efficiency by modern technology, and adopt cultivation measures such as increasing nitrogen fertilizer application, removing top leaves, spraying growth regulator and foliar fertilizer to improve maize yield. In the future, more attention should focus on root-shoot coordination and deeply explore the mechanism of low light stress, so as to provide the theoretical basis for the establishment of key techniques of maize resistance to yield increase. Table and Figures | Reference | Related Articles | Metrics

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Identification and evaluation of wheat germplasm resources at seedling stage SUN Xian-Jun, JIANG Qi-Yan, HU Zheng, LI Hong-Bo, PANG Bin-Shuang, ZHANG Feng-Ting, ZHANG Sheng-Quan, ZHANG Hui Acta Agronomica Sinica    2023, 49 (4): 1132-1139.   DOI: 10.3724/SP.J.1006.2023.21021 Abstract （396）   HTML （23）    PDF（pc） （441KB）（624）       Knowledge map    Save Soil salinization is one of the important abiotic stresses which affects wheat growth. The screening and breeding salt-tolerant wheat is of great significance to the utilization of salinized land. 19 hybrid wheat resources and 2 conventional varieties were used as the experimental materials, seeds were grown in vermiculite, 6 treatments of NaCl solutions with 0, 0.4%, 0.8%, 1.2%, 1.6%, and 2.0% from sowing were set, and 11 indicators related to the growth were analyzed and determined. The multivariate statistical analysis method was used to evaluate the salt-tolerant of wheat germplasm resources at seedling stage. The results showed that the saline tolerance coefficient of most indicators were the highest interquartile range under 1.2% salinity among germplasm resources, thus the 1.2% salinity was considered as the optimum concentration for identification saline tolerance. 11 indicators could be simplified into 3 principal components by using principal component analysis. Through the analysis of principal component contribution rate and membership function, the 3 principal component values were further reduced to D-value of comprehensive evaluation index. According to the D-value, 21 wheat germplasm resources were divided into 5 salt-tolerant levels (high tolerance, salt tolerance, medium tolerance, sensitive and high sensitivity) by cluster analysis. The comprehensive evaluation D-values of 13 hybrid wheat varieties were higher than that of Jiemai 19 and Jimai 22 at seedling stage. Combined with stepwise regression analysis, the optimal regression equation of salt-tolerant coefficient and D-value of 11 indicators was obtained: D= -0.743 + 0.779×PLL + 0.372×TNL + 1.273×PH + 0.336×PLC + 0.279×RL + 0.558×RDW. Based on the above regression equation, PLL (penultimate leaf length), PH (plant height), PLC (penultimate leaf chlorophyll), RL (root length), and RDW (root dry weight), could be used as evaluation indicators for wheat germplasm resources identification under 1.2% continuous salt stress at seedling stage. Table and Figures | Reference | Related Articles | Metrics

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Types and ratios of starch granules in grains and their roles in the formation and improvement of wheat quality properties GAO Xin, GUO Lei, SHAN Bao-Xue, XIAO Yan-Jun, LIU Xiu-Kun, LI Hao-Sheng, LIU Jian-Jun, ZHAO Zhen-Dong, CAO Xin-You Acta Agronomica Sinica    2023, 49 (6): 1447-1454.   DOI: 10.3724/SP.J.1006.2023.21065 Abstract （534）   HTML （74）    PDF（pc） （257KB）（622）       Knowledge map    Save Wheat flour is mainly composed of protein and starch. Gluten, especially the high-molecular-weight glutenin subunit, is the key factor determining the dough quality which has been widely accepted by breeders. However, the contribution of starch composition and physicochemical properties to dough quality has not been paid enough attention. Wheat starch has a bimodal size distribution and it is composed of A-type starch granules (diameter more than 10 μm) and B-type starch granules (diameter no more than 10 μm) according to the particle size. There are differences in the physicochemical properties of different types of starch granules. Therefore, the particle size distribution of starch affects the physicochemical properties of the total wheat starch, the gluten network structure, and the gluten-starch interaction of gluten, and finally affects the dough rheological properties, and processing characteristics. In summary, from a view of starch particle distribution, this article reviewed the development and regulation mechanism, physicochemical properties of A- and B-type starch granules, and their contribution to quality and yield. Strategies for future wheat breeding were proposed, that is, the starch properties should be selected and improved. The germplasm with high B-type starch granules proportion and strong gluten-starch interaction should be screened for further utilization. The objective of this study is to provide a reference for breeding the new high-quality and strong-gluten wheat varieties. Reference | Related Articles | Metrics

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A retrospective analysis of the historical evolution and developing trend of maize mega varieties in China from 1982 to 2020 BAI Yan, GAO Ting-Ting, LU Shi, ZHENG Shu-Bo, LU Ming Acta Agronomica Sinica    2023, 49 (8): 2064-2076.   DOI: 10.3724/SP.J.1006.2023.23067 Abstract （475）   HTML （39）    PDF（pc） （489KB）（621）       Knowledge map    Save Seed is the chip of agriculture and the upgrading of excellent varieties has played an important role in improving the yield of corn in China. It is of great practical significance to study the historical contribution and developing trend of mega maize varieties in China in recent 40 years. Based on the dataset of planting area of individual maize varieties released by the National Extension and Service Center of Agricultural Technology from 1982 to 2020, 27 mega maize varieties such as Zhengdan 958 in recent 40 years with the total promotion of 321 million hectares accounting for 29.09% of the total corn planting area in China were screened..There were four utmost mega varieties (Zhengdan 958, Zhongdan 2, Danyu 13, and Xianyu 335) and six massive mega varieties (Jundan 20, Yedan 2, Nongda 108, Yedan 13, Sidan 19, and Yandan 14). The promotion period was 8-30 years, with an average of 17.63 years, the maximum promotion area in a single year was 699,700-4,569,500 hm2, with an average of 1,507,900 hm2. It was mainly distributed in Shandong, Henan, Hebei, Jilin, Heilongjiang, Inner Mongolia, and other production regions and the provinces (regions) with 13 varieties exceeding 666,700 hm2 per year were Shandong, Henan, Hebei, Jilin, Heilongjiang, Inner Mongolia, Liaoning, and Sichuan. The proportion of planting area of mega varieties to the total area increased rapidly from 1982 to 1989, remained stable from 1990 to 1997, decreased after 1998, and decreased to about 12% by 2020. Some varieties such as Yufeng 303 and Zhongkeyu 505 had the potential to develop into mega varieties. In the future, intelligent design breeding will efficiently cultivate a new generation of breakthrough varieties and accelerate the improvement of maize yield. According to the current maize production problems and future development trends, it is recommended to further improve the regional test of maize varieties in terms of distribution layout, test accuracy and variety approval standards of regional tests. Table and Figures | Reference | Related Articles | Metrics

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Effects of planting density on solar and heat resource utilization and yield of maize varieties at different growth stages WU Xi, WANG Jia-Rui, HAO Miao-Yi, ZHANG Hong-Jun, ZHANG Ren-He Acta Agronomica Sinica    2023, 49 (4): 1065-1078.   DOI: 10.3724/SP.J.1006.2023.23032 Abstract （418）   HTML （30）    PDF（pc） （1113KB）（616）       Knowledge map    Save The objective of this study is to explore the response of maize solar and heat utilization, material production, and yield formation to density at different maturity stages, in order to provide a theoretical basis for high yield and efficiency cultivation of spring maize in Northern Shaanxi irrigation area. In 2019 and 2020, the field experiments were conducted by using two maize hybrids [Dongdan 60 (middle-late-maturing) and Dafeng 30 (middle-early-maturing)] with four planting density treatments [45,000 (D1), 60,000 (D2), 75,000 (D3), and 90,000 (D4) plants hm-2]. Leaf area index, canopy solar distribution, material production and transport, solar and heat utilization, yield and its composition were measured. The results showed that, compared with the low density, Dafeng 30 and Dongdan 60 reached the highest yield of 18,787.5 kg hm-2 and 16,953.0 kg hm-2 under the density of 90,000 plants hm-2 and 75,000 plants hm-2 and increased by 37.7 % and 41.4 %, respectively. The grain moisture content of Dafeng 30 was 11.5 % lower than that of Dongdan 60 under high yield. With the increase of planting density, the leaf area index of the population and the interception rate of solar energy in the upper canopy increased significantly, while the solar interception rate of the middle canopy decreased significantly, and Dongdan 60 decreased more than Dafeng 30. There was no significant difference in the interception rate of the lower canopy. For the utilization of solar radiation, the pre-silking intercepted photosynthetically active radiation and radiation use efficiency of Dafeng 30 were 7.9% and 1.7% higher than those of Dongdan 60, respectively. The post-silking intercepted photosynthetically active radiation and radiation use efficiency of Dafeng 30 were 9.5% and 14.9% lower than those of Dongdan 60, respectively. The correlation between radiation use efficiency and planting density revealed that the increase of planting density was more obvious in improving the light radiation utilization efficiency of Dafeng 30. Under D4 density, the growth period of Dafeng 30 was shortened by 4.3 days on average compared with that of Dongdan 60, and the average effective accumulated temperature of Dafeng 30 was 25.3°C less than that of Dongdan 60, but the temperature use efficiency was 25.3% higher than that of Dongdan 60, and the accumulated temperature required to reach the maximum dry matter accumulation rate was less than that of Dongdan 60. The pre-anthesis dry matter accumulation and post-anthesis dry matter transport rate of Dongdan 60 and Dafeng 30 were 26.7%, 34.6%, and 43.7%, 55.8% higher than those of D1, respectively. The post-silking dry matter accumulation and post-silking dry matter transport rate of Dafeng 30 were 14.5% and 12.3% higher than those of Dongdan 60, respectively. In comclusion, the population structure of Dafeng 30 was reconstructed under the dense planting can improve solar energy interception in the middle canopy, increase growth rate of dry matter and advance dry matter to reach the maximum growth rate, promote dry matter accumulation and transportat, improve solar and heat resource utilization efficiency, and achieve high yield and efficiency of spring maize in this area. Meanwhile, the lower moisture content of grain was suitable for mechanical harvesting. Table and Figures | Reference | Related Articles | Metrics

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Different responses of rice cultivars to salt stress and the underlying mechanisms YAN Jia-Qian, GU Yi-Biao, XUE Zhang-Yi, ZHOU Tian-Yang, GE Qian-Qian, ZHANG Hao, LIU Li-Jun, WANG Zhi-Qin, GU Jun-Fei, YANG Jian-Chang, ZHOU Zhen-Ling, XU Da-Yong Acta Agronomica Sinica    2022, 48 (6): 1463-1475.   DOI: 10.3724/SP.J.1006.2022.12027 Abstract （627）   HTML （39）    PDF（pc） （1151KB）（612）       Knowledge map    Save The objective of this study is to elucidate the responses of physiological traits and yield with different salt stress to salt-tolerant and salt-susceptible rice cultivars. Five salt-tolerant rice cultivars and two salt-susceptible rice cultivars were grown in pots with five different salt concentration levels including 0, 1, 2, 2.5, and 3 g kg-1 of per pot for two years. Results showed that the yields of salt-tolerant cultivars were less reduced than that of salt-susceptible cultivars, and salt-tolerant cultivars was able to tolerate higher salt concentration of 2.5 g kg-1. Salt-tolerant varieties produced higher grain yield mainly due to the greater total spikelets per area and higher filled grain percentage under salt stress. Salt-tolerant rice cultivars also had higher activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), higher contents of osmotic substances such as fructose, trehalose, and sorbitol, and higher K+/Na+ ratio from mid-tillering to heading. The crop growth rate from tillering to jointing and from heading to maturity, and photosynthetic rate at heading stage were higher in salt-tolerant cultivars than in salt-susceptible cultivars. The above results revealed that the differences in grain yields between salt-tolerant and salt-susceptible rice varieties were mainly due to the performances of physiological traits at mid-tillering, panicle initiation, and heading stages. These growth stages were the key stages that determined the number of panicles, spikelets per panicle, and the percentage of filled grains. The better physiological traits in the salt-tolerant rice varieties during key stages were the basis for higher grain yield. The results of this study could be helpful for the physiological researches and the breeding of salt-tolerant rice. Table and Figures | Reference | Related Articles | Metrics

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Enhancement of plant variety protection and regulation using molecular marker technology XU Yunbi, WANG Bing-Bing, ZAHNG Jian, ZHANG Jia-Nan, LI Jian-Sheng Acta Agronomica Sinica    2022, 48 (8): 1853-1870.   DOI: 10.3724/SP.J.1006.2022.23001 Abstract （686）   HTML （71）    PDF（pc） （834KB）（609）       Knowledge map    Save Plant variety protection is one of the important approaches for plant intellectual property protection. The distinctness, uniformity and stability (DUS) and essentially derived variety (EDV) are two major concepts in plant variety protection. DUS-EDV has been evaluated largely through morphological traits and pedigrees at the very beginning, to an integrated approach using morphological traits, pedigrees and molecular marker information and now to a stage largely driven by molecular diagnostics. Molecular diagnostic technology has been evolved from RFLP to SSR and SNP marker systems. The liquid SNP chip, represented by genotyping by target sequencing through capture in solution, has advantages of low cost, high flexibility in marker combinations and wide suitability for DUS-EDV evaluation across plant species. There are two important strategies in DUS-EDV evaluation, one being examined based on the analysis and comparison at the whole genome level and the other being examined at specific genomic regions for target functional loci associated with important phenotypes. Evaluation criteria should be established separately for DUS and EDV. The former can be evaluated based on the criteria constructed for specific fingerprint maps, haplotypes, unique alleles, genomic regions, target functional markers, minimum genetic homozygosity, and within-variety variation, whereas the latter can be examined by the genetic similarity between the potential EDV and check variety estimated using a large number of molecular markers evenly distributed across the genome, rather than by the number of markers. The number and the genomic coverage of molecular markers are two key factors affecting the efficiency and reliability in DUS and EDV assessment. Using only a small number of markers in such assessment will likely result in a large sampling error for the estimates. The threshold of genetic similarity required for distinguishing EDV and non-EDV can vary greatly across plant species and with the levels of plant variety protection. After reviewed the current status of plant variety protection across countries, the authors proposed that a national consultant expert committee should be established for consistent support to implement and improve DUS-EDV system, and an official database system should be constructed for public service and comparison of variety DNA fingerprint data to facilitate innovative activities in plant breeding. Table and Figures | Reference | Related Articles | Metrics

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Identification of rice blast resistance in xian and geng germplasms by genome- wide association study ZHOU Hai-Ping, ZHANG Fan, CHEN Kai, SHEN Cong-Cong, ZHU Shuang-Bing, QIU Xian-Jin, XU Jian-Long Acta Agronomica Sinica    2023, 49 (5): 1170-1183.   DOI: 10.3724/SP.J.1006.2023.22024 Abstract （513）   HTML （38）    PDF（pc） （1155KB）（606）       Knowledge map    Save Rice blast is one of the major fungal diseases that threaten rice production worldwide. To improve rice blast resistance, identifying blast resistant genes and introgressing them into elite rice varieties is an effective way. In this study, a panel of 212 xian accessions and 235 geng accessions collected worldwide were evaluated for resistance against five blast isolates at seedling stage. All of them showed large variations in resistance against five isolates, and 8 xian and 12 geng accessions were detected to present resistance to all five blast isolates. Using genome-wide association strategy, a total of 43 QTLs were identified for resistance to five isolates in mix population (xian subpopulation and geng subpopulation), including 9, 4, 14, 14, and 2 QTLs for GD00-193, GD08-T19, GD17-CQ16, HB1708, and HLJ13-856, respectively. Among them, 12 resistant QTLs were detected only in xian rice sub-population, 7 only detected in geng rice sub-population, and 1 simultaneously detected in both sub-populations, indicating that blast resistance was generally better in xian than in geng rice, and there was obvious differentiation in blast resistance between xian and geng rice. A total of 11 QTLs affected resistance to two or more trains or were simultaneously identified in two or more populations, and 23 candidate genes were identified by candidate interval association analysis and haplotype analysis. Different resistance candidate genes had different frequencies in xian and geng populations. The results provide germplasm resources and favorable genes information for molecular improvement of blast resistance in rice varieties and the breeding and utilization strategies of different resistance genes. Table and Figures | Reference | Related Articles | Metrics

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Effects of nitrogen fertilizer rates on grain yield and nitrogen use efficiency of japonica-indica hybrid rice cultivar Yongyou 1540 and its physiological bases XU Ran, CHEN Song, XU Chun-Mei, LIU Yuan-Hui, ZHANG Xiu-Fu, WANG Dan-Ying, CHU Guang Acta Agronomica Sinica    2023, 49 (6): 1630-1642.   DOI: 10.3724/SP.J.1006.2023.22040 Abstract （305）   HTML （36）    PDF（pc） （1154KB）（582）       Knowledge map    Save The objective of this study is to understand how nitrogen (N) application rates affected on grain yield and N use efficiency (NUE) of japonica-indica hybrid rice cultivar Yongyou-1540 and its physiological bases. In the present study, a japonica-indica hybrid rice cultivar Yongyou 1540, which was widely planted in Zhejiang province was field grown in 2020 and 2021, and four N application rates [0 kg hm-2 (N0), 80 kg hm-2 (N1), 160 kg hm-2 (N2), and 240 kg hm-2 (N3)] were applied during rice growing season. The results indicated that, (1) N application rate had significant effects on grain yield and NUE of rice. Grain yield was significantly increased with the increase of N application rate from 0 kg hm-2 to 160 kg hm-2, and the increase in grain yield was mainly attributed to the increase in total spikelets per unit area. However, there were no significantly difference in grain yield between N2 and N3 treatments, which was mainly due to the reduce in grain filling percentage in N3 treatment. When compared with N2 treatment, N3 treatment significantly reduced N harvest index and NUE, including agronomic N use efficiency (AEN), N recovery efficiency (REN), N partial factor productivity (PFPN), and internal N use efficiency (IEN). (2) N application rate had significant effects on shoot growth and development. Shoot dry weight was significantly increased at jointing, heading, and maturity stages and harvest index was significantly decreased with the increase of N application rate from 0 kg hm-2 to 240 kg hm-2. The net photosynthetic rate of flag leaf, the concentration of zeatin plus zeatin riboside (Z+ZR) in flag leaves, and the activities of key enzymes involved in sucrose-to-starch conversion in grains were significantly increased with the increase of N application rate from 0 kg hm-2 to 160 kg hm-2, however, N3 treatment could not increase or even reduce the above indicators compared with N2 treatment. (3) N application rate had significant effects on rice root morphological and physiological traits. Root dry weight, root dry weight in both 0-10 cm and 10-20 cm soil layers, total root length, root length density, specific root length at jointing, heading, and maturity stages, and root oxidation activity (ROA) and concentration of Z+ZR in both roots and root-bleeding sap at mid- and late grain filling stages were significantly increased with the increase of N application rate from 0 kg hm-2 to 160 kg hm-2. However, when compared with N2 treatment, N3 treatment significantly increased root dry weight, and root dry weight in 0-10 cm soil layer, total root length and root length density. (4) The results of the correlation analysis showed that ROA, and concentration of Z+ZR in roots or in root-bleeding sap, were significantly positively correlated with net photosynthetic rate of flag leaves, the concentration of Z+ZR in flag leaves, and activities of key enzymes involved in sucrose-to-starch conversion in grains. Generally, the appropriate N application rate could improve rice root morphological and physiological traits and promote shoot growth and development, and then improved plant physiological performances during the mid- and late grain filling stages, and finally achieved the due goal of increase both grain yield and NUE. Table and Figures | Reference | Related Articles | Metrics

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Effect of agricultural meteorological disasters on the production corn in the Northeast China LI Yi-Jun, LYU Hou-Quan Acta Agronomica Sinica    2022, 48 (6): 1537-1545.   DOI: 10.3724/SP.J.1006.2022.03061 Abstract （495）   HTML （18）    PDF（pc） （949KB）（582）       Knowledge map    Save Agricultural meteorological disasters are the main natural disasters that threaten grain output. In recent years, with climate change, agricultural meteorological disasters are more and more frequent, and their impact on northeast China is also increasing. In this paper, to make better use of advantages and avoid disadvantages in actual production to ensure food production safety, spring corn in three provinces of northeast China was taken as the research object to discuss the impact of major agricultural meteorological disasters in this region on spring corn yield and its degree. The results showed that agricultural meteorological disasters could explain about 50% of the fluctuation of spring corn yield in Northeast China, and the main agricultural meteorological disasters that affected spring corn production had changed from cold damage in the traditional sense to drought. Under the background of climate warming, the main factor affecting spring corn production was changed from thermal condition to water condition, and drought had become the primary disaster threatening spring corn production. The agricultural meteorological disasters that affected the spring corn yield in Liaoning province were drought, flood, and wind in order of the degree of influence. The agricultural meteorological disaster that affected spring corn yield in Jilin province was only drought. The agricultural meteorological disasters affecting the yield of spring corn in Heilongjiang province were ranked as flood, drought, and cold damage according to the degree of impact. In conclusion, due to geographical differences, the main agro-meteorological disasters affecting the corn production in the three provinces of Northeast China were also different, and their complexity was not the same, which cannot be generalized in the specific study. Table and Figures | Reference | Related Articles | Metrics

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Molecular mapping and validation of quantitative trait loci for spike-related traits and plant height in wheat HU Wen-Jing, LI Dong-Sheng, YI Xin, ZHANG Chun-Mei, ZHANG Yong Acta Agronomica Sinica    2022, 48 (6): 1346-1356.   DOI: 10.3724/SP.J.1006.2022.11055 Abstract （595）   HTML （38）    PDF（pc） （786KB）（573）       Knowledge map    Save Spike-related traits and plant height are important target traits in wheat breeding. In the present study, a population of 198 recombinant inbred lines (RILs) derived from the cross between a CIMMYT wheat line C615 and Yangmai 13 (YM13) was constructed, followed by genotyping with Wheat 90K SNP array and phenotyping of spike-related traits and plant height in three environments to excavate QTLs (quantitative trait loci) for these traits. Using composite interval mapping method, we identified one QTL for total spikelet number per spike (TSS), two QTLs for spike length (SL), two QTLs for spikelet compactness (SC), and three QTLs for plant height (PH). QSN.yaas-3B and QPH.yaas-3B overlapped on the chromosome 3B. QSL.yaas-5A, QSC.yaas-5A and QPH.yaas-5A overlapped on the chromosome 5A. QSL.yaas-6A and QSC.yaas-6A overlapped on the chromosome 6A. QSN.yaas-3B/QPH.yaas-3B and QSL.yaas-6A/QSC.yaas-6A had not been reported yet, and were likely to be novel loci. The SNP marker closely linked to QSL.yaas-5A/QSC.yaas-5A/QPH.yaas-5A was then converted into one Kompetitive Allele Specific PCR (KASP) marker (QC615-5A-KASP), and validated in a panel of 105 wheat lines. The results would be useful for improvement of yield related traits in wheat breeding. Table and Figures | Reference | Related Articles | Metrics

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ALGWAS: two-stage Adaptive Lasso-based genome-wide association study YANG Wen-Yu, WU Cheng-Xiu, XIAO Ying-Jie, YAN Jian-Bing Acta Agronomica Sinica    2023, 49 (9): 2321-2330.   DOI: 10.3724/SP.J.1006.2023.23072 Abstract （319）   HTML （35）    PDF（pc） （874KB）（573）       Knowledge map    Save As mainstream methods for genome-wide association analysis, mixed linear model methods have been widely used. However, the existing methods still have the problem of low detection power. In this study, a two-stage Adaptive Lasso-based genome-wide association analysis (ALGWAS) method was proposed. In the first stage, single nucleotide polymorphism (SNP) associated with target traits were screened by Adaptive Lasso, a variable selection method. In the second stage, SNPs selected from the first stage were put into the linear model as the covariates for genome-wide scanning. Compared with fastGWA, GEMMA and EMMAX, the ALGWAS method had the highest detection power and lower false discovery rate (FDR) in the simulation experiments. The above four methods were applied to genome-wide association analysis of Complete-diallel plus Unbalanced Breeding-like Inter-Cross (CUBIC) population of 1341 individuals in maize. ALGWAS method can detect the genes (ZmMADS69, ZmMADS15/31, ZmZCN8, and ZmRAP2.7) related to days to tasseling, the genes (ZmBRD1 and ZmBR2) related to plant height, and the genes (ZmUB2, ZmKRN2, and ZmCLE7) related to yield, while the other three commonly used genome-wide association analysis methods had low detection efficiency. In this study, a non-mixed linear model class of genome-wide association analysis method was proposed, which had higher detection advantage for microeffect polygenes and provided a new way for genetic analysis of complex traits. Table and Figures | Reference | Related Articles | Metrics

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Effects of light intensity and nitrogen fertilizer interaction on carbon and nitrogen metabolism at grain-filling stage and its relationship with yield and quality of southern soft japonica rice CHEN Xin-Yi, ZHU Ying, MA Zhong-Tao, ZHANG Ming-Yue, WEI Hai-Yan, ZHANG Hong-Cheng, LIU Guo-Dong, HU Qun, LI Guang-Yan, XU Fang-Fu Acta Agronomica Sinica    2023, 49 (11): 3042-3062.   DOI: 10.3724/SP.J.1006.2023.22054 Abstract （262）   HTML （33）    PDF（pc） （1970KB）（572）       Knowledge map    Save Southern soft japonica rice Nanjing 9108 and Yangnongxiang 28 were selected as the experimental materials, and two light intensity treatments, and four nitrogen treatments were set. Light intensity treatments [100% natural light intensity (L1) and 50% natural light intensity (L2)] and four nitrogen treatments [no nitrogen fertilizer (N1) in the middle and late growth stages, one-time nitrogen fertilizer applied at the top sixth leaf stage (N2), one-time nitrogen fertilizer applied at the top fourth leaf stage (N3), and one-time nitrogen fertilizer applied at the top second leaf stage (N4)] were conducted at grain-filling stage. The difference of carbon and nitrogen metabolism at grain-filling stage and its effects on rice yield and quality under the conditions of different light intensity and nitrogen application period as well as light-nitrogen interaction conditions were investigated. The results showed that with the decrease of light intensity at grain-filling stage the net photosynthetic rate of flag leaf decreased by 7.35%-42.36% on average, sucrose phosphate synthase (SPS), and sucrose synthase (SS) had low activity, the C/N ratio of leaves decreased by 3.98-6.49, the transportation of photosynthetic products to grains decreased, and the content of grain starch (including amylose) decreased. Meanwhile, the activities of nitrate reductase (NR), glutamine synthetase (GS), and glutamate synthetase (GOGAT) increased, plant nitrogen concentration increased, and the accumulation of protein increased relatively, which were not conducive to the formation of yield and good quality. After the application of nitrogen fertilizer at the middle and late growth stages, the activities of key enzyme in carbon and nitrogen metabolism in leaves were significantly increased, the aging of leaves was slowed down, and the grain-filling period of rice was prolonged, which were conducive to the increase of yield. With the delay of nitrogen fertilizer application period, nitrogen metabolism became more vigorous, and the protein content in grain had a relative significant increase, resulting in the decrease of the ratio of starch to protein and the ratio of amylose to protein, and the decrease of taste value. Under the experimental condition, normal light intensity combined with nitrogen fertilizer treatment (L1-N3) at the top fourth leaf stage synergistically improved the activities of key enzymes of carbon and nitrogen metabolism in leaves, thus the photosynthetic products and nitrogen-containing compounds were transported to grains in the appropriate proportions. Ultimately, the ratio of starch to protein in grain ranged from 11.43 to 12.03, and the ratio of amylose to protein ranged from 1.34 to 1.50, the rice had low hardness, high viscosity, and balance as well as good taste, high yield, and excellent quality could be obtained simultaneously. Table and Figures | Reference | Related Articles | Metrics

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Effects of staged potassium application on grain yield and nitrogen use efficiency of winter wheat under reduced nitrogen conditions ZHANG Xiang-Yu, HU Xin-Hui, GU Shu-Bo, Lin Xiang, YIN Fu-Wei, WANG Dong Acta Agronomica Sinica    2023, 49 (2): 447-458.   DOI: 10.3724/SP.J.1006.2023.21013 Abstract （351）   HTML （30）    PDF（pc） （804KB）（569）       Knowledge map    Save In order to explore the effect of potassium fertilizer application on the yield and nitrogen use efficiency of winter wheat in different stages, and to determine the high-yield and efficient potassium fertilizer operation plan for winter wheat under the condition of nitrogen reduction, the high-yield and strong-gluten winter wheat variety Gaoyou 5766 was selected as the test materials in this experiment. During the growing season, a two-factor randomized block design was used to set three nitrogen application levels [conventional nitrogen application rate (240 kg hm-2, N1), nitrogen application rate reduced by 20% (192 kg hm-2, N2), and nitrogen application rate reduced by 40% (144 kg hm-2, N3)] and two potassium fertilizer application schemes [all potassium fertilizers applied at the sowing stage (K1) and potassium fertilizer applied in stages (50% was applied at the sowing stage and 50% was applied at the jointing stage, K2)]. The results showed that under the same potassium fertilizer application scheme, the grain yield of N2 treatment was not significantly different from that of N1 treatment, and the grain yield of N3 treatment was significantly lower than that of N1 treatment, with a decrease of 9.0%-11.6%. Under the same nitrogen application rate, potassium application by stages could significantly improve grain yield and nitrogen use efficiency of winter wheat. Compared with K1 treatment, K2 treatment significantly inhibited the leaching of nitrate nitrogen into deep soil layers, increased nitrogen accumulation in winter wheat plants, and increased flag leaf photosynthetic rate and nitrate reductase activity, grain filling rate, the number of grains per spike, and 1000-grain weight. Grain yield and nitrogen use efficiency increased by 21.7% and 20.2% under the conventional nitrogen application rate, by 26.9% and 26.2% under the N2 level, and by 25.2% and 21.1% under the N3 level, respectively. The grain yield, nitrogen uptake efficiency, nitrogen use efficiency, and nitrogen partial productivity of N3K2 treatment were significantly higher than those of N1K1 treatment. The above results showed that potassium application in stages could greatly improve the grain yield and nitrogen use efficiency of winter wheat under different nitrogen application rates. Using the nitrogen application rate of 192 kg hm-2 combined with potassium application in stages, the grain yield and nitrogen uptake efficiency of winter wheat were the highest, and the nitrogen use efficiency and nitrogen partial productivity also reached a high level. It is a high-yield and efficient nitrogen-potassium fertilizer application scheme. Table and Figures | Reference | Related Articles | Metrics

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Differences of physiological responses and transcriptional regulation of alfalfa with different drought tolerances under drought stresses CHEN Li, WANG Jing, QIU Xiao, SUN Hai-Lian, ZHANG Wen-Hao, WANG Tian-Zuo Acta Agronomica Sinica    2023, 49 (8): 2122-2132.   DOI: 10.3724/SP.J.1006.2023.24205 Abstract （334）   HTML （36）    PDF（pc） （1732KB）（558）       Knowledge map    Save Alfalfa is the most important legume forage, which is often planted in aird or semi-arid regions. The objective of this study is to explore the responsive mechanism of alfalfa with different drought tolerance to drought stress, which provides the theoretical basis for tolerant breeding of alfalfa. In this study, the new variety Medicago sativa ‘Zhongke 1’ was used as the test material, and M. sativa ‘Sanditi’ was used as the control. The effects of drought stress on growth traits, photosynthesis, chlorophyll concentration, leaf water content, osmotic adjustment substances, and antioxidant enzyme activities were determined by natural drought strategy in pots. The deferentially expressed genes were compared by transcriptome analysis. Drought stress significantly reduced plant height, biomass, relative water content of leaves, photosynthetic rate, transpiration rate, stomatal conductance, intercellular carbon dioxide and chlorophyll concentration of alfalfa. Compared with Sanditi, Zhongke 1 revealed the lower malondialdehyde concentration and electrical conductivity under drought stress, but stronger osmotic regulation ability and superoxide radical scavenging ability. Transcriptome sequencing identified 5308 and 8053 drought-responsive genes of Zhongke 1 and Sanditi, respectively. GO functional annotation demonstrated that 346 drought-responsive genes were significantly enriched in six GO item categories in Zhongke 1, while 1683 drought-responsive genes in Sanditi were significantly enriched in 29 GO item categories. The relative expression levels of 19 key drought-tolerant genes in Zhongke 1 were significantly higher than those in Sanditi. Alfalfa may maintain a relatively high photosynthetic rate by up-regulating the relative expression levels of drought tolerant genes SUS, P5CS, LEA, SOD, POD, PEPC, and NCED, thus improving osmotic regulation ability and antioxidant enzyme activity. The results provide a theoretical basis for further exploration of alfalfa’s candidate genes in response to drought stress and drought tolerant breeding. Table and Figures | Reference | Related Articles | Metrics

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Haplotype analysis of soybean leaf type regulator gene Ln and its homologous genes LI Gang, ZHOU Yan-Chen, XIONG Ya-Jun, CHEN Yi-Jie, GUO Qing-Yuan, GAO Jie, SONG Jian, WANG Jun, LI Ying-Hui, QIU Li-Juan Acta Agronomica Sinica    2023, 49 (8): 2051-2063.   DOI: 10.3724/SP.J.1006.2023.24208 Abstract （301）   HTML （31）    PDF（pc） （1158KB）（540）       Knowledge map    Save Soybean leaf type is an important component of ideal plant type, which is of great significance for the breeding of soybean varieties. In this study, we analyzed the haplotype of Ln and its homologous gene (Glyma.10G273800) in 598 materials from different regions of China. Ln gene and homologous gene contained three haplotypes (Hap1-Hap3), respectively. There was no significant difference in leaf length between the three haplotypes of Ln gene, and Hap2 was significantly different from Hap1/Hap3 in leaf width, leaf area, and leaf length width ratio. There were significant differences between Hap3 and Hap2 of Ln homologous gene in different leaf types. There was no difference in the ratio of leaf length to width between Hap1 and Hap2. There was no significant difference in leaf width phenotype at the 4th leaf site, and Hap1 at the 5th leaf site was significantly lower than Hap2. Leaf length, leaf area, and leaf circumference Hap1 were significantly lower than Hap2. In terms of geographical distribution, Hap2 of Ln gene was mainly distributed in high latitude and high altitude regions, and no obvious regional bias was detected in the distribution of the three haplotypes of its homologous genes. Genetic analysis showed that only D9H of Hap2 in Ln gene had artificial selection signal, while the other two mutation sites in Ln gene and two mutation sites in homologous gene had no artificial selection signal. This study provides the theoretical basis for soybean leaf type breeding and has positive significance for increasing soybean yield. Table and Figures | Reference | Related Articles | Metrics

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Genome editing of BnaMPK6 gene by CRISPR/Cas9 for loss of salt tolerance in Brassica napus L . ZHANG Wen-Xuan, LIANG Xiao-Mei, DAI Cheng, WEN Jing, YI Bin, TU Jin-Xing, SHEN Jin-Xiong, FU Ting-Dong, MA Chao-Zhi Acta Agronomica Sinica    2023, 49 (2): 321-331.   DOI: 10.3724/SP.J.1006.2023.24013 Abstract （397）   HTML （42）    PDF（pc） （5159KB）（538）       Knowledge map    Save Brassica napus L. is an important oil crop. MPK6 (Mitogen-Activated Protein Kinases 6) is activated by various stresses to control plant stress tolerance, which is the key gene in response to abiotic stresses. However, the function of MAPK6 in B. napus stress tolerance is still unclear. Gene structure and protein sequence analysis showed that MPK6gene structures were similar, and all proteins had the same STKc_TEY_MAPK domain in Brassica. To explore the potential role of BnaMPK6, the BnaMPK6 mutants were generated by CRISPR/Cas9 genome editing technology. Two quadruple mutants, cr-bnampk6-13-1 and cr-bnampk6-49-1, were obtained. cr-bnampk6 mutant lines were hypersensitive to salt treatment (100 mmol L-1 and 150 mmol L-1), the growth of the mutant was strongly inhibited after salt treatment, and the plant height and fresh weight were significantly lower than those of wild-type plants, but there was no significant difference in root length. In addition, reactive oxygen species (ROS), malondialdehyde (MDA), and free proline were more accumulated in cr-bnampk6 mutant lines. In conclusion, these results revealed that BnaMPK6 gene positively regulated salt tolerance in B. napus, providing theoretical and technical supports for genetic improvement of salt tolerance in Brassica napus. Table and Figures | Reference | Related Articles | Metrics

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Yield and yield components of maize response to high plant density under reduced water and nitrogen supply WEI Jin-Gui, GUO Yao, CHAI Qiang, YIN Wen, FAN Zhi-Long, HU Fa-Long Acta Agronomica Sinica    2023, 49 (7): 1919-1929.   DOI: 10.3724/SP.J.1006.2023.23056 Abstract （278）   HTML （17）    PDF（pc） （539KB）（537）       Knowledge map    Save Water shortage and high fertilizer input have become the dominant factors restraining maize production in arid oasis irrigation area, it is urgent to study the technology of stable yield and increasing yield of crops with reduced water and fertilizer. To provide basis for establishing the efficient technology of stable and high yield of maize with water and nitrogen reduction, the effects of increasing density on dry matter accumulation, grain yield and yield components of maize were investigated under reduced water and nitrogen supply. A split-split plot field experiment was conducted in 2020 and 2021. Under two irrigation levels on local conventional irrigation reduced by 20% (W1) and local conventional irrigation (W2), and two levels of nitrogen fertilizer at a local conventional nitrogen reduced by 25% (N1) and local conventional nitrogen (N2), the response characteristics of dry matter accumulation and yield of maize were studied when maize density increased from 75,000 plants·hm-2 (low density, D1) by 30% (medium density D2), and by 60% (high density D3). The results showed that the grain yield of maize was significantly decreased with the reduced water and nitrogen supply, and increasing planting density by 30% could compensate the negative effect on the decrease of yield. Under the reduced water supply while maintaining N application rate, the dense planting density could significantly increase grain yield. In the two experimental years, the yield of W1 was 3.0% lower than W2. The grain yield of N1 was 12.9% lower than N2. Compared with D1, D2, and D3 increased grain yield by 12.9% and 9.2%, respectively. Compared with W2N2D1, the grain yield of W1N1D1 was decreased by 12.3%, but there was no significant difference between W2N2D1 andW1N1D2 treatments. Under the reduced water and nitrogen supply, increasing density could compensate the negative effect on the decrease of yield was mainly attributed to promoting the dry matter accumulation from early-filling to maturing stage and improving panicle number significantly. Compared with W2N2D1, the dry matter accumulation of W1N1D2 was increased by 5.8% from the early-filling to maturing stage of maize, but there were no significant differences on Vmax (maximum rate of dry matter accumulation), Vmean (mean increase rate of dry matter accumulation), Tm (the days of the maximum rate), and HI (harvest index) between W1N1D2 and W2N2D1 treatments. Compared with W2N2D1, the spike number of W1N1D2 was increased by 24.7%, but the number of kernels per spike and 1000-kernel weight of W1N1D2 were decreased by 19.3% and 14.8%, respectively. The grain yield of W1N2D2 was 13.9% higher than W2N2D1. When the nitrogen application rate was unchanged, the main reasons for the reduced irrigation, increasing density, and stable yield were the increase of dry matter accumulation, Vmean, HI, and the panicle number. Compared with W2N2D1, W1N2D2 increased panicle number, dry matter accumulation, Vmean and HI by 24.8%, 10.2%, 8.4%, and 4.7%, respectively, but there was not significant difference in 1000-kernel weight between W1N2D2 and W2N2D1 treatments. In conclusion, increasing planting density by 30% under the simultaneous reduction of water and nitrogen in the experiment was a feasible measure to save water and nitrogen for stable and high yield of maize in oasis irrigation areas. Increasing planting density by 30% was a feasible measure to save water and increase yield of maize when irrigation water was reduced by 20% while maintaining N application rate Table and Figures | Reference | Related Articles | Metrics