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    12 February 2022, Volume 48 Issue 2
    • REVIEWS
      Phylogeny of wild Setaria species and their utilization in foxtail millet breeding
      ZHAO Mei-Cheng, DIAO Xian-Min
      Acta Agronomica Sinica. 2022, 48(2):  267-279.  doi:10.3724/SP.J.1006.2022.14047
      Abstract ( 814 )   HTML ( 57 )   PDF (526KB) ( 802 )   Save
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      Foxtail millet (Setaria italica) was domesticated from the wild ancestor, green foxtail (S. viridis), about ten thousand years ago in China. Foxtail millet belongs to Setaria genus, which includes about 125 species of panicoid grasses worldwide, and 15 species of them in China varied from diploid to octoploid. Currently, six genomes in the Setaria genus have been identified by GISH (genomic in situ hybridization). Molecular phylogenetic analyses show that the Setaria genus is polyphyletic, in line with the characteristic of diversified genomes. Phylogeny of Setaria genus reveal that foxtail millet is most closely related with green foxtail, and then S. fabrei and S. verticillata, and that A genome of S. italica/S. viridis appears to be closer to B genome of S. adhaeran and C genome of S. grisebachii than the other known genomes. For utilization of wild species resources, foxtail millet breeders have successfully introduced the naturally mutated herbicide-resistant genes from green foxtail into cultivars, resulting in the herbicide-resistant foxtail millet variety. Here, we review the recent advances of wild species of foxtail millet in species classification, genome constitution and phylogenetic relationships, and highlight the utility of the wild species resources for breeding and domestication of foxtail millet. We also discuss the potentials of the wild Setaria species in discovery of domestication genes and breeding in foxtail millet in the future.

      Advances of QTL mapping for seed size related traits in peanut
      HUANG Li, CHEN Yu-Ning, LUO Huai-Yong, ZHOU Xiao-Jing, LIU Nian, CHEN Wei-Gang, LEI Yong, LIAO Bo-Shou, JIANG Hui-Fang
      Acta Agronomica Sinica. 2022, 48(2):  280-291.  doi:10.3724/SP.J.1006.2022.14046
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      Peanut is an important oil and economic crop in China. Currently, the domestic production of peanut remains far below the needs of consumers. Thus, further improving the yield per unit area is a crucial approach to meet the rising market demand. Seed size related traits are important agronomic traits in peanut, fundamentally contributing to improving yield per unit area. This review summarized the research progress on the regulatory pathways of seed size in plants, molecular markers, genetic linkage map construction, and QTL mapping of seed size related traits in peanut. We discussed the frontline challenges and opportunities for the coming researches of peanut seed related traits and the perspectives of yield improvement in peanut.

      CROP GENETICS & BREEDING·GERMPLASM RESOURCES·MOLECULAR GENETICS
      Phenotypic and genetic analyses of a rice mutant eed1 with defected embryo and endosperm development
      YANG Jin, BAI Ai-Ning, BAI Xue, CHEN Juan, GUO Lin, LIU Chun-Ming
      Acta Agronomica Sinica. 2022, 48(2):  292-303.  doi:10.3724/SP.J.1006.2022.12013
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      A stably inherited embryo and endosperm defective mutant, named embryo and endosperm defective 1 (eed1), was obtained from the mutant population of rice Zhonghua 11, generated by ethylmethane sulfonate (EMS). The 1000-grain weight, grain length, grain width, grain thickness, germination rate, total starch, amylose, and storage protein contents in eed1 mature caryopses were significantly decreased compared with wild type. In eed1, the caryopses were shrunken and the endosperm was opaque. Scanning electron microscopy observation revealed that starch granules in eed1 endosperm cells were loosely packed, in single, disperse and spherical forms. The embryo of eed1 was abnormal, and some caryopses showed no sign of embryonic differentiation. Most genes involved in biosynthesis of starch and storage protein were down-regulated in eed1 endosperm by qRT-PCR. EED1 was mapped in an interval of 672 kb on chromosome 9 using a F2 population derived from a cross between eed1 and Nanjing 6. The region contained 114 open reading frames. This study lays a foundation for further studying EED1 gene in regulating development of rice embryo and endosperm.

      Dissecting the genetic architecture of maize kernel size based on genome-wide association study
      QU Jian-Zhou, FENG Wen-Hao, ZHANG Xing-Hua, XU Shu-Tu, XUE Ji-Quan
      Acta Agronomica Sinica. 2022, 48(2):  304-319.  doi:10.3724/SP.J.1006.2022.13002
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      Kernel size related traits are one of the important compounds of yield, and they are also complex quantitative traits regulated by multiple genes. Mining the key regulatory genes of maize kernel size related traits will help to improve the yield. In this study, 212 excellent maize inbred lines were selected as materials. The kernel length, kernel width, and kernel thickness were measured in 2018 and 2019, respectively, and we performed genome-wide association study (GWAS) based on 73,006 single nucleotide polymorphic (SNP) markers uniformly distributed in maize genome. Based on the FarmCPU algorithm, 47 SNP markers associated with kernel size related traits were detected on 10 chromosomes in maize. Combined with the public dynamic spatio-temporal transcriptional data of kernel development of B73 maize inbred line, 58 candidate genes related to kernel size were detected in the linkage disequilibrium (LD) region marked by significant SNP. The proteins encoded by candidate genes interacted with multiple proteins and participated in and regulated many biological processes closely related to kernel development. These results provide a new reference for understanding the molecular regulation mechanism of maize kernel development, improving kernel size and increasing crop yield.

      Advantages of small grain male sterile lines in seed production for a new combination Zhuoliangyou 141 through the mixed-sowing manner
      ZHOU Jie-Qiang, ZHANG Gui-Lian, DENG Hua-Bing, MING Xing-Quan, LEI Bin, LI Fan, TANG Wen-Bang
      Acta Agronomica Sinica. 2022, 48(2):  320-331.  doi:10.3724/SP.J.1006.2022.02045
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      Traditional hybrid breeding is backward, low benefit, and high cost, which restricts the promotion and application in hybrid rice. However, Small Grain TMS lines are easy to be mechanically separated after mixed-sowing and mixed-harvesting. Their application will promote the realization of complete Mechanization of Hybrid Rice Seed Production, leading to the reduction of cost and the improvement of seed production efficiency. In this study, we investigated the agronomic characteristics and outcrossing rates suitable for Mechanization of Hybrid Rice Seed Production, using the Small Grain male sterile line Zhuo 201S, Large Grain restorer line R141, and their combination Zhuoliangyou 141 as materials for mixed-sowing and large-scale seed production practice. The results demonstrated that compared with the control TMS C815S, Zhuo 201S plants were shorter, exhibiting longer and more erect ear, fewer glume opening, lower percentage of panicle enclosure and germination on ears. Moreover, Zhuo 201S plants were resistant to smut disease but sensitive to “920” treatment and had weak seed-shattering characteristic. However, R141 plants were tall and insensitive to environmental temperature with large amount of pollen and a long florescence. Both Zhuo 201S and R141 had good outcrossing characteristics. The grain thickness of Zhuo 201S and R141 was 1.71 mm and 2.23 mm, respectively. The 1000-grain weight of Zhuo 201S and R141 was 14.00 g and 28.20 g, respectively. Due to the significant difference in grain sizes, the hybrid F1 seeds could be easily separated with the male parent seeds through a special sieve with narrow and long apertures. The percentage of male parent seeds mixed in hybrid seeds was 0 while the hybrid seed loss rate was 2.31%, suggesting that the seed purity met the standards for Mechanization of Hybrid Rice Seed Production. Compared with the traditional seed production mode, the basic seedling of male parent was reduced by 85%, the capacity of female parent was increased by 20%, the seed production yield was increased by 21.37%, and the comprehensive benefit of seed production was increased by 31.4%. Zhuoliangyou 141 was endowed with the advantages suitable for mechanized production by mix-sowing, with excellently agronomic traits and outcrossing properties along with huge difference in grain size from its parents. Therefore, the whole process of Zhuoliangyou 141 mechanized seed production had a broad application prospect.

      Sugarcane ubiquitin-like protein UBL5 responses to SCMV infection and interacts with SCMV-6K2
      YANG Zong-Tao, LIU Shu-Xian, CHENG Guang-Yuan, ZHANG Hai, ZHOU Ying-Shuan, SHANG He-Yang, HUANG Guo-Qiang, XU Jing-Sheng
      Acta Agronomica Sinica. 2022, 48(2):  332-341.  doi:10.3724/SP.J.1006.2022.14001
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      Ubiquitylation plays key roles in the regulation of protein function, growth and development, and response to stress. Ubiquitin-like proteins (UBLs) are the main components of the ubiquitin-proteasome system (UPS). In our previous study, the UBL5 homologue was isolated from sugarcane (Saccharum spp. hybrid) by yeast two-hybrid (Y2H) with the 6K2 of Sugarcane mosaic virus (SCMV) as bait, and then designated as ScUBL5 with 73 aa in length. In the present study, the interaction of ScUBL5 with the SCMV-6K2 was further confirmed by bimolecular fluorescence complementation assays (BiFC). Bioinformatics analysis showed that ScUBL5 is a stable hydrophilic non-secretory protein without signal peptide or transmembrane domain. Phylogenetic tree analysis showed that ScUBL5 is species specific. Subcellular localization analysis showed that ScUBL5 is localized in cytoplasm and nucleus. ScUBL5 gene shows obvious tissue specificity in sugarcane by real-time quantitative PCR analysis. The expression levels of ScUBL5 gene in the established morphogenesis tissues such as the 1st leaf, the 7th leaf, the 8th internode and the root were significantly higher than those in the immature tissues such as leaf roll and the 3rd internode. The expression of ScUBL5 gene is significantly affected by SCMV infection. ScUBL5 was significantly upregulated in the early stage of SCMV infection, then downregulated but significantly higher than the control at the late stage of SCMV infection.

      Xian-geng identification by SNP markers in Oryza sativa L.
      ZHENG Xiang-Hua, YE Jun-Hua, CHENG Chao-Ping, WEI Xing-Hua, YE Xin-Fu, YANG Yao-Long
      Acta Agronomica Sinica. 2022, 48(2):  342-352.  doi:10.3724/SP.J.1006.2022.02085
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      Asian cultivated rice (Oryza sativa L.) is divided into two subspecies of xian and geng. With the development of hybrid rice and utilization of interspecific heterosis, the boundaries between xian and geng are becoming more and more vague. In this study, based on the SNP-index value of 20 million single nucleotide polymorphism (SNP) loci from 3000 rice germplasm resources, we captured 4084 xian-geng specific SNP loci named as 4k-SNP and used the xian-geng index as an indicator for xian-geng identification. Furthermore, the 4k-SNP was reduced to 40-SNP (40 SNP loci) for indica/japonica identification by using the statistical analysis methods such as large-scale simple random sampling based on the dimensionality reduction algorithms. To verify the effectiveness of 40-SNP on xian-geng identification, 82 bred varieties were used in this study to compare the results of 40-SNP xian-geng identification and 4k-SNP identification. The result showed that the geng index obtained from 40-SNP and 4k-SNP were very close, and the correlation coefficient was 0.99. Moreover, a total of 49 varieties, belonging to six subgroups (indica, aus, rayada, aromatic, tropical japonica, and temperate japonica), were used to compare the xian-geng identification results of 40-SNP with those of 4k-SNP and Cheng’s index. And the correlation coefficients of xian-geng identifications between 40-SNP and 4k-SNP as well as between 40-SNP and Cheng’s index were above 0.98 and 0.86, respectively. These results verified the validity and accuracy of 40-SNP on xian-geng identification in Oryza sativa L. In addition, 40-SNP also had a good distinguishability for the six subgroups in rice, and the xian-geng index of indica, aus, rayada, aromatic, tropical japonica, and, temperate japonica was less than 0.20, 0.20-0.40, 0.60-0.85, more than 0.90, and 1.00, respectively. This study provides the data and theoretical basis for the differentiation of xian-geng and the utilization of heterosis and, formulation of seed management regulations.

      Identification, expression profile of soybean PIN-Like (PILS) gene family and its function in symbiotic nitrogen fixation in root nodules
      DONG Yan-Kun, HUANG Ding-Quan, GAO Zhen, CHEN Xu
      Acta Agronomica Sinica. 2022, 48(2):  353-366.  doi:10.3724/SP.J.1006.2022.14006
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      Plant hormone auxin plays a vital role in the growth and development of plants. Auxin homeostasis and concentration gradient establishment control the polar formation of almost all organs. The synthesis, transportation, perception, and metabolic degradation of auxin in specific cells establish a concentration gradient of auxin in accordance with organ development. In legumes, roots interact with soil microorganisms to form a special organ called nodules, which is used for biological nitrogen fixation. However, the function of auxin homeostasis control of biological nitrogen fixation is unknown. Studies showed that PIN-Like (PILS) proteins in Arabidopsis helped to regulate intracellular auxin homeostasis and mediate auxin signal transmission in the downstream nucleus. In this study, 19 PILS family genes (GmPILSs) were identified in soybean genome and distributed unevenly on 10 chromosomes of soybean. GmPILSs exhibited a variety of expression patterns in nine tissue parts of soybean, and had obvious specificity of tissue expression. GmPILS1e and GmPILS1f were enriched and expressed in the rhizobia region, and the expression of GmPILS1e and GmPILS1f in nodules was down-regulated by artificial microRNA interference (amiRNAi), resulting in the increase of nitrogenase activity in the nodules. However, the overexpression of GmPILS1f leaded to the decrease nitrogenase activity in root nodules, GmPILS1e and GmPILS1f might participate in the regulation of soybean nitrogenase activity. These results lay the foundation for further analysis of the function and mechanism of soybean GmPILS family genes, and also provide valuable genetic resources for the application of nodulation and nitrogen fixation in agricultural breeding.

      Identification of salt tolerance and screening of salt tolerant germplasm of mungbean (Vigna radiate L.) at seedling stage
      HU Liang-Liang, WANG Su-Hua, WANG Li-Xia, CHENG Xu-Zhen, CHEN Hong-Lin
      Acta Agronomica Sinica. 2022, 48(2):  367-379.  doi:10.3724/SP.J.1006.2022.04283
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      Soil salinization has become one of the important factors affecting agricultural production in China. It is of great significance to screen germplasm resources of mungbean [Vigna radiate (L.) Wilczek] for the utilization of salinized land. In the present study, the seedlings of 346 domestic and foreign collections of mungbean were exposed to 150 mmol L -1 NaCl. To evaluate the salt-tolerance of different mungbean genotypes at seedling stage, 12 indicators were calculated, including plant height, fresh weight of above-ground part, fresh weight of root, dry weight of above-ground part, dry root weight, root length, and root volume. Salt tolerance of each sample was comprehensively evaluated and classified by principal component analysis, membership function analysis, salt tolerance comprehensive evaluation, and cluster analysis; and the regression equation of salt tolerance prediction was established by stepwise regression analysis. The results revealed that there were significant differences between treatment group and control group in each trait evaluation index, and the salt tolerance coefficients of the 12 indicators were correlated to some content. Combining the classification of salt damage symptoms and the comprehensive evaluation results of salt tolerance, 26 mungbean germplasms with high salt tolerance, 65 germplasms with high salt tolerance, 74 germplasms with salt sensitive, and 18 germplasms with extremely salt sensitive were selected at seedling stage. Among them, 10 varieties such as C04125 from Jiangxi and C06310 from the Philippines had the strongest salt tolerance, which could be used as excellent resources for mungbean salt tolerance breeding. Above-ground fresh weight, root fresh weight, root dry weight, root length, root volume, and root branch number could be used to predict salt tolerance of mungbean at seedling stage.

      QTLs analysis of oil and three main fatty acid contents in cottonseeds
      ZHANG Yan-Bo, WANG Yuan, FENG Gan-Yu, DUAN Hui-Rong, LIU Hai-Ying
      Acta Agronomica Sinica. 2022, 48(2):  380-395.  doi:10.3724/SP.J.1006.2022.04273
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      In this study, in order to uncover more useful gene information for these traits, the analysis of QTLs controlling the contents of oil, palmitic acid, oleic acid, and linoleic acid in cottonseeds was conducted in different genetic systems. Based on a set of 188 recombinant inbred lines (RILs) derived from an intra-specific cross between two upland germplasms HS46 (P1) and MARCABUCAG8US-1-88 (P2), double backcross populations BC (P1) and BC (P2) were constructed in 2017 and 2018, respectively. BC (P1) and BC (P2) populations were obtained through backcrossing each of the two parents (HS46 and MARCABUCAG8US-1-88) with the 188 RILs, respectively. The cottonseeds from these backcross populations were used for QTLs analysis of oil, palmitic acid, oleic acid, and linoleic acid contents. To map QTLs for these traits, the mixed linear genetic model and the QTL Network-CL-2.0-Seed software, which were developed especially for seed traits, were applied. In total, seven QTLs for the oil content, three for the palmitic acid content, two for the oleic acid content, and three for the linoleic acid content were detected. Significant additive effects of QTLs from maternal plants and embryos were detected for all the QTLs. Seven QTLs, each of which explained more than 10% of total phenotypic variation, were found. The detected QTLs in the present study may give us better understanding of the molecular inheritance for these four traits, and provide more reliable information for molecular marker assisted breeding.

      TILLAGE & CULTIVATION·PHYSIOLOGY & BIOCHEMISTRY
      Effects of DPC and nitrogen fertilizer through drip irrigation on growth and yield in cotton
      ZHANG Te, WANG Mi-Feng, ZHAO Qiang
      Acta Agronomica Sinica. 2022, 48(2):  396-409.  doi:10.3724/SP.J.1006.2022.14026
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      In order to explore the effects of DPC (1,1-dimethyl-piperidinium chloride) and nitrogen fertilizer on agronomic traits and clarify the interaction effect of DPC and nitrogen fertilizer through drip irrigation in cotton, we performed a two-factor randomized block design with three nitrogen levels (pure N, N1: 150 kg hm -2, N2: 300 kg hm -2, and N3: 450 kg hm -2) and three DPC levels (D1: 525 g hm -2, D2: 1050 g hm -2, and D3: 2100 g hm -2). These groups interacted with each other and formed nine treatments. The effects of different groups on agronomic traits, the spatial and temporal distribution of boll, the accumulation and distribution of dry matter, yield, and fiber quality were investigated in cotton. The results showed that the interaction between DPC and nitrogen fertilizer had a significant impact on the agronomic traits of cotton; The retarding effect of DPC on cotton growth was weakened or even disappeared under the low nitrogen condition. Under N1 treatment, compared to D1 treatment, plant height, initial node height of fruit branch, length of fourth, and seventh fruit branch of D3 treatment increased by 12.07, 1.54, 1.28, and 1.20 cm, respectively. Under normal or high nitrogen conditions, DPC had a certain retarded effect on cotton growth, but the control effect did not increase with the increasing DPC doses. Under N3 treatment, compared with D1 treatment, the plant height, first fruit branch length, and the average internode length of the second fruit of D3 treatment decreased by 1.05, 1.68, and 1.52 cm, respectively. Plant height, stem diameter, and fruit branch number of cottons increased with the increase of nitrogen application rate. Compared with N1 treatment, N3 treatment increased 3.30 cm, 0.75 mm and 0.29 sets, respectively. There were no significant differences in the length of fruit branch and internode among the different nitrogen application rates. The drip application of D2 treatment was beneficial for dry matter accumulation and translocation to reproductive organs. It promoted pre-ambient and ambient peaches growth, but there was not significant effect on cotton yield and fiber quality. The total dry matter accumulation was 13.14%-44.50% higher in N1 than that in other treatments. The percentage of reproductive organs increased by 2.05%-6.30% compared with N3 treatment. When applying 2100 g hm -2 DPC and 150 kg hm -2 nitrogen fertilizer with water drop, the cotton fiber quality, seed cotton yield, boll number per plant, and boll weight per plant were the highest; and the effect of yield increase was better. In conclusion, we recommended to apply 1050-2100 g hm -2DPC and 150 kg hm -2 nitrogen fertilizer with drip irrigation in the cotton area of northern Xinjiang.

      Nitrogen fertilizer reduction and precise application model on mechanical transplanting japonica rice with good taste quality under straw returning in Huaibei Area
      ZHANG Jun, ZHOU Dong-Dong, XU Ke, LI Bi-Zhong, LIU Zhong-Hong, ZHOU Nian-Bing, FANG Shu-Liang, ZHANG Yong-Jin, TANG Jie, AN Li-Zheng
      Acta Agronomica Sinica. 2022, 48(2):  410-422.  doi:10.3724/SP.J.1006.2022.02093
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      At present, “nitrogen reduction” has become one of the planting measures for good eating quality japonica rice, but the scientific management plan of nitrogen fertilizer after nitrogen reduction is unclear and further studies are needed. From 2018 to 2019, good eating quality japonica rice varieties including Nanjing 505 and Nanjing 2728 were planted as materials, and four ratios of basic and tillering to panicle fertilizer including 5:5, 6:4, 7:3, and 8:2 were arranged with nitrogen application 20% less than conventional nitrogen application (CK) for mechanical transplanting rice under wheat straw returning. Yield, rice quality, and nitrogen utilization were investigated to determine the effects under nitrogen reduction for good eating quality japonica rice. The results were as follows: With the increase of the proportion of the basic and tillering fertilizer in the total nitrogen application, the yield increased first and then decreased. The 7:3 treatment had the highest yield, reaching 11,134.80-11,280.19 kg hm -2 for two years. Compared with CK, the yield increased by 1.23%-2.54% and there was no significant difference. The 7:3 treatment group could obtain sufficient population spikelet, higher seed-setting rate, and 1000-grain weight. With the increase of the proportion of nitrogen application in the previous period, the dry matter weight of the population at (N-n) stage and jointing stage displayed an increasing trend, while the dry matter weight at heading stage and maturity stage, the dry matter accumulation from heading to maturity, the final nitrogen accumulation and the nitrogen efficiency increased first and then decreased, and reached a peak in the 7:3 treatment. Compared with CK, nitrogen reduction treatment could ensure higher dry matter accumulation of the population at the later stage by increasing the proportion of nitrogen fertilizer application (7:3) at the early stage, which significantly improved nitrogen absorption and nitrogen use efficiency of the population by 14.10%-15.48%, and significantly higher than CK. For eating quality of japonica rice under nitrogen reduction, the processing quality deteriorated with the increase proportion of basic and tillering nitrogen, the appearance quality became better, the cooking and eating quality improved, and rice RVA profile was optimized. Under the condition of the whole wheat straw to the field, nitrogen was reduced by 20% compared with conventional fertilization. To achieve the comprehensive planting goal of high-yield, high-quality, and high-efficiency for good eating quality rice to a certain extent, nitrogen application with the ratio of basic and tillering fertilizer to panicle fertilizer 7:3 could stabilize or slightly increase the yield of good eating quality japonica rice, greatly increase nitrogen use efficiency, and improve the appearance and taste quality in rice.

      Variety matching and resource use efficiency of the winter wheat-summer maize “double late” cropping system
      YAN Yan, ZHANG Yu-Shi, LIU Chu-Rong, REN Dan-Yang, LIU Hong-Run, LIU Xue-Qing, ZHANG Ming-Cai, LI Zhao-Hu
      Acta Agronomica Sinica. 2022, 48(2):  423-436.  doi:10.3724/SP.J.1006.2022.11017
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      It is of great significance that exploring the characteristics of wheat-maize varieties combination suitable for stress resistance, high yield, and stable yield under the “double delay” system and their matching properties with natural resources, for ensuring the high yield and high efficiency production of winter wheat and summer maize in this region. In this study, field experiments were conducted from 2017 to 2019. Eight winter wheat and eight summer maize varieties were the main varieties in the North China Plain under winter wheat-summer maize “double delay” system with different irrigation treatments. Based on the analysis and evaluation of water use efficiency, grain filling characteristics, growth process, annual light, temperature, and water use efficiency, etc., the characteristics of wheat-maize varieties combination and resource use efficiency under the “double delay” system of winter wheat and summer maize were explored. The results suggested that among the tested wheat varieties, the yields of Jimai 325, Shimai 15, Nongda 3486, and Jimai 22 under conventional water-saving irrigation and rain-fed mode were higher than the average yield of the tested varieties druing the two growing seasons. In addition, the drought resistance index of Jimai 325 and Shimai 15 were higher than that of Jimai 22. Meanwhile, the grain-filling rate, grain number per spike, grain weight, and high stability coefficients of Jimai 22, Jimai 325, and Shimai 15 were higher than the mean of the tested varieties under different irrigation modes. Among the tested maize variaties, the yield and high stability coefficients of Denghai 605, Weike 702, MC670, and Nonghua 816 were all higher than the means of the tested varieties. The grain-filling rate of MC670, Denghai 605, and Xianyu 335 were higher than the means of the tested varieties during the two growing seasons. While, Dika 517 and Xianyu 335 had the lowest grain water content at harvest stage but the highest average dehydration rate among the tested varieties. Based on the comprehensive analysis of the yield and yield stability, drought resistance, grain-filling properties, and dehydration characteristics, the variety combination of Jimai 325-MC670 was selected with the highest annual yield and resource use efficiency. Compared with the local control combination of Jimai 22-Zhengdan 958, the annual yield increased by 17.2% and 17.9%, the light, temperature and irrigation water use efficiency increased by 18.6% and 20.0%, 18.1% and 18.9%, 17.4% and 18.1%, and increased economic benefit 8800 Yuan hm -2 and 9600 Yuan hm -2, respectively; to fit the whole-process mechanized management mode of wheat-maize double cropping system, maize could use varieties with fast dehydration rate and low grain water content when harvest, such as Dika 517 or Xianyu 335. Compared with the current local combination of Jimai 22-Zhengdan 958, this combination could increase the annual yield by 4.7% and 14.4%, and increase the light, temperature, and irrigation water use efficiency by 5.6% and 16.3%, 4.7% and 15.4%, 5.0% and 14.6%, and increased economic benefit by 2080 Yuan hm -2 and 7080 Yuan hm -2, respectively. In summary, optimizing the wheat-maize variety combination under the “double delay” cropping system can further improve the annual yield and resource use efficiency synergistically compared with the local staple wheat-maize variety combination.

      Effect of water and nitrogen reduction on main photosynthetic physiological parameters of film-mulched maize no-tillage rotation wheat
      XU Long-Long, YIN Wen, HU Fa-Long, FAN Hong, FAN Zhi-Long, ZHAO Cai, YU Ai-Zhong, CHAI Qiang
      Acta Agronomica Sinica. 2022, 48(2):  437-447.  doi:10.3724/SP.J.1006.2022.01093
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      The effect of no-tillage combined with water and nitrogen reduction of mulching maize on the stability and increase of wheat yield has been verified, but the research of the photosynthetic physiological mechanism of its formation is still relatively weak. From 2018 to 2020, the split zone design was adopted, and two farming methods of film-mulched corn no-tillage (NT) and traditional tillage (CT) was arranged with two irrigation levels of traditional irrigation (I2, 2400 m 3 hm ?2) and traditional irrigation reduce 20% (I1, 1920 m 3 hm ?2) and three nitrogen application levels of 225 kg hm ?2 (N3), 180 kg hm ?2 (N2) and 135 kg hm ?2 (N1). The results showed that farming measures and nitrogen application level had significant effects on wheat leaf area index, photosynthetic potential, SPAD value, and photosynthetic rate; irrigation level had significant effects on photosynthetic rate. During the whole growth periods, compared with CT, NT increased wheat leaf area index, photosynthetic potential, SPAD value, and photosynthetic rate by 14.5%-44.1%, 13.2%-16.3%, 7.4%-9.0%, and 14.5%-24.2%, respectively; Compared with I2, the photosynthetic rate of wheat I1 decreased by 6.5%-13.6%. Compared with N3, the leaf area index, photosynthetic potential, SPAD value, and photosynthetic rate of N1 decreased by 6.4%-13.6%, 7.5%-12.7%, 6.0%-10.2%, and 7.5%-17.5%, respectively. There was no significant difference between N2 and N3. Cultivation measures, nitrogen application level, and irrigation level all had significant effects on dry matter accumulation and grain yield in wheat. Compared with CT, NT increased by 13.4%-16.5% and 9.0%-13.4%; Compared with I2, I1 decreased by 6.5%-6.7% and 4.3%-7.4%; Compared with N3, the dry matter accumulation and grain yield of N1 decreased by 10.0%-11.9% and 12.6%-19.4%, respectively, and there was no significant difference between N2 and N3. Correlation matrix analysis showed that the combined water and nitrogen reduction of no-tillage maize mulching could delay the decrease of wheat SPAD value, prolonged the photosynthetic time, and increased the photosynthetic potential and photosynthetic rate of wheat to increase yield.

      Evaluations of winter wheat late frost damage under different water based on principal component-cluster analysis
      WANG Yang-Yang, HE Li, REN De-Chao, DUAN Jian-Zhao, HU Xin, LIU Wan-Dai, GU Tian-Cai, WANG Yong-Hua, FENG Wei
      Acta Agronomica Sinica. 2022, 48(2):  448-462.  doi:10.3724/SP.J.1006.2022.11003
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      To investigate the effect of low temperature at jointing stage on wheat physiological metabolism under different water conditions, a comprehensive physiological index is constructed to accurately evaluate the degree of freezing injury, which is of great significance to agricultural loss reduction, efficiency increase and macro management. Irrigation (W1) and no irrigation (W0) treatments were carried out one week before low temperature treatment using the weak-spring Yanzhan 4110 and Lankao 198, semi-winter Zhengmai 366 and Fengdecun 21 as the experimental materials. At the female and male ear differentiation stages, potted wheat was moved to the low temperature simulation room for low temperature treatment with six levels of normal (CK), -2℃ (T1), -4℃ (T2), -6℃ (T3), -8℃ (T4), and -10℃ (T5), respectively. The physiological indexes and fluorescence parameters were measured on the second day after treatment, and wheat yield was harvested at maturity stage. The results revealed that different varieties, water and low temperature stress, and their interactions had significant effects on wheat physiological indexes and fluorescence parameters at jointing stage. With the aggravation of low temperature stress, leaf water content, chlorophyll a content and fluorescence parameters qp, Fv/Fm, and Fv/Fo showed the continuous downward trends, the contents of soluble protein, proline, soluble sugar, and SOD activity first increased and then decreased, but the content of MDA demonstrated the opposite trend. Irrigation treatment alleviated the influence of low temperature stress on plant physiological metabolism, and the effect of low temperature on semi-winter varieties was relatively lower. Four independent comprehensive indexes were transformed by the principal component analysis, which reflected 88.55% of the original information, and the physiological comprehensive index of freezing injury (FICEI) was constructed. The depth of color in heat map indicated the darker the color, the greater the performance degree of indicators. According to the FIPCI value, the freezing injury was divided into five levels, which was consistent with the yield loss rate. Especially under T3 treatment, the yield loss rate of each variety reduced by 30.4%-44.0% under no irrigation, reduced by 21.0%-29.2% under irrigation treatment. Under the same irrigation condition, yield loss rate of different varieties was LK198>YZ4110>ZM366>FDC21, and the yield loss rate of semi-winter varieties was lower than that of weak spring varieties. According to the results of heat map clustering and the yield of each treatment, the yield loss rate was less than 10% for CK and T1, 10%-30% for W0T2, W1T2 and W1T3, 30%-50% for W0T3 and W1T4, more than 50% for W0T4, W0T5 and W1T5. Irrigating before low temperature was conducive to alleviating the damage caused by low temperature stress and reducing the yield loss. Physiological comprehensive freezing injury index and model constructed by principal component-cluster analysis can accurately evaluate the degree of wheat late frost damage, and provide scientific basis for yield recovery and decision-making management after disaster.

      Effects of nitrogen rate on growth, grain yield, and nitrogen utilization of multiple cropping proso millet after spring-wheat in Irrigation Area of Ningxia
      XIE Cheng-Hui, MA Hai-Zhao, XU Hong-Wei, XU Xi-Yang, RUAN Guo-Bing, GUO Zheng-Yan, NING Yong-Pei, FENG Yong-Zhong, YANG Gai-He, REN Guang-Xin
      Acta Agronomica Sinica. 2022, 48(2):  463-477.  doi:10.3724/SP.J.1006.2022.14010
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      The objective of this study is to clarify the growth rule, yield, and nitrogen utilization efficiency of proso millet under different nitrogen rates, the relationship between morphological characteristics and grain yield and nitrogen utilization was explored, and the suitable nitrogen rate for multiple cropping proso millet after spring-wheat in Irrigation Area of Ningxia was determined. The field experiments were conducted by single factor randomized block design, with four nitrogen rates [0 (N0), 90 (N1), 120 (N2), and 150 kg hm -2 (N3)] were set in 2019, and six nitrogen rates [180 (N4) and 210 kg hm -2 (N5) were added] in 2020. The results showed that the plant height, stem diameter, leaf area, root morphology, and dry matter accumulation at the key growth stages of proso millet were significantly promoted by nitrogen application, however, nitrogen application rate exceeded 150 kg hm -2, these indexes declined slightly except for the stem diameter and leaf area. With the increase of nitrogen rate, the root-shoot ratio decreased first and then increased and then decreased slightly, and it reached the minimum under N2 treatment at most growth stages. The root-shoot ratio at jointing, heading, grain-filling and maturity stage under N2 treatment were 0.119, 0.087, 0.054, and 0.052, respectively. The grain yield, 1000-grain weight, and grain number per plant were significantly increased by nitrogen application, and with the increase of nitrogen application rate, the yield increased initially then slightly decreased, and achieved the best effect in N2 and N3 treatments. The grain yields of N2 and N3 treatments were 2979.41 kg hm -2 and 3084.67 kg hm -2, respectively, which were 76.22% and 83.21% higher than those of N0 treatment. Nitrogen harvest index (NHI), nitrogen fertilizer apparent recovery rate (NRE), agronomic efficiency (NAE), and partial productivity (NPFP) under N2 treatment were 60.23%, 61.81%, 10.77 kg kg -1, and 24.83 kg kg -1, respectively. Furthermore, grain yield was significantly positively correlated with each growth index, and there was significant positive correlation between each growth index, and the root morphological characteristics were significantly positively correlated with nitrogen accumulation. These results revealed that nitrogen application could improve the root morphological characteristics of proso millet to promote the absorption of nitrogen, and further promote the growth of canopy, which was conductive to yield formation. In view of the growth, grain yield and nitrogen utilization, the reasonable nitrogen rate for multiple cropping proso millet in Irrigation Area of Ningxia was 120-150 kg hm -2.

      Effects of water deficit on physiology and biochemistry of seedlings of different wheat varieties and the alleviation effect of exogenous application of 5-aminolevulinic acid
      CHEN Xin-Yi, SONG Yu-Hang, ZHANG Meng-Han, LI Xiao-Yan, LI Hua, WANG Yue-Xia, QI Xue-Li
      Acta Agronomica Sinica. 2022, 48(2):  478-487.  doi:10.3724/SP.J.1006.2022.11026
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      Drought stress happens frequently in Huang-Huai winter wheat planted area, causing severe injury on photosynthetic apparatus of wheat seedlings. To characterize the traits of photosynthetic physiology in different wheat cultivars in response to water deficit, the newly in-lab cultivated Zhengmai 1860, as well as Bainong 207 and Zhoumai 18 were used as materials in this study. We explored the effects of water deficit on photosynthetic traits, antioxidant enzyme activities, and related gene transcription of seedlings in different cultivars, as well as the drought alleviation effect of exogenous application of 5-aminolevulinic acid (ALA). The results were as follows: Zhengmai 1860 had comparatively higher root dry weight and root shoot ratio than the other two cultivars under drought stress. Compared to Zhoumai 18, the drought resistant cultivars (Zhengmai 1860 and Bainong 207) had lower reduction in chlorophyll content and increased MDA content, enhanced the activities of SOD and CAT, and lowered reductions in chlorophyll fluorescence parameters and the photosynthetic parameters. Meanwhile, water deficit obviously improved the transcriptions of antioxidant enzyme-encoded genes CAT, SOD-Cu/Zn, MnSO, and FeSOD, which showed a correlation between the increasing level with the drought resistant ability. The exogenous pretreatment of ALA further enhanced the activities of SOD and CAT to lower the damage to membrane lipid peroxidation by inducing the transcriptions of CAT, SOD-Cu/Zn, and MnSOD. ATPase activity was also increased to alleviate water deficit on the damage to photosynthetic physiology. Moreover, we found for the first time that the transcriptional maintenance of chloroplast photosynthetic apparatus related psb28 gene had a correlation with the drought resistance between different wheat cultivars, which was also significantly induced by the exogenously pretreated ALA. These results in this study proposed that the transcriptions of antioxidant enzymes and chloroplast photosynthesis related genes had a close relationship with the drought resistant ability of wheat and the alleviation effect of exogenous ALA in wheat.

      Construction and application of the critical nitrogen concentration dilution model of sugar beet in Inner Mongolia, China
      ZHANG Jia-Kang, LI Fei, SHI Shu-De, YANG Hai-Bo
      Acta Agronomica Sinica. 2022, 48(2):  488-496.  doi:10.3724/SP.J.1006.2022.04272
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      Sugar beet is one of the two major sugar crops in China. However, both nitrogen sufficiency and deficiency will affect the yield and sugar content in sugar beet, and excessive nitrogen will cause environmental risks. Judging nitrogen nutrition of sugar beet in a reasonable range is of great significance for ensuring the yield, quality and reducing environmental risks of sugar beet. The critical nitrogen concentration dilution curve is the basis of crop nitrogen nutrition diagnosis. The objective of this present study was establishing the dilution curve model of the critical nitrogen concentration of sugar beet in China and to diagnose the nitrogen nutrition of sugar beet by using the corresponding nitrogen nutrient index. Four experiments with different N rates for two cultivars of sugar beet were conducted in Inner Mongolia from 2017 to 2018. The above-ground biomass and under-ground tubers were sampled and their nitrogen concentration was determined at seedling, leaf cluster growth, tuber bulking, sugar accumulation, and harvest stages. The total plant biomass and nitrogen concentration were calculated. Based on the calculation, the critical nitrogen concentration dilution model and the corresponding nitrogen nutrient index were established. The results indicated that the negative power relationship between the above-ground biomass and nitrogen concentration was observed. The determination coefficient (R 2) for the relationship was 0.45 on average. The R 2 for the negative power relationship between total plant biomass and nitrogen concentration was 0.94 on average, which was higher than the relationship between the above-ground biomass and nitrogen concentration. It was more reasonable to establish a critical nitrogen concentration dilution model based on the total plant biomass and nitrogen concentration, which was less affected by the cultivars. The R 2 for the integrated critical nitrogen concentration dilution curve of sugar beet varieties KWS9167 and KWS1676 reached 0.94. The constructed nitrogen nutrition model can be used to estimate the plant nitrogen status in sugar beet. The critical nitrogen concentration dilution model for the main sugar beet varieties in Northern China was Nc = 4.23W -0.49. The optimized nitrogen rate of KWS9167 and KWS1676 based on the model was about 160 kg hm -2 and 180 kg hm -2, respectively.

      Coupling effects of irrigation and nitrogen levels on yield, water distribution and nitrate nitrogen residue of machine-harvested cotton
      ER Chen, LIN Tao, XIA Wen, ZHANG Hao, XU Gao-Yu, TANG Qiu-Xiang
      Acta Agronomica Sinica. 2022, 48(2):  497-510.  doi:10.3724/SP.J.1006.2022.04277
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      The shortage of water resources and the excessive investment of fertilizer are the bottlenecks that restrict the sustainable and healthy development of agriculture and force farmers to develop and adopt sustainable production technologies. The mechanism of water movement and the residual behavior of nitrogen fertilizer are important scientific issues to evaluate the level of agricultural water and fertilizer management in arid areas. Improving the water and nitrogen utilization efficiency was an important way to reduce environmental pollution. An experiment was conducted using a split plot design with the main area for total irrigation of 2250 (W1, non-sufficient drip irrigation), 3450 (W2, conventional drip irrigation), 4650 m 3 hm -2 (W3, saturated drip irrigation), and the deputy area of nitrogen (pure N) including 0 (N1, no fertilizer), 300 (N2, conventional fertilization), 600 kg hm -2 (N3, excess fertilization) in arid area of northwest China cotton region from 2018 to 2019. The effects of irrigation and nitrogen levels on water distribution, nitrate nitrogen residue, seed cotton, irrigation water, and N fertilizer productive efficiency were evaluated. The results revealed that irrigation and coupling effects of irrigation and nitrogen levels were the influencing factors on seed cotton and water utilization efficiency, among which irrigation was the main effect. Two-year average values demonstrated that the irrigation was W1, nitrogen fertilization amount increased from N1 to N3, and the average soil moisture content of 0-80 cm during the whole growth period increased first and then decreased. Compared with N1 fertilization application, seed cotton yield was 13.8% and 7.6% higher and irrigation water productive efficiency were 13.6% and 6.8% higher under N2 and N3 fertilization application, respectively. When the irrigation was W2 and W3, the nitrogen fertilization amount increased from N1 to N3, and there was no significant difference in the average soil moisture content of 0-80 cm during the whole growth period. Compared with N1 fertilization application, seed cotton yield was 11.4% and 11.5% higher and irrigation water productive efficiency were 13.6% and 6.8% higher under N2 and N3 fertilization application, respectively. With the increase of irrigation, the total average value of 0-80 cm during the whole growth period gradually increased. Irrigation was the main effect on soil nitrate nitrogen accumulation in the main distribution area of 0-40 cm roots, and coupling effects of irrigation and nitrogen levels was the main factor leading to nitrate nitrogen leaching. When the irrigation was W1, nitrate nitrogen accumulated in the 0-40 cm with the increase of nitrogen. And when the irrigation was W3, nitrate nitrogen accumulated in the 40-60 cm with the increase of nitrogen. In conclusion, if the irrigation was higher than 3450 m 3 hm -2 and nitrogen was higher than 300 kg hm -2, the continued increase of water and nitrogen input failed to increase production, which might result in resource waste and potential pollution to the environment. Therefore, we suggest that water and nitrogen optimization strategies can improve resource utilization efficiency, reduce water and fertilizer input, and healthy development of agriculture.

      RESEARCH NOTES
      Molecular cytogenetic identification of wheat-Thinopyrum intermedium 2A/6St substitution strain 014-459
      TAO Jun, LAN Xiu-Jin
      Acta Agronomica Sinica. 2022, 48(2):  511-517.  doi:10.3724/SP.J.1006.2022.11025
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      Thinopyrum intermedium is a valuable resource for wheat genetic improvement, and numerous wheat-Th. intermedium chromosome addition and substitution lines and partial amphiploids have been developed. Zhong 4 is a wheat-Th. intermedium partial amphidiploid, which can easily hybridize with wheat and is extensively utilized for wheat improvement. The strain 014-459 was a progeny of partial amphidiploid Zhong 4 descendant of wheat and Th. intermedium with some special characteristics such as high crude protein and wet gluten content and partial F1 of common wheat cultivars and strain 014-459 were sterility while a few others were fertility despite reciprocal cross. Molecular cytogenetic identification of strain 014-459 were detected for speculated contained fragment of Th. intermedium chromosomes based on its special characters. Genomic composition of strain 014-459 was detected by FISH, GISH, and PLUG (polymerase chain reaction-based landmark unique gene) marker analysis. Combined FISH/GISH analysis confirmed that a pair of wheat 2A chromosomes in strain 014-459 of the hybrid progeny between wheat-Thinopyrum intermedium partial amphidiploid Zhong 4 and wheat was replaced by a pair of St chromosomes from Thinopyrum intermedium. PLUG marker analysis verified that this pair belonged to the sixth homologous group. The special characters of strain 014-459 might be attributable to the substitution of Th. intermedium St chromosome into wheat. The study of molecular cytogenetic identification of strain 014-459 was probably beneficial to quality improvement and utilization of 6St chromosome of Th. intermedium in wheat breeding.

      Screening of leaf physiological characteristics and drought-tolerant indexes of sweetpotato cultivars with drought resistance
      ZHANG Hai-Yan, XIE Bei-Tao, JIANG Chang-Song, FENG Xiang-Yang, ZHANG Qiao, DONG Shun-Xu, WANG Bao-Qing, ZHANG Li-Ming, QIN Zhen, DUAN Wen-Xue
      Acta Agronomica Sinica. 2022, 48(2):  518-528.  doi:10.3724/SP.J.1006.2022.14031
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      Field experiments were conducted under a rain proof shelter using 15 sweetpotato cultivars with well-watered and drought stress treatments. Leaf physiological characteristics of different sweetpotato cultivars under drought stress were studied. The results showed that the leaf area index of all varieties decreased in different degrees under drought stress, which evaluating the difference of drought tolerance in varieties. Cluster analysis of drought resistance coefficient revealed that 15 sweetpotato cultivars were classified into three drought resistant types. The drought-tolerant cultivars were Jishu 21, Jishu 25, Jixu 23, Jishu 15, and Yanshu 25. The moderate drought-tolerant cultivars were Xushu 18, Jishu 26, Beijing 553, Jizishu 2, and Jishu 18. The drought-sensitive cultivars were Zhengshu 20, Jizishu 3, Jishu 22, Jizishu 1, and Ayamaraski. The correlation analysis between leaf area index and drought resistance coefficient demonstrated that the drought-tolerant cultivars could maintain higher leaf area index under drought stress, while the leaf area index under well-watered could not reflect the drought resistance. Drought stress resulted in the decline of chlorophyll content, the relative water content of functional leaves, and the increase of relative electrical conductivity of functional leaves. Under drought stress, the chlorophyll content and relative water content of functional leaves were significantly positively correlated with drought resistance in different cultivars, while the relative electrical conductivity of functional leaves was significantly negatively correlated with the drought resistance of sweetpotato varieties. In summary, leaf area index, chlorophyll content, relative water content, and relative electrical conductivity of functional leaves could be used as comprehensive evaluation indexes for identifying drought resistance of sweetpotato cultivars.

      Effects of sink-limiting treatments on leaf carbon metabolism in soybean
      ZHANG Guo-Wei, LI Kai, LI Si-Jia, WANG Xiao-Jing, YANG Chang-Qin, LIU Rui-Xian
      Acta Agronomica Sinica. 2022, 48(2):  529-537.  doi:10.3724/SP.J.1006.2022.14024
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      Carbon metabolism is one of the most obvious physiological processes affected by source-sink relationship, which is closely related to plant growth and yield formation. The study of the effect of sink-limiting treatment on carbon metabolism of soybean leaf can provide a theoretical basis for understanding yield reduction mechanism caused by the imbalance of source-sink relationship. Taking early maturing soybean Sudou 13 as materials, pool experiments were carried out at the soybean experimental station of Jiangsu Academy of Agricultural Sciences in 2019 and 2020. The sink-limiting treatments (all pods removal, 1/2 pods removal, and all seed injury) were conducted at R4 stage, and intact (fully podded) plants were used as control. The results showed that sink-limiting treatments delayed leaf senescence and abscission and caused stay-green. Sink-limiting treatments inhibited the net photosynthetic rate (Pn) in a short time after treatment, but did not affect the initial carboxylation rate (ɑ), and the decrease of Pn was mainly restricted by stomata limitation. With the prolongation of the time after treatment, the inhibition effect on photosynthesis gradually weakened and turned into a promoting effect. At late growth stages, the stay-green syndrome leaves still maintain relatively higher initial carboxylation rate (a), sugar phosphate synthase (SPS), sucrose synthase (SuSy), acid invertase (SAI) activity, photosynthetic pigment, soluble sugar, starch, sucrose, and fructose content, which was beneficial to maintaining a relatively high photosynthetic performance. Sink-limiting treatments induced more photosynthetic products to be distributed to vegetative organs, and stimulated stems and leaves to be new sink organs in certain extent, which was beneficial to the output of photosynthetic products and maintained relatively high levels of carbon metabolism of leaves at late growth stages. The effects of removing all pods and seed injury treatments on delaying leaf senescence and abscission, reducing photosynthetic performance and carbon metabolism was significantly higher than those of removing 1/2 pod. In conclusion, sink-limiting under the same source condition could induce stay-green syndrome. The greater the degree of sink-limiting, the more severe the green retention. Sink-limiting treatment significantly affected the carbon metabolism of soybean plant, although it inhibited photosynthetic performance in a short period after treatment. It maintained higher photosynthetic and key enzyme activities of carbon metabolism at late growth stages, which was conducive to the synthesis of more carbohydrates and stimulated the stems, leaves, and petioles to transform into new sink organs to a certain extent.

Co-sponsored:
the Crop Science Society of China
the Institute of Crop Science, CAAS
China Science Publishing & Media Ltd.
Published: Science Press
Editor-in-chief: Wan Jian-min
Associate Editors-in-Chief:
Chen Xiao-ya Yang Jian-chang Zhang Xian-long Wang Jian-kang Xu Ming-liang Liu Chun-ming Wang Dao-wen Sun Chuan-qing Ding Yan-feng Jin Wei-wei Chu Cheng-cai Cheng Wei-hong
Director of the editorial department:
Yan Chun-ling
CN 11-1809/S
ISSN 0496-3490
Post subscription code: 82-336

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  • Started in 2013
  • Covered by SCIE
  • Open access in ScienceDirect

Editor in chief: Wan Jian-min
CN 10-1112/S
ISSN 2095-5421, 2214-5141(online)
Online published:
https://www.sciencedirect.com/journal/the-crop-journal
Submission: https://www.editorialmanager.com/cj/
E-mail: cropjournal@caas.cn
Tel: 8610-82108548

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