Table of Content

12 January 2025, Volume 51 Issue 1

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REVIEW

Research progress in phytohormone regulation of square and boll shedding in cotton

XIE Zhang-Shu, XIE Xue-Fang, TU Xiao-Ju, LIU Ai-Yu, DONG He-Zhong, ZHOU Zhong-Hua

Acta Agronomica Sinica. 2025, 51(1):  1-29.  doi:10.3724/SP.J.1006.2025.44122

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Cotton square and boll shedding is a common phenomenon, which can occur as an active adaptive response to adverse environmental stress or as a passive loss due to genetic characteristics, environmental conditions, cultivation practices, and various biotic and abiotic stresses. Square and boll shedding directly impacts cotton yield. However, most existing studies, both domestic and international, primarily focus on preliminary findings from the 1950s and 1960s concerning the influence of ethylene and abscisic acid on cotton shedding. Based on insights from other plant species, it appears that square and boll shedding is closely related to a decline in growth-promoting hormones—such as auxin, gibberellin, and cytokinin—and an increase in growth-inhibiting hormones like ethylene and abscisic acid. These hormones not only regulate metabolic processes within the plant but also coordinate signaling pathways that play a pivotal role in the shedding process. In this paper, we review the molecular regulatory mechanisms underlying the formation and functioning of abscission zones, as well as the hormonal responses and regulatory mechanisms involved in the shedding of cotton squares and bolls, and in the shedding of other plant (reproductive) organs in recent years. Our findings reveal a lack of comprehensive research on cotton square and boll shedding, with most studies focusing on the limited effects of a few hormones on cotton reproductive growth, while failing to investigate the deeper mechanisms that lead to shedding. Therefore, future research should prioritize exploring the genetic basis of cotton square and boll shedding, identifying new gene resources for breeding varieties resistant to shedding, and enhancing our understanding of the relationship between shedding and hormone regulation in cotton as a model plant. This will provide a theoretical foundation and technical support for improving cotton yield.

CROP GENETICS & BREEDING·GERMPLASM RESOURCES·MOLECULAR GENETICS

Comprehensive evaluation of regional trial varieties of medium mature hybrid cotton in the Yellow River Basin based on GYT biplot

LI Chao, FU Xiao-Qiong

Acta Agronomica Sinica. 2025, 51(1):  30-43.  doi:10.3724/SP.J.1006.2025.44093

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The analysis and evaluation of the regional cotton trials for medium-maturing hybrid varieties in the Yellow River Basin provide a scientific basis for optimizing varietal distribution and improving trait characteristics. This study comprehensively evaluated the yield, quality, agronomic traits, and disease resistance of 30 tested varieties in the Yellow River Basin from 2022 to 2023 using the GYT biplot method. An in-depth analysis was conducted on key traits, including lint yield, boll weight, number of bolls per plant, pre-frost yield rate, lint percentage, first fruiting branch node, number of fruiting branches, growth period, plant height, seed index, fiber length, fiber strength, micronaire, fiber elongation, fiber uniformity, Fusarium wilt index, and Verticillium wilt index. The joint analysis of variance showed that genotype and environmental effects were highly significant, and most genotype × environment interaction effects were significant or highly significant over the two-year experiment. Notably, the sum of squares for interaction effects exceeded that for genotype effects. Among the tested varieties, ZMS 9B07 demonstrated wider adaptability and higher lint yield compared to the control variety ZMS 9711. Compared to the GT biplot, the GYT biplot method exhibited a higher proportion of explained variation, better model fit, and greater reliability. This method more intuitively displays the characteristics of the tested varieties, providing a valuable reference for the comprehensive evaluation of multiple crop traits in China.

Phylogenetic and functional analysis of the BnaSLY1 genes in Brassica napus L.

LI Jia-Xin, HUANG Ying-Ying, WU Lu-Mei, ZHAO Lun, YI Bin, MA Chao-Zhi, TU Jin-Xing, SHEN Jin-Xiong, FU Ting-Dong, WEN Jing

Acta Agronomica Sinica. 2025, 51(1):  44-57.  doi:10.3724/SP.J.1006.2025.44079

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Gibberellins regulate plant epidermal cell growth, stem and leaf expansion, and plant architecture. In Arabidopsis, SLY1 encodes an F-box protein that modulates plant growth by targeting the negative regulator of GA signaling, the DELLA protein, for ubiquitination and subsequent degradation. However, the function of BnaSLY1 in Brassica napus has not been previously revealed. In this study, we characterized the expression patterns and performed a phylogenetic analysis of BnaSLY1. Using CRISPR/Cas9 technology, we generated mutants with different copy numbers of BnaSLY1. By integrating RNA-Seq analysis, we investigated the biological functions of BnaSLY1 and its impact on the growth and development of Brassica napus. Our results showed that there are two copies of SLY1 in Brassica napus, with similar expression patterns and constitutive expression. The protein is localized in the nucleus and is highly conserved among different varieties of rapeseed and cruciferous plants. Phenotypic analysis of mutants revealed that, compared to the control, single mutants bnaa01sly1 and bnaa06sly1 exhibited delayed flowering and significantly reduced plant height, while the double mutant bnasly1 showed a dark green leaf phenotype, increased leaf thickness, further delayed flowering, and further reduced plant height. RNA-Seq analysis between Westar and bnasly1 showed significant enrichment of differentially expressed genes in the auxin signaling pathway and wax biosynthesis pathway, with several flowering time-related genes showing significant expression changes. This study demonstrates that BnaSLY1 not only influences plant height and flowering time but also affects epidermal wax synthesis, thereby laying a theoretical foundation for exploring the crucial role of the GA signaling pathway in the growth and development of Brasscia napus.

Preliminary investigation of the SiLTP1: a lipid transfer protein gene involved in the salt tolerance of foxtail millet

MENG Fan-Hua, LIU Min, SHEN Ao, LIU Wei

Acta Agronomica Sinica. 2025, 51(1):  58-67.  doi:10.3724/SP.J.1006.2025.44092

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Soil salinization poses a significant barrier to agricultural productivity. Enhancing the salt tolerance of crops is crucial for the effective utilization of saline-alkali land, thereby ensuring food security and improving agricultural efficiency. Lipid transfer proteins (LTPs) are a class of small, widely distributed proteins in higher plants, playing crucial roles in plant growth, signal transduction, and responses to various biotic and abiotic stresses. In a previous study, a lipid transfer protein gene, designated SiLTP1, was cloned from foxtail millet. In this study, we constructed both a prokaryotic expression vector and a plant binary overexpression vector for SiLTP1. The prokaryotically expressed protein and four homozygous transgenic lines were successfully obtained and characterized. In vitro salt tolerance assays revealed that the SiLTP1 protein exhibited a notable degree of salt tolerance. Physiological measurements of the transgenic seedlings indicated reduced oxidative damage, as evidenced by lower malondialdehyde (MDA) accumulation, increased superoxide dismutase (SOD) activity, and reduced hydrogen peroxide (H₂O₂) levels under salt stress, demonstrating enhanced salt tolerance. These findings suggest that SiLTP1 plays a positive role in regulating salt tolerance in foxtail millet, potentially by mitigating oxidative stress. This study provides a theoretical foundation and valuable genetic resources for the future development and breeding of salt-tolerant foxtail millet varieties.

Allelic variation and distribution of peroxidase activity genes TaPod-A1, TaPod-A3, and TaPod-D1 of wheat in Xinjiang, China

LIU Xin-Yuan, CHENG Yu-Kun, WANG Li-Li, ZHAN Shuai-Shuai, MA Meng-Yao, GUO Ling, GENG Hong-Wei

Acta Agronomica Sinica. 2025, 51(1):  68-78.  doi:10.3724/SP.J.1006.2025.41034

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To further improve the quality of wheat flour, functional markers for the TaPod-A1, TaPod-A3, and TaPod-D1 loci were employed to detect allelic variations in 110 wheat varieties (lines) from Xinjiang. Genotypic and phenotypic ANOVA results revealed that the TaPod-A1b (35.5%), TaPod-A3c (53.6%), and TaPod-D1b (60%) alleles associated with significantly higher POD activity compared to TaPod-A1a (64.5%), TaPod-A3a (46.4%), and TaPod-D1a (40%) alleles, respectively. In Xinjiang wheat cultivars, the distribution frequencies of favorable high-POD activity alleles at the TaPod-A1, TaPod-A3, and TaPod-D1 loci were higher in introduced varieties (lines)≈self-fertile varieties (lines) compared to landraces. Notably, the TaPod-A3b allele was absent in all 110 Xinjiang wheat samples, suggesting that it is a rare allele. The average POD activity of cultivars (lines) with specific alleles at the TaPod-A1, TaPod-A3, and TaPod-D1 genes followed the order: TaPod-A1b/TaPod-A3c/TaPod-D1b (2836.25 U g^-1 min^-1) > TaPod-A1b/TaPod-A3c/TaPod-D1a (2796.00 U g^-1 min^-1) > TaPod-A1b/TaPod-A3a/TaPod-D1b (2520.31 U g^-1 min^-1) > TaPod-A1a/TaPod-A3c/TaPod-D1b (2473.91 U g^-1 min^-1) > TaPod-A1a/TaPod-A3a/TaPod-D1b (2407.65 U g^-1 min^-1) > TaPod-A1b/TaPod-A3a/TaPod-D1a (2339.06 U g^-1 min^-1) > TaPod-A1a/TaPod-A3c/TaPod-D1a (2320.38 U g^-1 min^-1) > TaPod-A1a/TaPod-A3a/TaPod-D1a (2210.69 U g^-1 min^-1). Among these, the allele combination TaPod-A1b/TaPod-A3c/TaPod-D1b exhibited significantly higher POD activity (2836.25 U g^-1 min^-1) compared to the combination TaPod-A1a/TaPod-A3a/TaPod- D1a (2210.69 U g^-1 min^-1) (P < 0.01), indicating that varieties with superior allele combinations exhibit enhanced POD activity.

Genetic relationship analysis and fingerprints construction of faba bean varieties in Qinghai province based on SSR markers

ZHENG Dong, ZHOU Xian-Li, TENG Chang-Cai, HOU Wan-Wei, ZHANG Hong-Yan, LIU Yu-Jiao

Acta Agronomica Sinica. 2025, 51(1):  79-90.  doi:10.3724/SP.J.1006.2025.44066

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To clarify the population structure and relationships among cultivated varieties, advanced lines, and backbone parents of faba bean in Qinghai province, forty-six pairs of SSR primers with high polymorphism, stability, and repeatability were used to analyze the genetic diversity of thirty-six varieties (lines) and construct genetic fingerprints. The results revealed that 262 alleles were detected using the forty-six primer pairs through capillary electrophoresis. The number of polymorphic alleles (Na) per primer ranged from two to fifteen, with an average of 5.696 alleles. The average number of effective alleles per locus was 2.988, ranging from 1.180 to 9.257. The Shannon index ranged from 0.287 to 2.444, with an average of 1.210. The polymorphism information content (PIC) varied from 0.141 to 0.883, with an average of 0.553, indicating rich genetic diversity among the faba bean varieties in Qinghai. Clustering analysis grouped the 36 materials into four subgroups: subgroup I (twenty-four materials), subgroup II (four materials), subgroup III (seven materials), and subgroup IV (one material). Population genetic structure and principal coordinate analyses divided the materials into two subgroups, with subgroup I containing seventeen materials and subgroup II containing nineteen materials. There was some overlap between the subgroups identified by clustering and those identified by population structure analysis, which clarified the genetic relationships and population structure of the main faba bean cultivars in Qinghai province. On this basis, four core primer pairs were selected to construct genetic fingerprints for the thirty-six materials, which were subsequently stored in a two-dimensional code. The fingerprinting of the main faba bean cultivars in Qinghai provides an effective tool for variety identification and offers technical support for parental selection and the protection of new varieties in future faba bean breeding programs in the region.

Identification and genome-wide association study of specialized seedling grass barley cultivars

MA Min-Hu, CHANG Hua-Yu, CHEN Zhao-Yan, REN Zeng, LIU Ting-Hui, XING Guo-Fang, GUO Gang-Gang

Acta Agronomica Sinica. 2025, 51(1):  91-102.  doi:10.3724/SP.J.1006.2025.41028

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Seedling grass factories represent an innovative strategy to ensure a consistent year-round forage supply for herbivores. This study was conducted to assess the conversion efficiency of seedling grass and to identify loci governing biomass in a diverse collection of 124 Chinese barley breeding varieties and germplasm. Our results indicate that following barley seed germination, the biomass of seedling grass in hydroponic systems undergoes exponential growth, leveling off after seven days. Within the plant factory setting, we have pinpointed ten varieties with superior conversion rate for seedling grass, including Dongqing 16 and Zaqing 6. A negative correlation was detected between the biomass of seedling grass and the thousand-kernel weight of the seeds. Genome-wide association studies revealed twelve QTL loci linked to seedling grass biomass, and eight candidate genes implicated in biomass regulation were predicted. This research not only identifies high-conversion varieties suitable for production in barley seedling grass factories but also lays the groundwork for genetically enhancing barley varieties specifically for seedling grass production.

Development of SSR markers and database based on genomes of sugarcane and its relatives

KUANG Bo-Wen, WEI Ni, LIU Jin-Dian, CHEN Mei-Yan, MAO Xing-Jie, DUAN Wei-Xing, YANG Xi-Ping

Acta Agronomica Sinica. 2025, 51(1):  103-116.  doi:10.3724/SP.J.1006.2025.44056

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Sugarcane (Saccharum spp. hybrid) is an important crop for both sugar production and bioenergy. However, due to the complexity of the sugarcane genome, research in its population genetics has lagged behind other crops. Currently, the reference genome for sugarcane still requires significant improvements. The development of SSR (Simple Sequence Repeat) markers and databases based on the genomes of sugarcane and its relatives will be instrumental in advancing population genetics research. In this study, we identified SSRs from the genomes of three sugarcane species (Saccharum spontaneum, Saccharum officinarum, and Saccharum spp. hybrid) and two related species (Miscanthus sinensis and Sorghum bicolor). We quantified and categorized the SSRs for each genome, selecting those with high polymorphism for the genetic diversity analysis of 104 sugarcane-related materials. A total of 1,860,645 SSRs were identified across the five genomes, with mononucleotide, dinucleotide, and trinucleotide repeats being the most common. Synteny analysis of SSRs across the genomes revealed the evolutionary relationships among species, with the kinship order from closest to most distant being: R570, Saccharum officinarum, Saccharum spontaneum, Miscanthus sinensis, and Sorghum bicolor. Genetic diversity analysis using SSR and InDel markers showed that Banmao 92-105 was the first to diverge from other samples, with Saccharum spontaneum forming a distinct group, Saccharum robustum and Saccharum officinarum clustering together, and Saccharum spp. hybrid forming its own separate group. Additionally, we developed a web-based database for sugarcane SSRs, which includes the identified SSRs from the five genomes, along with corresponding primers and other related information. This study provides a valuable molecular tool for sugarcane research and breeding efforts.

Identification of the R2R3-MYB transcription factor family and screening of genes regulating flavonoid synthesis in mung bean

GUO Fei-Xiang, LI Chun-Xia, ZHOU Shuang, GUO Bin-Bin, ZHANG Jun, MA Chao

Acta Agronomica Sinica. 2025, 51(1):  117-133.  doi:10.3724/SP.J.1006.2025.44077

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The R2R3-MYB transcription factor family plays a crucial regulatory role in the synthesis of secondary metabolites, stress responses, and the growth and development of plants. This study employed bioinformatics analysis to identify the R2R3-MYB transcription factors across the entire genome of mung bean (Vigna radiata L.), and to predict their physicochemical properties, phylogenetic evolution, chromosome localization, cis-acting elements of the promoter, and gene structure. The expression patterns of mung bean under different tissues, exogenous hormones, and stress conditions were analyzed using transcriptome data and Quantitative Real-time PCR (RT-PCR). R2R3-MYB members potentially involved in regulating the biosynthesis of mung bean flavonoids were screened through correlation analysis and protein interaction networks. The results demonstrated that a total of 168 R2R3-MYB members were identified in mung bean, 145 of which were distributed across 11 chromosomes, while the chromosome information for 23 members remains unknown. Most of these members contain three exons encoding proteins ranging from 99 to 1645 amino acids and are all hydrophilic. The phylogenetic analysis divided the R2R3-MYB gene family in mung beans into 30 subgroups (V1-V30), revealing structural differences among members of different subgroups. Collinearity analysis within the mung bean genome indicated that all segmental duplication events underwent purifying selection. Analysis of cis-acting elements in the promoter regions of the R2R3-MYB genes in mung beans revealed a large number of hormone-responsive and stress-responsive elements, as well as a small number of flavonoid synthesis-responsive elements. Gene expression analysis showed that members with higher expression levels in leaves, petioles, hypocotyls, and seed coats accounted for 15.5%, 16.1%, 16.1%, and 10.7% of the total, respectively. RT-PCR analysis indicated that the relative expression levels of almost all R2R3-MYB family members significantly decreased under low-temperature stress, with different members had diverse response patterns to stress. Protein interaction and correlation analysis suggested that the genes VrMYB6, VrMYB77, and VrMYB93 may be involved in the regulation of flavonoid biosynthesis in mung beans. The results of this study lay the foundation for further in-depth research on the function of the R2R3-MYB transcription factor family in mung beans.

Analysis of expression patterns of laccase gene family members in Brassica napus and their association with stem fracture resistance

XU Lin-Shan, GAO Geng-Dong, WANG Yu, WANG Jia-Xing, YANG Ji-Zhao, WU Ya-Rui, ZHANG Xiao-Han, CHANG Ying, LI Zhen, XIE Xiong-Ze, GONG De-Ping, WANG Jing, GE Xian-Hong

Acta Agronomica Sinica. 2025, 51(1):  134-148.  doi:10.3724/SP.J.1006.2025.44035

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Laccase is a family of copper-containing polyphenol oxidases primarily involved in lignin synthesis and resistance to various stresses in plants. In this study, members of the laccase gene family (BnaLACs) in Brassica napus were identified, and their physical and chemical properties were measured, including the number of amino acids, molecular weight, isoelectric point, instability index, and aliphatic index. The chromosome positions, evolutionary relationships, gene structures, and tissue expression patterns of these genes were subsequently predicted and analyzed. The results showed that the Brassica napus genome contains 53 BnaLAC family members, which are generally alkaline and stable proteins. Most BnaLACs are located in the vacuole membrane and outside the cell. Gene structure analysis revealed that BnaLACs have conserved structures. Tissue expression pattern analysis indicated that BnaLACs are expressed in all tissues except anthers, with higher expression levels in roots, seeds, silique walls, and stems. The expression pattern of BnaLAC4s in stems was specifically analyzed, and it was found that BnaA05G0074200ZS is significantly correlated with lodging resistance in Brassica napus. Haplotype analysis showed significant differences in lodging resistance and lignin content between different BnaA05G0074200ZS haplotype lines. The results of this study provide a foundation for further analysis of the functions of the laccase gene family in Brassica napus and the mechanisms underlying stem lodging resistance.

TILLAGE & CULTIVATION·PHYSIOLOGY & BIOCHEMISTRY

Effects of manure replacement of chemical fertilizer nitrogen on yield, nitrogen accumulation, and quality of foxtail millet

WANG Yuan, XU Jia-Yin, DONG Er-Wei, WANG Jin-Song, LIU Qiu-Xia, HUANG Xiao-Lei, JIAO Xiao-Yan

Acta Agronomica Sinica. 2025, 51(1):  149-160.  doi:10.3724/SP.J.1006.2025.44085

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The partial substitution of chemical fertilizer with manure is increasingly recognized as a promising strategy for achieving sustainable agriculture. This study aimed to investigate the effects of different manure substitution ratios on grain yield and its components, plant nitrogen accumulation, grain appearance quality, carotenoid content, and pasting properties. A two-year field experiment (2020-2021) was conducted with six treatments: no fertilizer application (CK), chemical fertilizer (NPK), 25% substitution of chemical nitrogen with manure (25% M), 50% substitution (50% M), 75% substitution (75% M), and 100% substitution (100% M). Results indicated that plant nitrogen accumulation was highest with 25% M and decreased as the proportion of manure substitution increased, which subsequently affected grain yield and quality. In 2020, 25% M increased plant nitrogen accumulation by 9.6% compared to NPK. In 2021, 25% M produced the highest values for plant nitrogen accumulation, aboveground biomass, grain yield, and grain number per ear, with increases of 6.1%, 12.0%, 15.4%, and 12.0%, respectively, compared to NPK. Grain appearance quality, pasting properties, and carotenoid content were significantly influenced by the 50% M treatment. Compared to NPK, 50% M increased the a* parameter (indicating red or green coloration) by 6%, CCI (indicating orange coloration) by 6%, and final viscosity by 7.8%. Additionally, amylopectin, total starch, lutein, zeaxanthin, and yellow pigment contents increased by 7.4%, 4.3%, 20.68%, 17.4%, and 2.8%, respectively, under 50% M compared to NPK. However, 100% M significantly reduced plant nitrogen accumulation, biomass, grain number per ear, and grain yield relative to NPK, and had no positive effects on lutein and zeaxanthin contents. Pearson correlation analyses revealed that plant nitrogen accumulation was negatively related to grain weight, amylose content, and setback viscosity in 2020 and 2021. A negative correlation was also observed between plant nitrogen accumulation and total starch content, protein content, peak viscosity, and yellow pigment content in 2021, while a positive correlation was found between plant nitrogen accumulation and trough viscosity. In conclusion, under a total nitrogen application rate of 120 kg hm^-2, substituting 25%-50% of chemical nitrogen with manure enhanced plant nitrogen accumulation, which in turn improved yield, grain appearance quality, pasting properties, and carotenoid content in foxtail millet grains.

Effects of planting density on photosynthetic production and yield formation of soybean varieties from different eras

DING Shu-Qi, CHENG Tong, WANG Bi-Kun, YU De-Bin, RAO De-Min, MENG Fan-Gang, ZHAO Yin-Kai, WANG Xiao-Hui, ZHANG Wei

Acta Agronomica Sinica. 2025, 51(1):  161-173.  doi:10.3724/SP.J.1006.2025.44065

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Planting density is an effective way to harness the production potential of elite soybean varieties, yet the response differences to planting density among soybean varieties over a breeding time span of up to 100 years remain unclear. To clarify the effects of planting density on the photosynthetic production and yield formation of soybean varieties released in different eras, this study used 50 soybean varieties released from the 1930s to the 2020s. The response differences in leaf area index (LAI), leaf area index growth rate (LGR), leaf area duration (LAD), dry matter accumulation, crop growth rate (CGR), lower leaf senescence, and yield were explored under different planting densities (normal density of 200,000 plants hm^-2 and high density of 300,000 plants hm^-2) for soybean varieties from different eras (1930s-1940s, 1950s-1960s, 1970s-1980s, 1990s-2000s, and 2010s-2020s). The results showed that with the advancement of breeding eras, both the photosynthetic production capacity and yield of soybeans gradually increased. Compared with old varieties (1930s-1940s, 1950s-1960s, and 1970s-1980s), new varieties (1990s-2000s and 2010s-2020s) showed better growth status at high density. The increase in LAI of new varieties at high density was more substantial, with increases of 17.79% and 23.06% at the R4 stage, and the decrease in LAI from the R4 to R6 stage was slower, resulting in a more significant increase in LAD. At the R6 stage, the dry matter accumulation of new varieties at high density increased by 25.28% and 28.96%, respectively, and their CGR also significantly increased (P < 0.05) by 21.66% and 25.38%, respectively. Moreover, the new varieties showed strong senescence resistance at high density, with smaller decreases in the amount of upward displacement of yellow leaf nodes and leaf SPAD values of the lower leaves. In terms of yield, new varieties experienced greater increases in the number of seeds and pods per unit area at high density, with a smaller decrease in 100-seed weight, resulting in a significant (P < 0.05) yield increases of 4.49% and 5.04%, respectively. In conclusion, at the beginning of the growth period, new varieties showed a strong ability to increase the ‘source’ under high density, with high and stable leaf source values, greater light energy interception, and substantial dry matter accumulation, promoting the rapid development of the seed ‘sink’. During the later growth period, the slower decrease in LAI, robust photosynthetic capacity of the population and thorough seed filling significantly increased the number of seeds and pods per unit area, thereby compensating for the slight decrease in 100-seed weight and achieving a significant increase in soybean yield.

Effects of alternate wetting and drying irrigation and plant growth regulators on photosynthetic characteristics and endogenous hormones of rice

ZHAO Li-Ming, DUAN Shao-Biao, XIANG Hong-Tao, ZHENG Dian-Feng, FENG Nai-Jie, SHEN Xue-Feng

Acta Agronomica Sinica. 2025, 51(1):  174-188.  doi:10.3724/SP.J.1006.2025.32055

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The purpose of this study was to investigate the effects of alternate wetting and drying irrigation and plant growth regulators (PGRs) on photosynthetic characteristics, endogenous hormones, and yield of rice. Pot and field experiments were conducted using Longjing 31 as the experimental material. Two irrigation treatments were set up: moderate alternative wetting and drying irrigation (MI) and heavy alternating wetting and drying irrigation (HI). The effects of these irrigation treatments on yield formation and photosynthetic characteristics of rice were examined. Additionally, three PGRs—diethyl aminoethyl hexanoate (DA), 6-benzylaminoadenine (BA), and BA + DA—were sprayed at the full tillering stage and sword leaf expansion stage to analyze their effects on photosynthetic characteristics and endogenous hormones of rice post-heading. Differences in dry matter accumulation, photosynthetic characteristics, endogenous hormones, and yield under alternate wetting and drying irrigation, PGRs, and their interactions were studied. The results showed that MI significantly increased leaf area, leaf area index, SPAD value, and net photosynthetic rate. It also increased the contents of IAA, GA₃, and ZR in flag leaves and grains, decreased ABA content, and enhanced dry matter accumulation and stem-sheath matter transport capacity. Consequently, MI improved internode characteristics, seed setting rate, grain number, and weight per panicle, resulting in an actual yield increase of 5.30% (Pot) and 5.11% (Field) compared to HI. In terms of plant growth regulators, BA+DA significantly increased the net photosynthetic rate, stomatal conductance, and intercellular carbon dioxide concentration of flag leaves post-heading. It also increased dry matter accumulation, stem-sheath matter transport capacity, and the contents of IAA, GA₃, and ZR in flag leaves and grains. This led to increases in 1000-grain weight, seed setting rate, harvest index, grain number per panicle, and grain weight per panicle, boosting yield by 6.60% (Pot) and 6.05% (Field), followed by BA, compared to CK. The interaction of alternate wetting and drying irrigation and PGRs had significant effects on leaf area index, endogenous hormone content, grains per panicle, and 1000-grain weight. Notably, the MI×(BA+DA) treatment was more effective in maintaining the functional duration of green leaves post-heading, increasing leaf SPAD value, leaf area, leaf area index, and net photosynthetic rate. It also enhanced dry matter accumulation, stem-sheath matter transport, and the contents of IAA, GA₃, and ZR in leaves and grains, promoting the export of assimilates to grains. This treatment, on the basis of stable panicle number, improved 1000-grain weight, grain number and grain weight per panicle, seed setting rate, and harvest index. Compared to other treatments and CK, it achieved a yield increase of 3.17%-12.57% (Pot) and 3.14%-11.55% (Field). However, HI×(BA+DA) could achieve the yield effect of MI×CK. These results indicate that alternate wetting and drying irrigation combined with spraying BA+DA can be used as a water-saving chemical control cultivation measure for high-yield and high-efficiency rice production in this region.

Estimation of canopy nitrogen concentration in maize based on UAV multi- spectral data and spatial nitrogen heterogeneity

HAO Qi, CHEN Tian-Lu, WANG Fu-Gui, WANG Zhen, BAI Lan-Fang, WANG Yong-Qiang, WANG Zhi-Gang

Acta Agronomica Sinica. 2025, 51(1):  189-206.  doi:10.3724/SP.J.1006.2025.43015

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Remote sensing diagnosis of crop canopy nitrogen nutrition is crucial for guiding precise nitrogen application and improving crop nitrogen efficiency and yield. To address the issue of maize canopy depth significantly affecting the accuracy of UAV-based nitrogen concentration estimation, this study analyzed the spatial heterogeneity characteristics of maize canopy nitrogen concentration. This analysis was based on multi-spectral data and measured nitrogen concentration data from UAV across fields with different nitrogen fertilizer treatments in 2022 and 2023. Using the random forest algorithm, we identified the effective leaf layer for estimating canopy nitrogen concentration. We further constructed an estimation model for effective leaf nitrogen concentration by combining the random forest algorithm with multi-spectral vegetation indices, and then converted the effective leaf nitrogen concentration to the canopy scale to estimate the overall canopy nitrogen concentration. The results were as follows: (1) The nitrogen concentration of the maize canopy at the 9-leaf extension and large trumpet stages was highest in the upper leaves, followed by the middle and lower leaves. At the silk-spinning and milk-ripening stages, the nitrogen concentration was highest in the middle leaves, followed by the upper and lower leaves. (2) The effective leaf layers for estimating canopy nitrogen concentration at each growth stage were the lower layer, middle layer, middle layer, and middle layer, respectively. The random forest regression model demonstrated higher accuracy in estimating canopy nitrogen concentration compared to the support vector regression model. (3) Using the random forest algorithm, the average RMSE, NRMSE, and MAE for estimating canopy nitrogen concentration based on effective leaf nitrogen concentration were 0.10%, 4.41%, and 0.07%, respectively. In contrast, the average RMSE, NRMSE, and MAE for estimation based on direct vegetation indices were 0.19%, 9.00%, and 0.15%, respectively. In conclusion, the study identified the spatial differentiation of maize canopy nitrogen concentration. Considering effective leaf nitrogen concentration based on random forest and vegetation index estimation significantly improved the accuracy of canopy nitrogen concentration estimation. The canopy nitrogen concentration estimation framework, which accounts for the spatial heterogeneity of canopy nitrogen concentration, established in this study can provide theoretical support for real-time nitrogen nutrition diagnosis of maize.

Effects of nitrogen reduction and organic fertilizer substitution on dry matter accumulation, translocation, distribution, and yield of dryland winter wheat

ZHANG Jun, HU Chuan, ZHOU Qi-Hui, REN Kai-Ming, DONG Shi-Yan, LIU Ao-Han, WU Jin-Zhi, HUANG Ming, LI You-Jun

Acta Agronomica Sinica. 2025, 51(1):  207-220.  doi:10.3724/SP.J.1006.2025.41025

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The effects of reducing chemical nitrogen and organic fertilizer substitution on dryland winter wheat yield formation and economic benefit were explored to provide a theoretical and technical basis for the implementation of chemical fertilizer reduction and organic fertilizer substitution. A field experiment with four treatments: no nitrogen application (NN), farmer nitrogen application (FN), 20% reduction of N fertilizer based on FN (RN), and organic fertilizer substituting 20% nitrogen of RN (OSN)—was conducted at Mengjin and Luoning, Henan province, typical dryland wheat production system at the intersection of the Loess Plateau and the Huang-Huai-Hai Plain, from 2019 to 2023. The effects of different treatments on dry matter accumulation, translocation, distribution, applied nitrogen dry matter productivity, yield and its components, and economic benefit were analyzed. The results showed the following: (1) Compared with FN, RN reduced dry matter accumulation of wheat at jointing, anthesis, and maturity stages, as well as pre-anthesis dry matter translocation and dry matter distribution in the stem, spike axis+glume, and grain at maturity, but had no significant effect on grain yield. (2) Compared with FN and RN, OSN increased applied nitrogen dry matter productivity at each growth stage, significantly enhancing dry matter accumulation at jointing, anthesis, and maturity stages. OSN also increased pre-anthesis dry matter translocation, post-anthesis dry matter accumulation, and the contribution rate of post-anthesis dry matter accumulation to grain. This led to increased dry matter distribution in all aboveground organs at maturity, resulting in a significant grain yield increase of 15.03% and 17.12%, and an economic benefit increase of 3.84% and 4.23%, respectively. (3) Grain yield was significantly positively correlated with pre-anthesis dry matter translocation, post-anthesis dry matter accumulation, and the contribution rate of post-anthesis dry matter accumulation to grain, and significantly negatively correlated with the contribution rate of pre-anthesis dry matter translocation to grain. In this research, based on nitrogen application amounts of 172 kg hm^-2 (summer fallow-winter wheat) and 192 kg hm^-2 (summer maize-winter wheat) during the wheat season under rain-fed conditions, the OSN treatment improved applied nitrogen dry matter productivity and increased dry matter accumulation at each growth stage. The synergistic increase in pre-anthesis dry matter translocation and post-anthesis dry matter accumulation allowed OSN to achieve the highest yield, making it an optimal fertilizer management practice for high-efficiency and sustainable production of rain-fed dryland winter wheat with a yield level of 5000 kg hm^-2.

Effect of row spacing configuration and density regulation on dry matter production and yield in cotton

XIN Ming-Hua, MI Ya-Di, WANG Guo-Ping, LI Xiao-Fei, LI Ya-Bing, DONG He-Lin, HAN Ying-Chun, FENG Lu

Acta Agronomica Sinica. 2025, 51(1):  221-232.  doi:10.3724/SP.J.1006.2025.34189

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Row spacing configuration and plant density are critical factors influencing cotton yield and fiber quality. In Xinjiang, cotton is primarily planted using a wide-narrow row spacing system, though equal row spacing is also used. However, there is ongoing debate regarding the effectiveness of these two methods. To clarify this, a two-year field experiment was conducted using the cotton variety Zhongmian 88. A split-plot design was employed, with row spacing configurations (equal row spacing and wide-narrow row spacing) as the main plot and planting densities 12×10⁴ plants hm^-2 (D1), 16×10⁴ plants hm^-2 (D2), and 18×10⁴ plants hm^-2 (D3) as the sub-plots. The study aimed to compare the effects of row spacing configuration and plant density on cotton population growth, dry matter accumulation and distribution, as well as yield and fiber quality. The results showed that the growth rate of leaf area index (LAI), the peak LAI, and the proportion of reproductive organ biomass at the boll opening stage were higher in both equal rows spacing and wide-narrow row spacing at intermediate density (16×10⁴ plants hm^-2) compared to the other treatment combinations, with no significant differences between the two configurations. Additionally, no significant differences were found among treatments for cotton growth rate (CGR), net assimilation rate (NAR), and boll growth rate (BGR). Over the two years, seed cotton yields were similar for equal row spacing and wide-narrow row spacing at medium density, with no significant differences in fiber quality. A comprehensive analysis over both years concluded that under medium density, both row spacing configurations can achieve optimal yield and fiber quality. This study provides a scientific basis for selecting row spacing configurations and planting densities for cotton cultivation in Xinjiang.

Response of senescence characteristics for maize leaves under different plastic mulching and using patterns in oasis irrigation areas of northwestern China

WANG Li-Ping, LI Pan, ZHAO Lian-Hao, FAN Zhi-Long, HU Fa-Long, FAN Hong, HE Wei, CHAI Qiang, YIN Wen

Acta Agronomica Sinica. 2025, 51(1):  233-246.  doi:10.3724/SP.J.1006.2025.43022

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In the conventional corn production system of the northwest oasis irrigation area, the extensive use of plastic mulching has resulted in severe environmental pollution, and maize leaves often experience premature senescence under extreme high temperatures. This study investigates the feasibility of delaying maize leaf senescence and increasing yield through the implementation of no-tillage with plastic re-mulching technology. The goal is to offer theoretical support for developing efficient maize production techniques with reduced plastic mulching usage in the northwest oasis irrigation area. In 2013, we established three treatments: no-tillage with plastic re-mulching (NTP), no-tillage in autumn with new plastic mulching in spring (RTP), and conventional tillage with annual new plastic mulching (CTP, as the control). From 2021 to 2023, we examined the effects of these treatments on maize photosynthetic performance, stay-green characteristics, cellular antioxidant enzyme activities, and osmotic regulatory substance contents. The results demonstrated that NTP and RTP effectively regulated the dynamic balance between photosynthetic activity and leaf stay-green performance during the maize growing period. These treatments maintained higher leaf area index (LAI), photosynthetic potential (LAD), stay-green characteristics (SG), and relative chlorophyll content (SPAD) in the late growth stage, which contributed to delayed leaf senescence. Compared with CTP, NTP increased LAI, LAD, SG, and SPAD by 15.1%-16.1%, 14.8%-15.5%, 7.2%-9.2%, and 11.3%-11.7%, respectively, 75-120 days after emergence. Similarly, RTP increased these parameters by 12.4%-13.0%, 11.5%-12.4%, 10.0%-17.6%, and 6.0%-6.7%, respectively. Additionally, fitting the green leaf area per plant revealed that NTP and RTP delayed leaf senescence by 5.8-7.0 days and 6.2-7.7 days, respectively, compared to CTP. This delay in senescence was attributed to enhanced antioxidant capacity and improved osmotic regulation in maize leaves during the bell stage and grain-filling stage. NTP exhibited superior effects, with increases in antioxidant enzyme activities (SOD, POD, CAT, and APX) of 17.6%-20.0%, 28.4%-34.4%, 6.7%-8.4%, and 8.3%-10.9%, respectively, compared to CTP. Likewise, RTP increased these enzyme activities by 11.3%-11.7%, 16.9%-18.2%, 4.4%-6.1%, and 5.8%-7.7%, respectively. Moreover, relative to CTP, soluble protein and proline contents in NTP and RTP increased by 35.9%-43.9% and 29.5%-31.8%, and 20.7%-31.7% and 17.4%-20.4%, respectively, while malondialdehyde content decreased by 26.0%-27.8% and 17.5%-25.9%, respectively. Consequently, NTP increased maize grain yield by 5.2%-6.0% in comparison to CTP. In conclusion, no-tillage with plastic re-mulching is a viable practice for delaying maize leaf senescence and increasing yield, while simultaneously reducing resource inputs in the northwestern oasis irrigation areas.

RESEARCH NOTES

Response of transcription factor StFBH3 under abiotic stress in potato

SONG Qian-Na, SONG Hui-Yang, LI Jing-Hao, DUAN Yong-Hong, MEI Chao, FENG Rui-Yun

Acta Agronomica Sinica. 2025, 51(1):  247-259.  doi:10.3724/SP.J.1006.2025.44044

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The basic helix-loop-helix (bHLH) transcription factor family is the second largest family of transcription factors and plays a central regulatory role in enabling plants to defend against environmental stress. Investigating the function of bHLH family genes in potato can provide a theoretical foundation for potato improvement and breeding. In this study, the StFBH3 gene was cloned, and its tissue-specific expression patterns under different stress treatments were analyzed using qPCR. The relative expression level of StFBH3 was highest in potato roots and leaves, and its expression was induced by osmotic stress, high salinity, and abscisic acid (ABA) treatment. On MS medium containing various concentrations of mannitol, NaCl, and ABA, the chlorophyll content in the StFBH3 overexpressing potato lines was significantly higher than that of the wild type, and the root length was notably longer. Under drought and high salinity conditions, the StFBH3 overexpressing lines cultivated in soil exhibited stronger tolerance compared to the wild type, with significantly higher leaf relative water content, chlorophyll content, and superoxide dismutase (SOD) enzyme activity. Furthermore, qPCR analysis revealed that the expression levels of drought- and salt stress-related genes, such as KAT1, were significantly reduced in the StFBH3overexpressing lines compared to the wild type. These results suggest that StFBH3 functions as a positive regulator, induced and specifically expressed in response to osmotic stress, drought, and high salinity. This study provides an important reference for further analysis of the biological function of the StFBH3 gene in potato.

QTL mapping of tiller angle in qingke (Hordeum vulgare L.)

YANG Jing-Fa, YU Xin-Lian, YAO You-Hua, YAO Xiao-Hua, WANG Lei, WU Kun-Lun, LI Xin

Acta Agronomica Sinica. 2025, 51(1):  260-272.  doi:10.3724/SP.J.1006.2025.31086

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Tiller angle (TA) is a crucial component of qingke (hulless barley) architecture, significantly influencing lodging resistance and grain yield. To investigate the genetic basis of TA, we constructed a high-density genetic linkage map using reduced- representation genome sequencing on recombinant inbred lines (RILs) developed from two parental lines: ‘Dazhangzi’ (characterized by a loose plant architecture) and ‘Kunlun 10’ (characterized by a compact plant architecture). Quantitative trait locus (QTL) mapping was performed based on phenotypic data collected from multiple environments. Additionally, residual hybrid lines (RHLs) derived from the RILs were used to expand the population and fine-map the major QTL, qTA7H-1. A total of nine QTLs associated with TA were identified across seven chromosomes in qingke, with phenotypic variation explained (PVE) ranging from 6.41% to 33.57%. Two QTLs, qTA3H-1 and qTA7H-1, were consistently detected across various environmental conditions, showing average additive effects of 5.42° (increasing TA) and -3.87° (decreasing TA), respectively. Four RHLs were selected within the initial localization interval of qTA7H-1, and F_8:9 near-isogenic lines (NILs) were developed through self-pollination. To further refine the mapping, fourteen pairs of molecular markers were designed and densely placed within the QTL’s confidence interval, targeting the extreme single lines of the RHLs. Ultimately, qTA7H-1 was fine-mapped to a 9.54 Mb physical interval between markers PC08 (32,252,397) and PA10 (41,790,765) using five types of recombinant individuals. Taken together, this study elucidates the genetic factors controlling TA, providing a foundation for genetic improvement and molecular breeding of qingke with optimized architecture.

Effects of maize and soybean intercropping on soil physicochemical properties and microbial carbon metabolism in karst region

QIAN Yu-Ping, SU Bing-Bing, GAO Ji-Xing, RUAN Fen-Hua, LI Ya-Wei, MAO Lin-Chun

Acta Agronomica Sinica. 2025, 51(1):  273-284.  doi:10.3724/SP.J.1006.2025.43010

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This study aimed to investigate the effects of corn and soybean belt intercropping on soil physicochemical properties and microbial community structure diversity in a karst area. Three planting models were established: corn and soybean intercropping (MSI), corn monocropping (MM), and soybean monocropping (SM). The Biolog-ECO microplate method was used to explore the impacts of these different planting patterns on the metabolic activity, diversity, and soil properties of soil microbial carbon sources, as well as their underlying mechanisms. The results showed that compared to MM and SM, the MSI model significantly increased the soil microbial community richness index (McIntosh index) by 11.90% (P < 0.05) and 58.40% (P < 0.01), respectively, and the AWCD value by 24.50% and 80.10%, respectively. The relative absorbance of carboxylic acids, amino acids, and phenolic acids increased significantly by 34.50%, 63.70%, and 61.80% on average, respectively. The carbon source metabolic fingerprint revealed that the MSI model enhanced the utilization of p-carboxylic acid carbon sources by increasing the metabolic activity of itaconic acid, and improved the utilization of amino acid carbon sources by boosting the metabolic activity of L-phenylalanine, L-threonine, and glycyl-glutamic acid. Additionally, the MSI model increased the utilization of polymer carbon sources via enhanced metabolic activity of Tween 40, Tween 80, and liver sugar. Furthermore, soil SOC under MSI treatment was significantly higher by 8.50% and 72.84% compared to MM and SM, respectively, while NH₄⁺-N and TN contents were significantly increased by 46.70% and 33.30% compared to SM treatment, respectively. Principal component analysis revealed that the two extracted components explained 79.69% of the total variation in carbon source utilization. The overall carbon source metabolic capacity followed the order MSI > MM > SM, with the MSI soil microbial community demonstrating the strongest metabolic utilization of carboxylic acids, amino acids, and polymers. Redundancy analysis indicated that TN (53.50%) and SOC (30.90%) were the two most significant environmental factors influencing carbon source metabolic utilization. TN promoted the metabolic utilization of carboxylic acid and amino acid carbon sources, while SOC enhanced the utilization of amine and phenolic acid carbon sources. The preferential carbon metabolism observed in maize and soybean intercropping was primarily driven by the diversity of microbial community structure, and was further regulated by soil total nitrogen and organic matter content. These findings suggest that the interaction between microbial community structure and soil physicochemical properties may play a key role in the yield improvement and efficiency of soybean and corn intercropping systems.