Table of Content

12 March 2021, Volume 47 Issue 3

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CROP GENETICS & BREEDING·GERMPLASM RESOURCES·MOLECULAR GENETICS

Genetic analysis and molecular characterization of multilocular trait in the srb mutant of Brassica rapa L.

YANG Yang, LI Huai-Lin, HU Li-Min, FAN Chu-Chuan, ZHOU Yong-Ming

Acta Agronomica Sinica. 2021, 47(3):  385-393.  doi:10.3724/SP.J.1006.2021.04123

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Multilocular silique is considered as a trait associated with high yield in rapeseed, and we studied the genetic regulation of the multilocular trait in B. rapa var. srb. This mutant showed a stable multilocular phenotype, ranging from 94.7% to 100% multilocular siliques per plant and 3.5 carpels per silique. Genetic analyses showed that the multilocular trait was monogenically governed by a recessive nuclear gene. Comparative sequencing analysis revealed that there was a novel C-to-G single-nucleotide mutation in the core CLE motif of BrCLV3, leading to histidine mutation at position 12 in conserved domain to aspartic acid, which was named Brclv3_Asp12. The analysis of segregated population by SNP marker showed that the C/G single-nucleotide variation in Brclv3_Asp12 was co-segregated with the multilocular phenotype. Transgenic complementation studies and in vitro peptide assays further confirmed that the Brclv3_Asp12 allelic mutation in srb could lead to reduced activity of the CLV3 peptide, resulting in the formation of multilocular phenotype. Therefore, the study preliminarily clarified the mechanism involved in multilocular silique formation in srb mutant.

Genome-wide association study of nitrogen use efficiency related traits in common wheat (Triticum aestivum L.)

JIN Yi-Rong, LIU Jin-Dong, LIU Cai-Yun, JIA De-Xin, LIU Peng, WANG Ya-Mei

Acta Agronomica Sinica. 2021, 47(3):  394-404.  doi:10.3724/SP.J.1006.2021.01024

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Nitrogen application plays an important role in plant growth and development. Exploring genetic loci related to nitrogen use efficiency is of great significance for improving wheat yield and reducing environmental pollution. Root system architecture (RSA) determined the composition of plant root system, and significantly affected by nitrogen level. Under different nitrogen levels (deficiency and normal), 160 winter wheat accessions from the Huanghuai valley and Northern winter wheat region were counted for their root architecture-related traits (total root length, total root surface area, total root volume, average root diameter, and root tip number). Genotype was analyzed using 660K SNP (single nucleotide polymorphism) data. Genome-wide association study (GWAS) was employed to identify the relevant loci for nitrogen use efficiency. A total of 34 associated loci were detected, which explained 6.9%-15.4% of the phenotypic variation. These loci distributed on all chromosomes and mainly centered on chromosomes 1A, 2B, 3B, 5B, 6A, 6B, and 7A, respectively. Among the loci detected in this study, 11 loci overlapped or were close to the reported ones, while the other 23 might be novel loci. In addition, we explored a candidate gene encoding the E3 ubiquitin ligase. This study is of great significance for understanding the genetic mechanism of nitrogen utilization and breeding high-yield wheat varieties.

Cloning and potential function analysis of ascorbic peroxidase gene of hybrid wheat in seed aging

YUE Jie-Ru, BAI Jian-Fang, ZHANG Feng-Ting, GUO Li-Ping, YUAN Shao-Hua, LI Yan-Mei, ZHANG Sheng-Quan, ZHAO Chang-Ping, ZHANG Li-Ping

Acta Agronomica Sinica. 2021, 47(3):  405-415.  doi:10.3724/SP.J.1006.2021.01049

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In this study, the seeds of two-line hybrid wheat of BS-type BS1453/11GF5135 and its parents BS1453 (female parent) and 11GF5135 (male parent) were used as materials, and the ascorbate peroxidase gene (TaAPX) was obtained by homologous cloning in BS1453/11GF5135. The gene contains an open reading frame (ORF) of 832 bp, which encoded a total of 277 amino acids. The interaction between miRNAs and TaAPX was predicted by bioinformatics analysis, and the results showed that TaAPX may be regulated by miR396 and other miRNAs that related to stress resistance and seed viability. In addition, it was found that APX protein mainly interacted with redox-related enzymes via protein interaction prediction analysis. qPCR and enzyme activity analysis were conducted on embryos of parents and hybrid at different aging time, it was found that the expression trend of TaAPX gene in hybrid and parents were first up-regulated and then down-regulated. However, the expression of TaAPX gene in hybrid seeds peaked on the seventh day, and it began to decline in parents seeds on the fifth day. There was an antagonistic effect between miR396 and TaAPX. With the increase of aging time, the activity of APX enzyme in parents seeds showed a downtrends, while it showed a temporary downtrends on the third day in hybrid seeds, then it increased and began to decline on the ninth day. It was suggested that the ability of APX enzyme to remove peroxides in the hybrid seeds was higher than that in the parents seeds under the aging condition, that is, the anti-aging ability of hybrid was higher than that of the parents. Moreover, the regulation of seed activity by TaAPX gene was a complex multi-factor regulation process. This study laid a foundation for the further research on the molecular regulation mechanism of the seed vigor of BS type hybrid wheat.

Bioinformatics analysis of SnRK gene family and its relation with seed oil content of Brassica napus L.

TANG Jing-Quan, WANG Nan, GAO Jie, LIU Ting-Ting, WEN Jing, YI Bin, TU Jin-Xing, FU Ting-Dong, SHEN Jin-Xiong

Acta Agronomica Sinica. 2021, 47(3):  416-426.  doi:10.3724/SP.J.1006.2021.04108

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Sucrose non-fermenting-1-related protein kinase (SnRK) is a widely existed serine/threonine protein kinase in plants, which is involved in the regulation of biological processes such as signal transduction, stress response and seed growth. In order to explore the mechamism of the SnRK gene families and its influence on the seed oil content of Brassica napus L., BnSnRK gene family system evolution, gene structure, physical and chemical properties of protein, conservative motif, protein secondary structure, cis-element and subcellular localization prediction were analyzed, and BnSnRK genes affecting oil content of seeds were screened by candidate genes association analysis, haplotype analysis and qRT-PCR. The results showed that 92 BnSnRK members were identified and divided into three subgroups, distributed on 19 chromosomes of Brassica napus L. The physical and chemical properties of proteins were significantly different among subgroups. Most genes had 7-14 exons; the motifs of the same subfamily were more similar in distribution. The BnSnRK family was mainly expressed in the cytoplasm. 12 family members related to the oil content were screened out by association analysis in rapeseed. Genes BnaC02g10730D might negatively regulate seed oil content, while genes BnaA07g12290D, BnaA10g22850D, BnaA08g18050D, and BnaC04g44390D might positively regulate seed oil content of Brassica napus L. There were significant differences in seed oil content under different environments, and 12 oil-related members all contained MYB, MYC and ABA response elements. Environment-specific oil-related genes might be related to plant abiotic stress response. This study provides a theoretical basis for BnSnRK gene functional verification and breeding.

Efficient screening system of effective sgRNA for cotton CRISPR/Cas9 gene editing

ZHOU Guan-Tong, LEI Jian-Feng, DAI Pei-Hong, LIU Chao, LI Yue, LIU Xiao-Dong

Acta Agronomica Sinica. 2021, 47(3):  427-437.  doi:10.3724/SP.J.1006.2021.04178

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Single guide RNA (sgRNA) is one of the important elements of the CRISPR/Cas9 genome editing technology system. However, studies have shown that many sgRNAs cannot work effectively. It is worth screening to verify the effectiveness of multiple design candidate sgRNAs. Instantaneous transformation of protoplasts or leaves with complete editing vectors were used to verification of the effectiveness of sgRNA in the early stage. These methods are time-consuming and laborious, and the success rate is not high, especially for cotton with low efficiency of the protoplasmic system. In this study, target sequences were designed for GhMAPKKK2 and GhAE genes, and two vectors of GhU6-5P::MAPKKK2-sgRNA-1300, GhU6-5P::AE-sgRNA-1300 which transcibed only sgRNA were constructed and injected YZ-1 Cas9 transgenic cotton plant leaves through Agrobacterium; meanwhile, two corresponding complete CRISPR/Cas9 genome editing vectors of GhU6-5P::MAPKKK2-sgRNA-Cas9 and GhU6-5P::AE-sgRNA-Cas9 were constructed and injected YZ-1 wild-type cotton leaves with Agrobacterium. In addition, target sequences were designed for GhPDS, GhCLA1, GhMAPKKK2, and GhAE genes, respectively, and GhU6-5P-2::PDS-sgRNA- CLCrVA, GhU6-5P-2::CLA1-sgRNA-CLCrVA, GhU6-5P-2::MAPKKK2-sgRNA-CLCrVA and GhU6-5P-2::AE-sgRNA-CLCrVA virus delivery vectors were constructed and injected YZ-1 Cas9 transgenic cotton plant leaves through Agrobacterium. In the above experiments, the plants transformed with the empty vector were used as controls. The genomic DNA of the transformed cotton leaves was subjected to PCR and enzyme digestion, and the PCR products which were not completely digested were cloned and sequenced. The results showed that no mutation in target gene was detected in the cotton plants transformed with the GhU6-5P::AE-sgRNA-1300, GhU6-5P::MAPKKK2-sgRNA-Cas9 and GhU6-5P::AE-sgRNA-Cas9, and the target genes mutation in the Cas9 transgenic plants transformed with GhU6-5P::MAPKKK2-sgRNA-1300, GhU6-5P-2::PDS-sgRNA-CLCrVA, GhU6-5P-2::CLA1-sgRNA-CLCrVA, GhU6-5P-2::MAPKKK2-sgRNA-CLCrVA and GhU6-5P-2::AE-sgRNA-CLCrVA vector was uncovered. The types of mutations included base substitution, base deletion and base insertion. The results indicated that the strategy of using Cas9 transgenic plants as transformation recipients can efficiently and truly verify the effectiveness of sgRNA, which eliminated false negative results due to low transformation efficiency, and the strategy of using virus as vectors to deliver sgRNA was more efficient and accurate. The establishment of this sgRNA high-efficiency verification system provides an important technical basis for cotton functional genomics research.

Association analysis of drought tolerance traits of upland cotton accessions (Gossypium hirsutum L.)

HAN Bei, WANG Xu-Wen, LI Bao-Qi, YU Yu, TIAN Qin, YANG Xi-Yan

Acta Agronomica Sinica. 2021, 47(3):  438-450.  doi:10.3724/SP.J.1006.2021.04063

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Drought stress is an important factor that leads to severe reduction in cotton fiber yield and quality worldwide, and new cotton varieties with high-yield, high-quality and drought-tolerant characteristics have been the goal for cotton breeding. In this study, 217 upland cotton accessions were selected for drought stress experiments and association study. The drought stress treatment panels were supplied with 50% the water volume of the controls, until the seedlings emerged. A total of 18 traits including agronomic traits, fiber yield indices and fiber quality indices, were investigated at two locations and for two years. After drought stress, there were significant differences in response between populations, and significant differences in phenotypic traits between control and treatments. The phenotypic data were analyzed by BLUP, and the drought resistance coefficient of each trait was calculated. A total of 393 loci were detected by 214 SSR marker in the tested cotton accessions. The average gene diversity coefficient was 0.402, with the range of 0.072-0.631; and the average PIC value was 0.329, ranging from 0.070 to 0.560. Genetic structure analysis showed that the group could be divided into two subgroups and it had no obvious correspondence with geographical origin. There were detected extremely 76 significant loci (P < 0.01), with explanation rate ranging from 2.931% to 7.218%, by association study using drought resistance coefficient (DRC) of 18 traits. Fourteen SSR marker could be detected by two or more traits at the same time. These results could provide a theoretical basis and reference for the parents selection and drought-resistant molecular marker-assisted breeding in cotton.

Identification of an excellent rice chromosome segment substitution line Z746 and QTL mapping and verification of important agronomic traits

SHEN Wen-Qiang, ZHAO Bing-Bing, YU Guo-Ling, LI Feng-Fei, ZHU Xiao-Yan, MA Fu-Ying, LI Yun-Feng, HE Guang-Hua, ZHAO Fang-Ming

Acta Agronomica Sinica. 2021, 47(3):  451-461.  doi:10.3724/SP.J.1006.2021.92002

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The important agronomic traits, such as grain type, plant height, and panicle composition, are closely related to rice yield, and their gene inheritance is complex. Chromosome segment substitution lines (CSSLs) are useful materials for studying these complex traits. An excellent CSSL, Z746, containing seven substitution segments and with an average substitution length of 3.99 Mb, was identified from Nipponbare as a recipient and ‘Xihui 18’ as a donor parent. There were significant differences in plant height, panicle composition and grain size between Z746 and Nipponbare. Furthermore, a total of 36 quantitative trait loci (QTL) were detected on chromosomes 2, 3, 4, 6, and 11 in the secondary F₂ population constructed by hybridization between Nipponbare and Z746. Five of them may be alleles of the cloned genes, such as qPH3-1, and eight can be detected by multiple times, indicating that these were genetically stable major QTLs. The grain length in Z746 was mainly controlled by four QTLs (qGL3, qGL4, qGL2, and qGL6), and the phenotypic variation of qGL3 and qGL4 for grain length was 60.28% and 27.47%, respectively. Plant height was controlled by five QTLs, panicle length by four QTLs, grain number per panicle by two QTLs, and the 1000-grain weight by two QTLs. Eight single segment substitution lines (SSSLs) were developed in F₃ population by molecular marker-assisted selection (MAS), and relevant QTLs verification was conducted in F₄. Finally, 24 QTLs were detected by 8 SSSLs and the repeat detection rate was 66.7%, indicating that these QTLs were genetically stable. These results provide a good foundation for further research on genetic mechanisms of the target QTLs and molecular design breeding.

QTL mapping of salt and drought tolerance related traits in Brassica napus L.

MENG Jiang-Yu, LIANG Guang-Wei, HE Ya-Jun, QIAN Wei

Acta Agronomica Sinica. 2021, 47(3):  462-471.  doi:10.3724/SP.J.1006.2021.04034

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Salt and drought stresses are main abiotic stresses affecting crop yield. Detecting the QTLs related to salt and drought tolerance can provide theoretical basis for stress resistance breeding in rapeseed. In this study, a doubled haploid population (DH population), which included 261 lines constructed using the German winter rapeseed cultivar ‘Express’ (female) and the Chinese semi-winter line ‘SWU07’ (male), were used to detect QTLs related to salt and drought tolerance. The seeds were germinated in Petri dishes under 1.2% NaCl and 20% PEG-6000, respectively. The control was under the sterile dH₂O. Three tolerance related traits, root length, fresh weight and germination rate of each line were measured on the 7th day after planting. The relative value of root length, fresh weight and germination rate under the salt and drought tolerance condition were calculated. Composite interval mapping (CIM) was used to identify the related QTLs according to the constructed genetic map. A total of 12 QTLs were detected for salt tolerance related traits and located on A02, A03, A05, A09, C01, and C09 chromosome, explaining phenotypic variation ranging from 3.61% to 10.59%. Five of these QTLs were persistently expressed in different repetitions. A total of 9 QTLs were detected for drought tolerance related traits and located on A01, A02, A03, A05, A09, A10, and C03 chromosome, explaining phenotypic variation ranging from 3.94% to 12.90%. Two of these QTLs were persistently expressed in different repetitions. In addition, the overlapped QTLs, located on A02 and A03, were detected under salt stress and drought stress. These results provide more genetic information for improving salt and drought tolerance in rapeseed.

Functional analysis of plasma membrane intrinsic protein ZmPIP1;1 involved in drought tolerance and photosynthesis in maize

ZHOU Lian, LIU Chao-Xian, XIONG Yu-Han, ZHOU Jing, CAI Yi-Lin

Acta Agronomica Sinica. 2021, 47(3):  472-480.  doi:10.3724/SP.J.1006.2021.03027

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Plasma membrane intrinsic protein (PIP) is one of the main subfamily of aquaporin regulates diverse physiology functions during plant growth and development. In previous research, the expression of ZmPIP1;1 was induced by osmosis or salt stress. However, the biological function of ZmPIP1;1 was still unclear in maize. In this study, ZmPIP1;1 overexpressed transgenic plants were obtained and exhibited less water loss rate and enhanced drought tolerance compared to wild type. Transcriptome sequencing indicated significant changes in the expression levels of genes involved in ABA biosynthesis and its signaling pathways. Photosynthetic activity, kernel width and kernel weight was increased in ZmPIP1;1 overexpression maize, but not growth under normal condition compared with wild type. Moreover, interaction between ZmPIP1;1 and ZmPIP2;6 was observed by bimolecular fluorescence complementation (BiFC) experiment, resulting in re-localized on plasma membrane and chloroplast in maize mesophyll protoplast. Our study laid an important foundation for understanding the molecular mechanism of ZmPIP1;1, and provided a new method of molecular breeding for high photosynthetic efficiency.

TILLAGE & CULTIVATION·PHYSIOLOGY & BIOCHEMISTRY

Cropping effect and variety adaptability of winter-seeded spring wheat in Inner Mongolia Plain irrigation area

DONG Yu-Xin, WEI Bing-Qi, WU Qiang, ZHANG Yong-Ping

Acta Agronomica Sinica. 2021, 47(3):  481-493.  doi:10.3724/SP.J.1006.2021.01039

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Growing spring wheat in Inner Mongolia is challenging because of the short growing period, dry-hot winds, and heat-forced maturity. There are also problems with growing winter wheat varieties, such as frost damage, spring droughts, or “late spring cold”. These factors have restricted efforts to increase yields. In order to cope with these challenges, this study adopted a “winter-seeded spring wheat” planting model for growing wheat in Inner Mongolia and investigated wheat varieties with different vernalization requirements through two consecutive field trials. The effects of different varieties on seed germination and seedling emergence, growth, leaf physiological, root traits, and yield formation were analyzed. The results indicated that the spring varieties and some winter varieties of the tested wheat varieties were overwintered as seed and passed the vernalization stage, and matured normally in the following year. Under winter sowing conditions, the spring field germination rate of the tested wheat varieties was lower than that of spring sowing wheat, but the root system developed, and the adaptability to low temperature and drought was stronger. Three wheat varieties suitable for winter-sowing in the Inner Mongolia plain irrigation area were screened out by systematic clustering, including the spring variety Yongliang 4, winter cultivar Ningdong 11 and semi-winter cultivar Henong 7106. Their common characteristics were higher overwintering emergence rate, stronger stress resistance, relatively well-developed root system and higher yield performance, among which, Yongliang 4 could reach the same level as spring-seeded.

Effects of uniconazole and waterlogging stress in seedling stage on the physio logy and yield in adzuki bean

XIANG Hong-Tao, LI Wan, ZHENG Dian-Feng, WANG Shi-Ya, HE Ning, WANG Man-Li, YANG Chun-Jie

Acta Agronomica Sinica. 2021, 47(3):  494-506.  doi:10.3724/SP.J.1006.2021.04070

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In order to explore the difference on the resistance physiology and yield and the mitigation effect of uniconazole (S3307) pretreatment under waterlogging stress, the pot experiment was conducted using Longxiaodou 4 (LXD 4) and Tianjinhong (TJH). The anti-stress physiological indexes and yield were measured on 5th day after waterlogging stress and foliar spraying S3307 at seedling stage, and samples were taken every day. The results showed that leaf physiological indexes in waterlogging stress were changed during seedling stage, the content of H₂O₂, MDA, proline and soluble protein were significantly increased, as the same as the content of ABA, IAA, and SA, and the activities of SOD, POD, and CAT. Waterlogging treatment for five days resulted in a significant decrease in the output of LXD 4 in a single pot by 8.40% to 12.61%, and that of TJH decreased by 9.91% to 10.01%. S3307 had the effect of resisting waterlogging stress, and could effectively increase the content of proline and soluble protein in the leaf of adzuki bean, significantly reduced the content of H₂O₂ and MDA, significantly increased the activity of SOD and POD, the value of SOD/POD and SOD/CAT, significantly increased the ABA and SA content, and significantly inhibited the increase in IAA content. Foliar spraying S3307 significantly increased the output of LXD 4 by 2.85% to 6.18% under waterlogging treatment for four days, and significantly increased the yield of TJH by 2.85% to 3.95%, respectively. This study concluded that there were significant differences under physiological stress in reactive oxygen species accumulation, membrane lipid peroxidation, antioxidant enzyme activities and hormone levels among different varieties of adzuki bean under waterlogging stress. Spraying S3307 could effectively alleviate the effects of waterlogging stress on the physiology and yield in adzuki bean. The results provide a theoretical basis for further studying the physiological mechanism of adzuki bean resistance to waterlogging at the seedling stage and improving the yield of adzuki bean under waterlogging stress.

Response of grain filling and dehydration characteristics of kernels located in different ear positions in the different maturity maize hybrids to plant density

ZHU Ya-Li, WANG Chen-Guang, YANG Mei, ZHENG Xue-Hui, ZHAO Cheng-Feng, ZHANG Ren-He

Acta Agronomica Sinica. 2021, 47(3):  507-519.  doi:10.3724/SP.J.1006.2021.03024

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Exploring the regulation effect of planting density on grain filling and dehydration characteristics of kernels located in different ear positions in different maturity maize hybrids could provide theoretical and technical reference for high yield production for the mechanized grain harvest of spring maize in northern Shaanxi irrigation area. A field experiment was conducted using the medium maturity maize hybrid Xianyu 335 and the late maturity maize hybrid Dongdan 60 with four plant densities of 45,000 (D1), 60,000 (D2), 75,000 (D3), and 90,000 (D4) plants hm^-2 from 2018 to 2019. Their grain filling and dehydration characteristics at different grain positions and their correlation with climatic factors were analyzed. The results showed that increasing density could significantly increase the grain yield with different maturity maize hybrids with both hybrids reaching the highest yield under D4 treatment in 2018; Xianyu 335 and Dongdan 60 reached the highest yield under D4 and D3 treatments in 2019, respectively, and the 2-year average highest yields were 18,739 kg hm^-2 and 17,111 kg hm^-2, which were 32.2% and 27.7% higher than those under D1 treatment. With the increase of plant density the grain filling rate and the grain weight decreased, and the dehydration rate accelerated of different grain positions. Under D4 plant density, the average grain filling rate of the lower and upper grains of Xianyu 335 was 0.08 g d^-1 and 0.04 g d^-1 higher than that of Dongdan 60, and the grain weight was 3.6 g and 1.6 g higher than that of Dongdan 60, respectively. The correlation analysis showed that the grain moisture content of different grain positions was positively correlated with the effective accumulated temperature from silking to physiological maturity stage, but the total dehydration rate was not significantly correlated with grain filling rate. The grain dehydration rate of Xianyu 335 at different grain positions was high, and the average total dehydration rate of lower and upper grains was 0.006% °C d ^-1 and 0.005% °C d ^-1 higher than that of Dongdan 60. Furthermore, compared with the lower grains, the upper kernels had lower filling rate, longer filling period, smaller grain weight, faster dehydration at the later stage, and required less accumulated temperature to reach 28% and 25% moisture content. Based on our study, the upper kernels were more sensitive to higher plant density than lower kernels. Compared with Dongdan 60, the mid-mature maize hybrid Xianyu 335 has the higher grain filling rate, larger grain weight, and faster dehydration rate in the dense planting conditions. In conclusion, properly increased plant density coupled with middle-maturity maize hybrids is a potential way to increase the grain yield for mechanized grain harvest in the irrigation area of Northern Shaanxi.

Effects of drip irrigation and topdressing on dry matter weight, mineral nutrient absorption and yield of pod-bearing stage in peanut

QIN Wen-Jie, GUO Run-Ze, ZOU Xiao-Xia, ZHANG Xiao-Jun, YU Xiao-Na, WANG Yue-Fu, SI Tong

Acta Agronomica Sinica. 2021, 47(3):  520-529.  doi:10.3724/SP.J.1006.2021.04109

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This study was designed to clarify the effects of different fertilizer types and their mutual application on improving peanut yield, to determine the appropriate type of topdressing fertilizer and mutual application, and provide theoretical basis and technical guidance for scientific fertilization of peanut. Nitrogen (N), calcium (Ca), and boron (B) fertilizer were applied at the pod-pin stage under the condition of mulching drip irrigation in the field and the effects of different types of drip irrigation topdressing on dry matter weight, mineral nutrient absorption and yield of peanut in pod-bearing stage were analyzed. The results showed that the dry matter weight, nitrogen content and accumulation, calcium content and accumulation, and pod yield of peanut stems and leaves were significantly increased by topdressing of N, B, and Ca fertilizer in the pod-pin stage, however, the effect of topdressing of N, B, and Ca fertilizer alone was not as good as that of the combination of N, B, and Ca fertilizer, and the effect of topdressing of N, B, and Ca fertilizer on stem and leaf dry matter weight, nitrogen content and accumulation, calcium content and accumulation, and pod yield was better. Topdressing boron fertilizer could improve the boron content and its accumulation in peanut stems and leaves, while the combination of nitrogen and calcium fertilizer could promote the absorption and accumulation of boron in peanut. Peanut yield and stem (matter weight, nitrogen accumulation, calcium accumulation and leaf boron accumulation) were significantly positively related, stem (stem leaf nitrogen accumulation and leaf weight and the calcium accumulation) were significantly positive correlation, stem leaf nitrogen accumulation and stem leaf nitrogen content were significantly positive correlation, the calcium content in the stem leaf calcium accumulation and leaf were significantly positive correlation, stem leaf boron accumulation with stem and leaf boron content were significantly positive correlation. These results suggest that the application of N, B, and Ca promoted the absorption and accumulation of N, B, and Ca, increased the quality of dry matter, and consequently increased the yield of peanut.

Construction of critical nitrogen dilution curve based on dry matter in diffe rent organs of summer maize and estimation of grain yield

SU Wen-Nan, XIE Jun, HAN Juan, LIU Tie-Ning, HAN Qing-Fang

Acta Agronomica Sinica. 2021, 47(3):  530-545.  doi:10.3724/SP.J.1006.2021.03021

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It is essential to accurate and dynamic diagnosis of plant nitrogen status at vegetative growth stage for the assessment of plant nitrogen demand and the prediction of crop yield as well as the optimization of nitrogen management in maize. Plant-based nitrogen diagnostic tool can be used to optimize nitrogen management in summer maize production. The aim of this study was to develop and verify critical nitrogen concentration dilution curves based on dry matter in different tissue of the plant, and to establish the relationship between relative yield (RY) nitrogen nutrition index (NNI), and accumulated nitrogen deficit (AND) at different growth stages in maize. We conducted a 4-year field study using four nitrogen application rates (0, 150, 225, and 300 kg N hm^-2) and two maize cultivars (Zhengda 12 and Shaandan 609) to analyze the effects of nitrogen on dry matter at the vegetative growth stage, and based on leaf dry matter (LDM), stem dry matter (SDM), and plant dry matter (PDM), different critical nitrogen concentration dilution curves were developed. The results showed that the critical nitrogen concentration dilution curves based on LDM, SDM and PDM can well diagnose the nitrogen nutrition status of corn. The yield prediction results of three critical nitrogen concentration dilution curves showed that the relationship between RY and NNI, AND at different growth stages was highly significant, and the values of R ² were all greater than 0.65, where R ² was the largest at V12-VT, and the verification of the regression model showed reliable model performance during the V12-VT period, with R ² values greater than 0.92 and RMSE values less than 10%, which confirmed the stability of the relationship between V12 and VT. Generally, under certain conditions, the critical nitrogen concentration dilution curve based on LDM and SDM can be used to replace the critical nitrogen concentration dilution curve based on PDM. The stable relationship between RY and NNI, RY and AND in V12-VT stage can well explain the change of RY under restricted and unrestricted nitrogen and estimate the yield of summer maize. This study provides the basis for nitrogen management of pre-anthesis to improve maize grain yield.

RESEARCH NOTES

Dynamics in above-ground biomass accumulation after transplanting and its characteristic analysis in Yongyou japonica/indica hybrids

WEI Huan-He, ZHANG Xu-Bin, GE Jia-Lin, MENG Tian-Yao, LU Yu, LI Xin-Yue, TAO Yuan, DING En-Hao, CHEN Ying-Long, DAI Qi-Gen

Acta Agronomica Sinica. 2021, 47(3):  546-555.  doi:10.3724/SP.J.1006.2021.02033

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In this study, two japonica/indica hybrids (JIH) (Yongyou 1540 and Yongyou 4540 with the total growth duration ranged from 169 to 171 days) of Yongyou series, two japonica conventional (JC) varieties (Zhendao 13 and Wuyunjing 30 with the total growth duration ranged from 159 to 160 days), and two indica hybrids (IH) varieties (Liangyoupeijiu and Yangliangyou 6 with the total growth duration ranged from 140 to 141 days) were grown to compare the characteristics and differences of above-ground biomass accumulation after transplanting among three variety types in 2015 and 2016. Grain yield of JIH was averaged 12.4 t hm ^-2 for two years, and 7.8% and 23.3% higher at P < 0.05 than that of JC and IH, respectively. Compared with JI and IH, JIH had lower panicle per m ², filled-grain percentage, and 1000-grain weight, while more spikelets per panicle. JIH also had higher total biomass weight at maturity stage, while lower harvest index. The biomass weight in stem and leaf and their ratio at maturity stage were the highest in JIH and lowest in IH. JIH had the highest panicle weight while IH had the lowest panicle weight, and the opposite trend was observed in the ratio of panicle weight to the total biomass weight at maturity among three variety types. The above-ground biomass accumulation dynamics after transplanting of JIH, JC, and IH were all well fitted by Gompertz equation. The above-ground biomass accumulation rate of different variety types showed a single-peak curve of increasing trend and then a decreasing trend after transplanting. The maximum biomass accumulation rate of JIH, JC, and IH was observed at 61-62, 64-66, and 63-64 days after transplanting, respectively. The maximum biomass accumulation rate of JIH was 17.7% and 17.3% higher than that of JC and IH, respectively. Compared with JC and IH, JIH had higher mean biomass accumulation rate in the early, middle, and late stages; and JIH had lower duration days in the early and middle stages and higher duration days in the late stages. Compared with JC and IH, JIH had higher biomass accumulation in the early, middle, and late stages. In this study, a Gompertz model was established that conformed to the dynamic characteristics of above-ground biomass accumulation after transplanting in different variety types. Compared with JC and IH, JIH had superior biomass accumulation in the early, middle, and late stages; the higher biomass accumulation in the early and middle stages were due to the higher biomass accumulation rate, and higher biomass accumulation in the late stage was due to its higher biomass accumulation period and accumulation rate.

Identification and screening of saline-alkali tolerant peanut cultivars during whole growth stage

YAN Cai-Xia, WANG Juan, ZHAO Xiao-Bo, SONG Xiu-Xia, JIANG Chang-Song, SUN Quan-Xi, YUAN Cui-Ling, ZHANG Hao, SHAN Shi-Hua

Acta Agronomica Sinica. 2021, 47(3):  556-565.  doi:10.3724/SP.J.1006.2021.04107

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In order to improve the planting structure of coastal saline-alkali land and enlarge the growing area of peanut in the Yellow River Delta. A total of 22 peanut elite cultivars were tested in saline-alkali area of Dongying in 2016 and 2017. Nine trait indices were separately investigated for five randomly selected individuals during whole growth stage. Variance analysis, correlation analysis and clustering analysis were used to evaluate the saline-alkali tolerance of the materials and to screen saline-alkali tolerant indices. Variance analysis showed that the seedling rates of all cultivars had an obvious decrease compared with those of the control. The growth, development and yield formation were essentially inhibited by saline-alkali stress. There were great differences among tested materials based on nine identification indices. Correlation analysis indicated that RYP and RPY had a significantly positive correlation with RSDW, RMSH and RBL. Additionally, RPY was also obviously related to RSR, RRDW, and RYP. Based on the results of clustering analysis, tested materials were divided into four saline-alkali tolerance grades, in which seven belonged to high tolerant grade I, 11 to tolerant grade II, 3 to susceptible grade III and 1 to highly susceptible grade IV. Huayu 9307, Huayu 9312, Huayu 9313, 6P03, Huayu 9305 and Huayu 6303 could be widely grown in the coastal saline-alkali area as high yield cultivars. In conclusion, the results suggested that RSDW, RMSH, RSR, RYP, RBL, and RRDW could be taken as simple and intuitive indices in the identification of saline-alkali tolerant peanut genotypes.

Grain filling characteristics of summer maize varieties under different sowing dates in the Huang-Huai-Hai region

XU Tian-Jun, LYU Tian-Fang, ZHAO Jiu-Ran, WANG Rong-Huan, ZHANG Yong, CAI Wan-Tao, LIU Yue-E, LIU Xiu-Zhi, CHEN Chuan-Yong, XING Jin-Feng, WANG Yuan-Dong, LIU Chun-Ge

Acta Agronomica Sinica. 2021, 47(3):  566-574.  doi:10.3724/SP.J.1006.2021.03023

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In order to provide helpful information for maize variety selection and realizing high yield, the grain filling characteristics of 18 summer maize varieties were investigated under 6/10 (S1), 6/20 (S2), and 6/30 (S3). The results showed that: (1) There were significant differences in the final 100-grain dry weight among varieties and sowing date treatments, characterized by S1 (35.20 g) > S2 (33.45 g) > S3 (31.38 g), and the range of variation was 28.50 g (HM 1) to 36.37 g (JNK 728). (2) The average filling rate (Gave) under different sowing date treatments was S1 (0.74 g 100-grain ^-1d^-1) > S2 (0.65 g 100-grain ^-1d^-1) > S3 (0.57 g 100-grain ^-1d^-1). The average grain filling rate of S1 was 0.09 g 100-grain^-1d^-1and 0.17 g 100-grain^-1d^-1 higher than that of S2 and S3, increased by 13.85% and 29.82%, respectively. The G_ave of JNK 728 (0.75 g 100-grain ^-1 d^-1) was the highest among varieties, which significantly higher than ZD 958 and XY 335 (0.58 g 100-grain^-1 d^-1 and 0.67 g 100-grain^-1 d^-1), increased by 29.31% and 11.94%. The active grain filling period (P) showed that S1 (47.85 d) < S2 (51.39 d) < S3 (55.04 d). (3) The yield under different sowing date treatments was S1 (10,628.67 kg hm^-2) > S2 (10,207.65 kg hm ^-2) > S3 (9144.59 kg hm ^-2), with S1 4.12% and 16.23% higher than S2 and S3, respectively. Among them, NK 815, MC 121, JNK 729, MC 812, JNK 728 and XY 335 had relatively high yields, with an average of 10,730.56 kg hm^-2, significantly higher than ZD 958 (10,080.85 kg hm^-2), increased by 6.44%. (4) Correlation analysis showed that yield level was significantly and positively correlated with G_ave (0.70 ^**) and grain weight (0.68^**), and was significantly and negatively correlated with P (-0.36 ^**); Grain weight was significantly correlated with Gave (0.58 ^**). In conclusion, maize yield, grain weight and grain filling rate reduced with the sowing date delay, but P increased accordingly, early sowing properly was beneficial to achieve higher yield in Huang-Huai-Hai summer maize region, by selecting varieties such as JNK 728, JNK 729, MC 812, MC 121, NK 815, and XY 335 which characterized by suitable growing period, higher grain filling rate, suitable active grain filling period and higher yield level. JNK 728, characterized by medium-early maturity, higher grain filling rate and yield, was suitable for the later sowing conditions or areas with insufficient accumulated temperature, and could reach physiological maturity in mid-October when sowing at the end of June.