Table of Content

12 May 2026, Volume 52 Issue 5

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REVIEW

Strategies and prospects for large-scale crop yield improvement based on yield gap

Wang Yu-Cheng, Zhang Lu, Liu A-Kang, Huang Jian-Liang, Peng Shao-Bing, Yuan Shen

Acta Agronomica Sinica. 2026, 52(5):  1279-1290.  doi:10.3724/SP.J.1006.2026.53079

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In the context of the “New Round of the 100-Billion-Jin Grain Production Capacity Enhancement Initiative”, large-scale yield improvement has been identified as a core strategic pathway for ensuring national food security in China. Although national grain production has remained high and stable in recent years, further yield increases through cropland expansion are increasingly constrained by limited water and soil resources and growing environmental pressures. Addressing the key scientific questions of “whether major food crops still have room for yield improvement, how large this potential is, and how it can be realized”, research on yield potential and yield gaps provide an essential theoretical and methodological foundation to quantify production potential, identify limiting factors, and design yield-enhancement strategies. This paper systematically reviews recent advances in yield potential assessment and yield gap analysis, revealing the magnitude of untapped yield potential and the dominant constraints across different crops and regions. Based on these insights, differentiated technical pathways for large-scale yield improvement are proposed. In regions with large yield gaps, priority should be given to optimizing crop management practices and resource allocation to accelerate yield gap closure. In contrast, in areas where yield gaps are relatively small, further yield gains rely on breeding innovation, key technological breakthroughs, and cropping system optimization to raise yield ceilings. In addition, this paper analyzes major bottlenecks in the dissemination and application of yield-enhancing technologies, highlighting the persistent disconnect between scientific outputs and on-farm practices that hampers large-scale adoption. Looking ahead, establishing a coordinated and closed-loop framework encompassing yield potential assessment, yield gap diagnosis, technology integration, and on-farm implementation will be critical for translating scientific advances into sustained productivity gains. Through the synergistic advancement of technological innovations and supportive policy and system arrangements, China can continue to enhance its grain production capacity under constraints of limited arable land and environmental resources, thereby strengthening food security and agricultural sustainability.

CROP GENETICS & BREEDING·GERMPLASM RESOURCES·MOLECULAR GENETICS

Genome-wide identification of the maize MAPK gene family and its response to Fusarium verticillioides infection

Sun Shu-Feng, Xu Zhen-Nan, Huang Jia-Xin, Weng Jian-Feng, Li Xin-Hai

Acta Agronomica Sinica. 2026, 52(5):  1291-1308.  doi:10.3724/SP.J.1006.2026.53078

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Fusarium ear rot (FER), caused by Fusarium verticillioides, is one of the most destructive fungal diseases limiting maize (Zea mays L.) production. The mitogen-activated protein kinase (MAPK) cascade is a central regulator of plant growth, development, and stress responses. Previous studies have shown that ZmMAPKs can enhance resistance to fungal pathogens by upregulating defense-related genes and activating key enzymes; however, the roles of individual MAPK family members in pathways associated with FER resistance remain unclear. Here, we conducted a comprehensive analysis of the ZmMAPK gene family, including genome-wide identification and characterization, chromosomal localization, phylogenetic reconstruction, collinearity analysis, promoter cis-element prediction, tissue-specific expression profiling, and expression responses to F. verticillioides infection. In total, 24 MAPK genes were identified in the maize B73 reference genome (V5). Phylogenetic analysis grouped these genes into four subgroups, with highly conserved exon-intron structures within each subgroup. Groups A, B, and C contain the canonical Thr-Glu-Tyr (TEY) activation motif, whereas group D contains the Thr-Asp-Tyr (TDY) motif. Expression analyses showed pronounced tissue-specific differences, suggesting functional diversification within the family. RT-qPCR further indicated that, after F. verticillioides inoculation, ZmMAPK12, ZmMAPK22, ZmMAPK23, and ZmMAPK24 were differentially expressed between the resistant inbred line Qi 319 and the susceptible inbred line B73. Sequence comparisons revealed that, in addition to SNPs, structural variants such as transposon insertions occurred in both promoter and coding regions of these genes. Together, these results suggest that these MAPKs may participate in regulatory pathways controlling maize responses to F. verticillioides infection. This study provides a foundation for elucidating how MAPK cascades contribute to FER resistance and offers candidate genes to support genetic improvement of disease-resistant maize varieties.

Phenotypic evaluation and plasticity analysis of drought resistance in 201 maize inbred lines

Zhang Ning-Ning, Teng Yu-Fei, Ren Na-Na, Wei Xing-Zhuo, Yan Shu-Hao, Fan Ke-Xin, Wang Yong-Hong, Chen Wen-Kang, Zhang Xing-Hua, Zhu Wan-Chao, Xu Shu-Tu, Xue Ji-Quan

Acta Agronomica Sinica. 2026, 52(5):  1309-1325.  doi:10.3724/SP.J.1006.2026.53083

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Drought is the primary constraint limiting maize yield improvement. Phenotypic plasticity describes how a given genotype responds to environmental variation; therefore, evaluating drought plasticity in maize inbred lines is essential. Using drought-resistance-related data for 201 inbred lines evaluated across five environments and two water regimes during 2019-2020, we assessed drought resistance using three approaches, including factor analysis, and classified the lines into four levels: highly resistant (HR), resistant (R), moderately resistant (MR), and weakly resistant (WR). Lines such as KA105, KB020, and Zong 31 showed strong drought resistance. Plasticity was then quantified using the Finlay-Wilkinson (FW) regression, and two drought plasticity patterns were defined: G×E positive plasticity (a genotype shows a significantly better positive response than its overall mean performance in specific environments) and no G×E positive plasticity (a genotype performs stably across environments and does not show a significantly better positive response relative to its overall mean in any environment). KA105 and M1801 were classified as the G×E positive plasticity type, whereas 09B-6-2 was classified as the no G×E positive plasticity type. Overall, KA105 combined strong drought resistance with G×E positive plasticity, indicating that it is a promising germplasm source for drought-resistance breeding with potential for broad application.

Genome-wide analysis of the WOX gene family and identification of candidate genes for adventitious shoot regeneration in peanut

Gu Chun-Miao, Wang Run-Feng, Huang Lu, Liu Hao, Lu Qing, Li Hai-Fen, Li Shao-Xiong, He Shuang-Cheng, Hong Yan-Bin, Chen Xiao-Ping, Tan Bin, Yu Qian-Xia

Acta Agronomica Sinica. 2026, 52(5):  1326-1340.  doi:10.3724/SP.J.1006.2026.55065

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The WUSCHEL-related homeobox (WOX) transcription factor family plays central roles in maintaining stem cell homeostasis and regulating organogenesis in plants. Genetic transformation of peanut (Arachis hypogaea L.), a globally important oilseed crop, remains severely limited by low regeneration efficiency. Here, we conducted a genome-wide identification and characterization of WOX genes in the peanut cultivar ‘Fuhuasheng’ to pinpoint candidates potentially involved in organ regeneration and to provide a basis for overcoming regeneration-related constraints in peanut transformation. We identified 20 WOX genes and systematically analyzed their phylogenetic relationships, conserved domains, collinearity, and promoter features, and then profiled their expression across tissues and during adventitious shoot regeneration using transcriptome data. Phylogenetic analysis clustered the AhWOX genes into three clades (ancient, intermediate, and WUS). All AhWOX proteins contained a conserved homeodomain (HD), and several WUS-clade members also carried the WUS-box and EAR motifs. Collinearity analysis indicated that AhWOX7, AhWOX12, and AhWOX14 are orthologs of Arabidopsis thaliana WUS and WOX5 and of the soybean regeneration-related gene GmWOX18, respectively. However, these orthologs showed only low expression, whereas the ancient-clade genes AhWOX13 and AhWOX20 were consistently highly expressed across all stages of adventitious shoot regeneration. Promoter analysis revealed enrichment of cis-elements associated with meristem activity, and phylogenetic evidence suggested that AhWOX13 and AhWOX20 are orthologous to AtWOX14, a reported positive regulator of shoot regeneration. Collectively, our results highlight AhWOX13 and AhWOX20 as promising candidates for improving regeneration capacity in peanut, providing a framework to enhance peanut transformation and accelerate functional genomics and trait engineering in oilseed crops.

Identification of maize lateral root density genes resources through integrated RNA-seq and BSA-seq analyses

Han Ya-Xin, He Guan-Hua, Zhang Xiao-Qiong, Zhang Deng-Feng, Li Yong-Xiang, Liu Xu-Yang, Wang Tian-Yu, Li Yu, Zou Hua-Wen, Li Chun-Hui

Acta Agronomica Sinica. 2026, 52(5):  1341-1352.  doi:10.3724/SP.J.1006.2026.53070

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As the primary organ responsible for water and nutrient uptake, the root system plays a vital role in maize growth and yield formation. Understanding the genetic basis of root architectural traits—particularly lateral root density (LRD)—is crucial for advancing high-yield breeding strategies. In this study, an F₂ population was developed from a cross between Danhuang 02 (high LRD) and HRB16041 (low LRD). Bulked segregant analysis coupled with high-throughput sequencing (BSA-seq) was conducted to identify genomic loci significantly associated with LRD. In parallel, transcriptome sequencing of lateral root tissues from eight diverse maize inbred lines was performed to explore candidate genes regulating LRD at the seedling stage. BSA-seq identified 240 significantly associated SNPs and 2420 InDels, involving 235 candidate genes located in regulatory regions, alternative splicing sites, or coding sequences. RNA-seq analysis revealed 1979 differentially expressed genes (DEGs) associated with LRD, including 954 up-regulated and 1025 down-regulated genes. Integrated analysis of BSA-seq and RNA-seq data identified 12 overlapping genes as strong candidates for regulating LRD. qRT-PCR validation suggested that Zm00001d033708 and Zm00001d045720 may act as positive regulators of lateral root density, while Zm00001d040375 may function as a negative regulator. This study provides valuable genetic resources and candidate genes for understanding and improving lateral root development in maize.

Genetic diversity analysis of nationally approved maize varieties in different ecological regions

Yang Yang, Chang Shi-Hui, Tian Hong-Li, Yi Hong-Mei, Wang Lu, Ren Jie, Fan Ya-Ming, Liu Ya-Wei, Wang Feng-Ge, Zhao Jiu-Ran

Acta Agronomica Sinica. 2026, 52(5):  1352-1364.  doi:10.3724/SP.J.1006.2026.53086

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Analyzing the genetic diversity of maize varieties approved at the national level across different ecological regions reveals patterns of genetic differentiation among regional germplasms. This provides a theoretical basis for elite germplasm screening and region-specific variety breeding. In this study, 273 nationally approved common maize varieties were analyzed. Sixteen field phenotypic traits and genetic variation parameters based on 40 SSR markers were statistically evaluated. Cluster analysis and association analysis of phenotypic and genotypic data were conducted to explore the relationships among phenotypes, genotypes, and environmental factors in common maize. The results showed significant differences in growth period and regional trial yield across ecological regions, with F values of 2484.95 and 472.83, respectively. Genetic diversity was relatively high in the Xi-Nan spring-sowing region (XN), with a gene diversity index of 0.72. Phenotypic clustering divided 325 variety records into four groups: Group X1 mainly included varieties from the Dong-Hua-Bei (DHB) and Xi-Bei (XB) spring-sowing regions; Group X2 was dominated by varieties from the Bei-Fang (BF) early-maturity spring-sowing region; Group X3 included varieties from the XN region; and Group X4 mostly comprised varieties from the Huang-Huai-Hai (HHH) summer-sowing and Dong-Nan (DN) spring-sowing regions. Phenotypic differentiation among ecological regions followed clear trends: DHB and XB varieties were characterized by medium-late maturity and tall stalks; BF by early maturity and medium short stalks; XN by medium maturity and medium stalks; and HHH and DN by early maturity and medium stalks. Notably, XN, HHH, and DN regions experienced relatively high disease pressure. Principal component analysis (PCA) of phenotypic traits showed that the first two components explained 69.0% of the total variance, with clear group separation, supporting the validity of the phenotypic classifications. Genotypic clustering also divided the 273 varieties into four groups. In Group Y1, the predominant heterosis patterns were Reid × X and Improved Reid × X; in Group Y2, X × Tangsipingtou (Huangzaosi-derived lines); and in Group Y4, Improved Reid × Tangsipingtou. Genotypic PCA demonstrated a cumulative contribution of 57.9% from the first two components, with clear intra-group cohesion and significant inter-group differentiation, confirming the reliability of the genotypic groupings. Association analysis between genotypes and phenotypes revealed a weak correlation, likely due to the design objectives of molecular marker selection. Maize varieties from different ecological regions in China exhibit distinct regional differentiation in field performance and parental heterosis groups, resulting in a well-defined correspondence among ecological zones, trait expression, and genetic background. This pattern reflects region-specific breeding goals that prioritize yield stability and efficient resource utilization.

Identification and cloning of SVN7 controlling small vascular bundle number in the rice flag leaf

Yan An, Jiang Kun-Wei, Wang Rong-Yuan, Tian Lin, Zhang Lu, Wang Yun, Xu Jian-Long

Acta Agronomica Sinica. 2026, 52(5):  1364-1372.  doi:10.3724/SP.J.1006.2026.52045

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Leaf vascular bundles play a crucial role in the transport of photosynthates, and their number, size, and capacity directly affect transport efficiency. Here, we performed a genome-wide association study (GWAS) of small vascular bundle number (SVN) in the flag leaf using 307 rice cultivars and identified SVN7, an allele of OsBZR1. A SVN7 knockout mutant was generated using CRISPR/Cas9. The flag-leaf SVN of svn7 mutants was significantly higher than that of the wild-type Zhonghua 11 (ZH11), indicating that SVN7 negatively regulates small vascular bundle number. Compared with ZH11, svn7 mutants also showed significantly increased numbers of large and small vascular bundles in the panicle neck, increased flag-leaf width, and increased grain number per panicle, whereas plant height and grain weight were significantly reduced. These results indicate that SVN7 has pleiotropic effects and coordinately regulates source-, sink-, and flow-related traits. Among the 307 accessions, the superior haplotype Hap1 was associated with higher flag-leaf SVN, wider flag leaves, more grains per panicle, and higher yield per plant. This haplotype may be useful for molecular design breeding to develop new high-yield rice varieties.

Comprehensive evaluation of low-iron tolerance and screening of elite germplasm at the soybean seedling stage

Yao Shu, Guo Kai-Yue, Zhai Hui-Hui, Yao Jia-Hui, Deng Wen-Qi, Yan Ling, Huang Chi, Gao Yang, Yu Yan-Ran, Zhao Zhen-Bang, Li Ying-Hui, Wang Xiao-Bo, Li Jia-Jia

Acta Agronomica Sinica. 2026, 52(5):  1373-1387.  doi:10.3724/SP.J.1006.2026.55066

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Iron is an essential micronutrient for plant growth, and limited iron availability in soils can directly cause iron deficiency. Soybean seedlings are particularly sensitive to iron deficiency, which markedly affects their growth and development. Here, we evaluated 130 soybean germplasm accessions under two hydroponic iron regimes: low iron (1 μmol L^-1, LFe) and normal iron (25 μmol L^-1, CK). At the second fully expanded trifoliolate stage, relative chlorophyll content, plant height, leaf area, main root length, stem and leaf fresh weight, and root mean diameter were measured, among other traits. Compared with CK, low-iron stress reduced relative chlorophyll content, leaf area, and stem-and-leaf fresh weight by > 20%, and decreased nine additional indices (including plant height and main root length) by > 10%. Overall, low iron significantly inhibited both shoot and root growth. Principal component analysis (PCA) of low-iron tolerance coefficients transformed the 13 indices into four principal components. A comprehensive low-iron tolerance D value was then calculated using a standardized membership function approach, and cluster analysis based on D classified the accessions into five grades: grade I (tolerant, 12 accessions), grade II (strongly tolerant, 48), grade III (moderate, 47), grade IV (strongly sensitive, 16), and grade V (sensitive, 7). Stepwise regression was used to develop a predictive model for seedling low-iron tolerance: D = -0.486+0.178X1+ 0.262X2+ 0.072X3+ 0.189X4+ 0.124X5+ 0.091X6+0.065X7+ 0.064X8+ 0.118X9. This model identified nine core indicators—including relative chlorophyll content, plant height, and leaf area—as key traits for evaluating low-iron tolerance at the soybean seedling stage. These results provide a basis for identifying iron-tolerance-related functional genes and for improving iron-use efficiency in soybean.

Screening and phenotypic characterization of EMS-induced mutants with elite agronomic traits in broomcorn millet

Zhang Ying-Xing, Bheel Chander Kumar, Song Yu-Zhen, Wang Yue, Cao Yue, Khound Rituraj, Santra Dipak Kumar, Cao Xiao-Ning, Wang Rui-Yun

Acta Agronomica Sinica. 2026, 52(5):  1388-1400.  doi:10.3724/SP.J.1006.2026.54134

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Ethyl methanesulfonate (EMS) mutagenesis is an effective approach for creating genetic diversity in broomcorn millet (Panicum miliaceum L.) and for developing novel mutant lines with improved agronomic traits. Using the landrace ‘Heishuzi’ as the starting material, we conducted a two-factor completely crossed experimental design with six EMS concentrations (0, 0.4%, 0.6%, 0.8%, 1.0%, and 1.2%) and five soaking durations (6, 8, 10, 12, and 14 h), yielding 30 treatment combinations. EMS significantly inhibited seed germination, and germination rate decreased progressively with increasing EMS concentration and longer soaking duration. Based on phenotypic variation, 18 distinct mutant phenotypes were identified, including dwarf, compact panicle, leaf-color variants, early maturity, and single tillering. In the M₂ population, 297 mutant plants were recovered (mutation frequency, 28.89%); dwarf mutants were the most common (35 plants), whereas single-tillering mutants were the least frequent (5 plants). In the M₃ population, 215 mutant plants were obtained (mutation frequency, 20.91%), with early-maturing mutants being the most abundant (35 plants) and single-tillering mutants remaining relatively rare (6 plants). In addition, 215 M₃ lines were genotyped with 85 broomcorn millet-specific SSR markers; 12 markers with clear amplification and high polymorphism were selected, and 44 mutant plants were identified (variation frequency, 4.3%). Electrophoretic banding patterns indicated 32 mutants with additional bands, 6 with missing bands, and 6 with locus variation. Agronomic evaluation of these mutants identified 1 compact-panicle plant, 21 dwarf plants (60-70 cm in height), 11 early-maturing (55-60 days) plants, and 2 single-tillering plants. Collectively, these results provide valuable germplasm resources for genetic improvement and breeding in broomcorn millet.

Development of a deep learning-based image recognition system for major wheat diseases

He Wan-Long, Geng Hong-Wei, Zhang Fei-Fei, Mikereayi·Ababaikere , Luo Zi-Yang, Li Peng-Cheng, Zhou Zhao-Yu, Cheng Yu-Kun

Acta Agronomica Sinica. 2026, 52(5):  1401-1417.  doi:10.3724/SP.J.1006.2026.51089

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Traditional methods for wheat disease identification rely heavily on manual surveys, which are labor-intensive and time-consuming. To address these limitations, this study proposes a recognition model, CBAM-MobileNet-V2, based on an enhanced MobileNet-V2 architecture. Designed for deployment on Android mobile platforms, the model provides agricultural practitioners with a fast, accurate, and user-friendly tool for in-field wheat disease diagnosis. The model offers several key advantages. First, it employs transfer learning to facilitate efficient feature extraction. Second, residual connections are integrated into the core feature extraction modules to enhance learning capacity, while average pooling layers within the inverted residual blocks are used for effective downsampling. Additionally, the CBAM attention mechanism is incorporated to further improve feature extraction and overall model performance. The optimal performance is achieved with a regularization coefficient of 0.005 and a learning rate of 0.010. The model is trained using the AdamW optimizer, which enhanced convergence and generalization. CBAM-MobileNet-V2 has a compact size of only 9.69 Mb and achieves an accuracy of 97.95%, representing a 12.59% improvement over the original MobileNet-V2. Compared to other lightweight neural networks—such as EfficientNet-B0, MNASNet, MobileNet-V2, ResNet-18, ShuffleNet-V2, and SqueezeNet—CBAM-MobileNet-V2 demonstrates superior recognition accuracy while maintaining a lower parameter count, highlighting its efficiency and suitability for practical applications. The deep learning-based recognition system successfully identifies seven common wheat diseases with high accuracy. Its offline, real-time detection capability eliminates the need for cloud deployment, thereby reducing user costs and supporting intelligent wheat disease diagnosis in resource-limited environments.

Molecular mechanisms of exogenous quercetin in enhancing cold resistance in tea plants

Xu Miao-Miao, Di Tai-Mei, Wang Jie, Wu Ye-Die, Liu En-Bei, Wang Yu-Chun, Wang Xin-Chao, Wang Lu

Acta Agronomica Sinica. 2026, 52(5):  1418-1429.  doi:10.3724/SP.J.1006.2026.54137

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Extreme weather events, such as spring cold spells, pose a serious threat to tea production by reducing both yield and quality. Quercetin is a flavonoid widely distributed in plants and plays important antioxidant and signaling roles in responses to abiotic stresses. To evaluate the effects of quercetin on cold resistance in tea shoots and to elucidate the underlying mechanisms, Camellia sinensis cv. “Longjing 43” plants were foliar-sprayed with exogenous quercetin at different concentrations (0.1 μg mL^-1 and 0.5 μg mL^-1). Physiological traits and gene expression in tea shoots under cold stress were subsequently assessed. Cold stress markedly induced quercetin accumulation in young shoots, and exogenous quercetin significantly enhanced the cold resistance of young shoots. Compared with the control, quercetin-treated shoots showed higher maximum photochemical efficiency (F_v/F_m), lower relative electrolyte leakage, malondialdehyde, and hydrogen peroxide contents, and increased antioxidant enzyme activities under cold stress. Transcriptome analysis further indicated that quercetin significantly upregulated genes involved in hormone signaling, calcium signaling, and MAPK signaling pathways under cold stress. Collectively, these results suggest that quercetin enhances cold resistance in tea shoots by activating cold signal transduction and inducing downstream stress-responsive genes.

Dynamic transcriptome analysis and key gene discovery during cassava branching development

Cai Zhao-Qin, He Guan-Yong, He Wen, Ruan Li-Xia, Liang Zhen-Hua, Li Yong-Zhen, Li Heng-Rui, Chen Hui-Xian

Acta Agronomica Sinica. 2026, 52(5):  1430-1441.  doi:10.3724/SP.J.1006.2026.54123

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Branching is a key trait that determines plant architecture and yield in cassava. However, its molecular regulatory mechanisms remain unclear. In this study, we used the multi-branching cassava cultivar SC5 as material. We systematically analyzed the regulatory network of cassava branching by measuring phytohormone levels at different developmental stages and integrating transcriptome sequencing analysis. The results showed that during cassava branching, the contents of auxin and cytokinin continuously decreased. Gibberellin content initially increased and reached a peak value at the stage of axillary bud activation, and then decreased. Correspondingly, the expression of genes involved in auxin biosynthesis and signaling transduction were consistently down-regulated. Meanwhile, the gibberellin-related genes were significantly up-regulated. Furthermore, seven key transcription factors were identified, including MeTCP (2), MeMADS (2), MeAP2 (1), MeHD-ZIP (1), and MeERF (1). Their expression patterns were closely associated with branching development. In conclusion, branching development in cassava was coordinately regulated by the dynamic balance of phytohormones and a multi?layered transcriptional regulatory network.

Transcriptome sequencing-based analysis on the formation mechanism of fiber micronaire differences between two sister lines derived from Gossypium hirsutum-G. barbadense hybrid

Zhang Xi, Wang Guang-En, Li Shao-Qi, Liu Yi, Li Jun-Lan, Qian Yu-Yuan

Acta Agronomica Sinica. 2026, 52(5):  1442-1458.  doi:10.3724/SP.J.1006.2026.54110

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The fiber micronaire is a comprehensive index for characterizing the fineness and maturity of cotton fibers. However, high micronaire value hinders the production of high-count yarns in textiles. Reducing the micronaire remains a major challenge in breeding high-quality cotton cultivars. In this study, transcriptome sequencing was conducted on the fibers of sister lines derived from Gossypium hirsutum-G. barbadense hybrid, namely LM (line with low micronaire value) and HM (line with high micronaire value), at 15, 20, 25, and 30 days post anthesis (DPA), respectively. These two lines exhibited highly significant differences in micronaire values, while showing no significant differences in fiber length or strength. The mechanisms underlying the micronaire variation were investigated from multiple perspectives, including cellular structure, phytohormones, cellulose synthesis, and gene expression. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis and hormone quantification suggested that auxin is likely the key plant hormone influencing secondary wall development in both LM and HM lines. Observations of fiber structure, measurements of cellulose content, and KEGG pathway analysis indicated that the orientation and arrangement of cellulose microfibrils may play a more critical role in determining micronaire than cellulose metabolism itself. This developmental process relies on coordinated biological events, including cellulose biosynthesis, cellulose synthase complex (CSC) formation, and the precise localization and dynamic adjustment of microtubules, actin filaments—all of which are modulated by auxin. Additionally, the differentially expressed genes related to cell content degradation may contribute to the differences in lumen size between mature LM and HM fibers. The identified metabolic pathways and differentially expressed genes provide a theoretical basis and genetic resources for breeding cotton varieties with optimized micronaire values suited for textile applications.

TILLAGE & CULTIVATION·PHYSIOLOGY & BIOCHEMISTRY

Effects of dynamic changes in leaf functional nitrogen on photosynthetic rate and photosynthetic nitrogen use efficiency in Brassica napus

Ren Yi-Han, Zhao Man-Li, Dai Jing, Li Yin-Shui, Gu Chi-Ming, Yang Lu, Du Xue-Zhu, Hu Wen-Shi, Qin Lu

Acta Agronomica Sinica. 2026, 52(5):  1459-1471.  doi:10.3724/SP.J.1006.2026.55058

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Rapeseed (Brassica napus L.) is China’s leading oilseed crop, and high yield depends heavily on nitrogen (N) fertilizer inputs; however, nitrogen use efficiency remains relatively low. Rapeseed biomass is primarily derived from photosynthesis. Enhancing the net photosynthetic rate (P_n) and photosynthetic nitrogen use efficiency (PNUE) may provide a feasible approach to simultaneously improve yield and nitrogen use efficiency, thereby reducing N fertilizer application, increasing rapeseed production, and supporting sustainable development of the rapeseed industry. Here, we conducted a hydroponic experiment with different N levels using two rapeseed germplasms that differed significantly in leaf area and P_n. During leaf development, we quantified dynamic changes in leaf N content, photosynthetic capacity, functional N fractions, and ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) characteristics to elucidate how N allocation regulates P_n and PNUE. Leaf N content declined with growth, but P_n did not decrease consistently, and P_n increased with higher N supply. Photosynthetic N (N_psn) and storage N (N_store) were the dominant components of leaf N, accounting for 83.12%-97.61%. During leaf expansion, N_psn changed little whereas N_store declined markedly, which helped maintain P_n at lower total leaf N and improved PNUE. When leaf N content fell below 1.77 g m^-2, both N_psn and N_store decreased linearly, leading to significant reductions in P_n and PNUE. During leaf senescence, the decline in N_psn was 6.24%-19.07% greater than that of N_store, resulting in pronounced decreases in both P_n and PNUE. Rubisco content was significantly and positively correlated with N_psn. The germplasm Yunyou 9, which had higher P_n, showed higher N_psn and Rubisco content than Fuyou 3, which had larger leaf area, with increases of 5.63%-40.37% and 0.38%-38.02%, respectively. Both N_psn and N_store increased with increasing N supply, and P_n increased with N_psn. Overall, during leaf development, Rubisco helped maintain N_psn while N_store declined, supporting higher P_n and improved PNUE. Therefore, optimizing within-leaf N allocation by precisely regulating Rubisco content may be an effective strategy to further enhance rapeseed photosynthetic capacity and nitrogen use efficiency.

Effects of plowing and green manure returning in winter fallow period on soil physicochemical properties and yield in continuously cropped peanut

Zhang Si-Si, Zhao Xiang-Hui, Zhou Yang, Yao Yun-Feng, Zhu Rong-Yu, Dong Yuan-Jie, Hu Guo-Qing, Xu Tong, Liu Zhao-Xin

Acta Agronomica Sinica. 2026, 52(5):  1472-1486.  doi:10.3724/SP.J.1006.2026.55046

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This study aimed to clarify how different tillage practices and green manure incorporation during the winter fallow period affect soil physicochemical properties and peanut yield under continuous cropping, and to identify the optimal agronomic measure for alleviating obstacles associated with continuous spring peanut cropping. Field experiments were conducted from 2022 to 2024 at the agricultural experiment station of Shandong agricultural university. Under continuous peanut monocropping, three treatments were established: no tillage after peanut harvest (no-tillage, MG); plowing after harvest followed by ryegrass planting until the following year’s heading stage and then incorporation as green manure (green manure returning, YQ); and plowing plus soil drying after harvest (plowing tillage, FG). Soil physical properties, nutrient status, enzyme activities, and peanut yield were monitored throughout all growth stages of the subsequent peanut season. Compared with MG, both YQ and FG significantly improved soil physical condition at the pod-filling stage, decreasing bulk density (BD) by 5.39% and 2.31% and increasing soil porosity (SP) by 9.62% and 5.84%, respectively. Both treatments also increased the proportion of macroaggregates (> 5 mm, 2-5 mm, and 1-2 mm) in the 0-30 cm soil layer. Moreover, YQ significantly increased total nitrogen (TN) and organic matter (OM) contents, as well as sucrase (SA) and urease (UA) activities, in both the 0-20 cm and 20-40 cm layers across all growth stages. Over two years, pod yield under YQ and FG increased by 18.85% and 9.22%, respectively, and kernel yield increased by 12.21% and 3.21%, respectively, relative to MG; these gains were mainly driven by an increase in pods per plant. Pod yield was positively correlated with TN, OM, UA, and SA, but negatively correlated with BD. Overall, both YQ and FG are effective practices for mitigating continuous-cropping constraints in peanut by improving soil physicochemical properties, enhancing nutrient availability, and increasing hydrolytic enzyme activities, with YQ showing greater benefits than FG.

Photosynthetic characteristics of 20% reduced irrigation combined with 25% organic substitution for chemical fertilizer in increasing silage maize yield

Zhang Hong-Rong, Wang Fei-Er, Li Pan, Qiu Hai-Long, Zhu Jing, Zhao Lian-Hao, Nan Yun-You, He Wei, Fan Zhi-Long, Hu Fa-Long, Chai Qiang, Yin Wen

Acta Agronomica Sinica. 2026, 52(5):  1487-1500.  doi:10.3724/SP.J.1006.2026.53071

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In response to the issues of excessive irrigation and fertilizer use, resource waste, and low yield in silage maize production in the oasis irrigation regions of Northwest China, this study investigates the photosynthetic mechanisms underlying yield improvement through reduced irrigation combined with optimized organic substitution for mineral fertilizer. The objective is to provide a scientifically based irrigation and nutrient management strategy for efficient silage maize cultivation in arid irrigated areas. A two-factor split-plot field experiment was conducted in Wuwei city, Gansu province, beginning in 2020. The irrigation treatments included I1 (20% reduction in conventional irrigation, 324 mm) and I2 (conventional irrigation, 405 mm), while the fertilization treatments comprised five levels: F1 (100% chemical nitrogen fertilizer), F2 (25% organic substitution), F3 (50% organic substitution), F4 (75% organic substitution), and F5 (100% organic fertilizer). From 2022 to 2024, data were collected on leaf area index (LAI), leaf area duration (LAD), photosynthetic parameters, chlorophyll fluorescence, and yields of fresh forage (FY) and hay (HY) to evaluate treatment effects. Results showed that substituting 25% of chemical nitrogen with organic fertilizer (I1F2) significantly improved both fresh and hay yields, outperforming other substitution ratios. Compared with I2F1, I1F2 increased fresh and hay yields by 5.0% and 13.8%, respectively. This treatment also enhanced mean LAI, total LAD, and PSII electron transport rate (ETR) by 11.5%, 40.8%, and 17.2%, respectively. Furthermore, net photosynthetic rate (P_n) increased by 15.9%, intercellular CO₂ concentration (C_i) decreased by 12.6%, stomatal conductance (G_s) improved by 7.8%, and non-regulated energy dissipation (Y(NO)) declined by 14.7%. The yield increase was primarily attributed to synergistic improvements in LAI, LAD, SPAD, ETR, P_n, and G_s, leading to enhanced leaf photosynthetic performance. Therefore, a 20% reduction in irrigation combined with 25% organic substitution for mineral nitrogen represents an effective strategy for improving silage maize yield and water use efficiency in northwest irrigated regions.

Optimized water-nitrogen synergy enhances winter wheat yield and nitrogen use efficiency in clay-loam fluvo-aquic soils of southeastern Henan, China

Wang Zhuang-Zhuang, Wu Zi-Jun, Zhang Yong-Xin, Zhang Xin-Yuan, Yuan Li-Xue, Chen Ru-Xue, Liu Shi-Ju, Duan Jian-Zhao, Feng Wei, Wang Tong-Chao, Wang Yong-Hua

Acta Agronomica Sinica. 2026, 52(5):  1501-1521.  doi:10.3724/SP.J.1006.2026.51084

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To reduce yield variability and improve nitrogen use efficiency in winter wheat grown on clay loam fluvo-aquic soils in southeastern Henan—where uneven precipitation and excessive N inputs are common—we conducted a two-year split-plot field experiment. Main plots included two water regimes: rainfed (W0) and supplemental irrigation at both jointing and anthesis (W2; 75 mm per event). Subplots included five N rates: 0, 180, 240, 300, and 360 kg hm^-2 N (N0-N4). We assessed the combined effects of water and N on dry matter accumulation, N utilization, and grain yield. W2 significantly increased post-anthesis dry matter assimilation; compared with W0, dry matter accumulation from anthesis to filling increased by 32.2%, and total dry matter accumulation increased by 28.1%. In parallel, N uptake efficiency and the partial factor productivity of N increased by 26.7% and 25.5%, respectively. Water-N interactions synergistically regulated pre-anthesis N translocation and post-anthesis assimilate partitioning, thereby improving all three yield components. Under the optimal combination (W2N2), spike number, grains per spike, and thousand-grain weight reached 615.0 × 10⁴ hm^-2, 43.9 grains spike^-1, and 45.6 g, respectively. Relative to the traditional high-N practice (W2N4), grains per spike and thousand-grain weight increased by 2.0% and 2.3%, respectively; relative to rainfed with reduced N (W0N2), spike number and grains per spike increased by 11.1% and 34.6%, respectively. These results indicate that W2 increased yield mainly by increasing spike number and grains per spike, whereas reducing N to N2 optimized grains per spike while maintaining a relatively high thousand-grain weight on the basis of stable spike number, forming a synergistic yield strategy characterized by “spike number as the foundation, grains per spike as the driver, and thousand-grain weight stabilization.” This strategy produced the highest yield (9331.8 kg hm^-2) and increased the partial factor productivity of N and agronomic N use efficiency by 61.2% and 67.9%, respectively, compared with 360 kg hm^-2 N. Regarding soil environmental effects, supplemental irrigation altered the vertical distribution of nitrate-N, decreasing residual nitrate by 23.4% in the 0-40 cm layer but increasing it by 32.2% in the 40-100 cm layer, suggesting that irrigation optimization alone may promote downward N movement. However, combining W2 with N reduction to N2 reduced cumulative nitrate-N in the 0-100 cm profile by 26.9%, thereby mitigating leaching risk. Overall, applying 75 mm supplemental irrigation at jointing and anthesis together with 240 kg hm^-2 N provides an effective water-N management strategy that synchronously improves yield and N use efficiency for winter wheat production in the clay loam fluvo-aquic soil region of southeastern Henan.

Yield formation of wheat with different ear types under water-saving supplementary irrigation conditions

Zhang Zhen, Feng Lian-Jie, Shi Yu, Yu Zhen-Wen, Zhang Yong-Li

Acta Agronomica Sinica. 2026, 52(5):  1522-1535.  doi:10.3724/SP.J.1006.2026.51076

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To investigate the effects of water-saving supplemental irrigation on photosynthesis, senescence, and grain filling characteristics of flag leaves in tillers of wheat varieties with different spike types, and to elucidate the physiological mechanisms underlying yield formation under supplemental irrigation, an experiment was conducted using two wheat varieties: the medium-spike Jimai 22 (J22) and the large-spike Shannong 23 (S23). Three irrigation regimes were applied: no irrigation throughout the growing season (W0); water-saving supplemental irrigation (W70), which maintained 70% relative soil moisture in the 0-40 cm layer at both the jointing and flowering stages; and full supplemental irrigation (W90), which maintained 90% relative soil moisture at the same stages and depth. A total of six treatment combinations were evaluated to compare photosynthetic performance senescence characteristics of flag leaves on tillers, and grain filling parameters between the two spike-type varieties. Results showed that under water-saving supplemental irrigation, S23 exhibited higher relative chlorophyll content, net photosynthetic rate, sucrose content, superoxide dismutase activity, and soluble protein content in the flag leaves of tillers after flowering, along with lower malondialdehyde content, compared with other treatments. Additionally, the average grain filling rate, maximum grain filling rate, and duration of the active grain filling period were significantly higher, contributing to a significantly greater grain weight. Under water-saving supplemental irrigation, the single-plant grain yield of S23 increased by 8.39% to 45.16%, and the grain yield per hectare increased by 5.76% to 44.32%, compared with other treatments. Although no significant yield difference was observed between the water-saving and fully irrigated S23 treatments, the total irrigation volume under water-saving irrigation was 14.82% to 52.61% lower, while irrigation water use efficiency was 22.33% to 122.74% higher, In conclusion, the water-saving supplemental irrigation treatment for S23 achieved higher grain yield and the highest irrigation efficiency by enhancing the accumulation of photosynthetic products in tillers and their branches, making it the most effective treatment under the experimental conditions.

Biochar combined with chemical fertilizer increases maize yield and soil ecosystem multifunctionality in an intercropped maize-soybean

Guo Xing-Yu, Hu Dan, Lin Su-Qi, Wang Meng-Kai, Tan Wen-Feng, Huang Chuan-Qin

Acta Agronomica Sinica. 2026, 52(5):  1536-1547.  doi:10.3724/SP.J.1006.2026.53082

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To investigate the effects of biochar addition on maize growth and soil ecosystem multifunctionality in a maize-soybean intercropping system, a two-year field experiment was conducted in Xianning City, Hubei Province, from 2023 to 2024. The study examined two planting patterns—monoculture maize (MM) and intercropped maize and soybean (SM)—and two fertilization regimes—conventional chemical fertilizer (CF) and biochar combined with chemical fertilizer (BF). Parameters assessed included maize growth, soil physicochemical properties, microbial diversity, and ecosystem multifunctionality. In terms of cropping system, compared with monoculture maize, intercropping significantly increased maize root length density in the 0-30 cm soil layer by 21.58%-32.24%, reduced soil bulk density by 6.31% in the 10-20 cm layer, increased soil organic carbon content by 3.51% and 13.01% in the 0-10 cm and 20-30 cm layers, respectively, and raised total nitrogen content by 8.96% and 12.13% in the 10-20 cm and 20-30 cm layers, respectively. In terms of fertilizer treatment, compared with conventional chemical fertilizer, the combination of biochar and chemical fertilizer increased maize root length density by 5.84%-11.42% in the 0-30 cm layer, reduced soil bulk density by 4.77% in the 10-20 cm layer, and increased soil organic carbon content by 4.54% and 14.11% in the 0-10 cm and 20-30 cm layers, respectively. Relative to MM-CF, intercropping with chemical fertilizer (SM-CF) increased maize equivalent yield by 33.56%, and enhanced the soil ecosystem multifunctionality index by 101.63%-119.91% in the 0-30 cm layer. Intercropping with biochar and chemical fertilizer (SM-BF) further increased equivalent yield by 49.24% and boosted the multifunctionality index by 134.59%-238.63%. A random forest model identified root biomass as the most influential factor affecting soil ecosystem multifunctionality. These findings suggest that biochar combined with chemical fertilizer improves soil structure, enhances nutrient accumulation, and increases microbial diversity by promoting maize root growth under intercropped conditions, thereby synergistically enhancing both maize yield and soil ecosystem functions, and contributing to sustainable agricultural development.

Long-term stubble return and subsoiling enhance cotton yields in coastal saline-alkali soils by improving soil conditions and photosynthetic characteristics

Zhao Jia-Xue, Zhou Long-Hao, Guo Qi-Yuan, Shang Lun-Xiao, Wang Han, Liu Zhi-Tao, Chen Xi, Zhang Xiao-Pei, Song Xian-Liang, Ahmedov Miraziz Baltaevich, Mao Li-Li

Acta Agronomica Sinica. 2026, 52(5):  1548-1560.  doi:10.3724/SP.J.1006.2026.54113

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Stubble returning and subsoiling are agronomic practices used to ameliorate saline-alkali soils, while photosynthesis is a fundamental physiological process underpinning crop yield formation. Long-term implementation of stubble returning and subsoiling can improve soil fertility in coastal saline-alkali cotton fields, thereby promoting cotton growth and yield. However, the photosynthetic response of cotton to long-term conservation tillage under saline-alkali conditions remains insufficiently understood. To investigate the effects of long-term conservation tillage on soil physicochemical properties, cotton photosynthetic performance, dry matter accumulation, nutrient uptake, and lint yield in coastal saline-alkali fields, four treatments were established: conventional tillage (CK), subsoiling (S), stubble returning (R), and the combination of stubble returning and subsoiling (RS). The results showed that, compared with CK, the RS treatment significantly reduced soil pH by 6.6%-7.7% and soil salt content by 21.2%-26.1% (P < 0.01). At full bloom and boll-setting stages, net photosynthetic rate (P_n), stomatal conductance (G_s), and relative chlorophyll content (SPAD value) increased by 15.9%, 42.9%, and 12.7%, respectively (P < 0.05). During the boll-opening period, canopy photosynthetically active radiation (PAR), dry matter accumulation, and nitrogen uptake increased by 11.8%, 59.8%, and 72.0%, respectively (P < 0.05). Moreover, lint yield increased by 56.2% (P < 0.01). Lint yield was significantly positively correlated with transpiration rate (T_r), stomatal conductance (G_s), and PAR (r > 0.5, P < 0.05). In conclusion, long-term stubble returning and subsoiling effectively improve the soil environment in saline-alkali fields, enhance cotton photosynthetic capacity, and significantly increase lint yield. This integrated conservation tillage strategy offers a practical and effective approach to promoting cotton growth and improving productivity in coastal saline-alkali regions.

Physiological mechanisms of methyl jasmonate (MeJA) alleviating the effects of heat stress on ear differentiation in maize

Liu Xin-Meng, Ren Hao, Zhang Ji-Bo, Zhang Ji-Wang, Zhao Bin, Ren Bai-Zhao, Liu Peng, Wang Hong-Zhang

Acta Agronomica Sinica. 2026, 52(5):  1561-1572.  doi:10.3724/SP.J.1006.2026.53068

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Global warming has increased the frequency and severity of heat stress during the maize growing season in the Huang-Huai-Hai Plain of China, which can markedly hinder young ear development and cause substantial yield losses in summer maize. Methyl jasmonate (MeJA) is a biologically active compound that can alleviate abiotic stress and promote reproductive development, and thus represents a promising exogenous regulator for improving crop stress responses. This study aimed to clarify the effects of MeJA on young ear differentiation, fertilization, and seed-setting traits during the floret differentiation stage under heat stress. The summer maize cultivar Xianyu 335 was used as the experimental material. Exogenous MeJA was applied by foliar spraying at two key stages of ear differentiation (V9, 9th leaf stage; V12, 12th leaf stage) under simulated heat-stress conditions. By quantifying endogenous hormones and antioxidant responses, we elucidated how MeJA regulates ear morphology, floret number, and fertilization and seed-setting characteristics under heat stress. Exogenous MeJA significantly increased the contents of trans-zeatin+trans-zeatin riboside, salicylic acid, and jasmonic acid in young ears while reducing abscisic acid content. Compared with the control, MeJA also increased superoxide dismutase, peroxidase, and catalase activities in young ears and reduced malondialdehyde accumulation, thereby enhancing stress tolerance and mitigating heat stress-induced damage. Accordingly, MeJA increased young ear length, diameter, and floret number by 5.54%-48.88%, 12.34%-24.41%, and 2.51%-25.51%, respectively, and reduced the length of the undeveloped ear portion by 10.26%-50.00%. In addition, MeJA significantly increased the number of exposed silks and the floret fertilization rate while decreasing the grain abortion rate, resulting in marked increases in kernels per ear (48.36%-57.23%) and grain yield (49.14%-66.79%). Overall, MeJA alleviated heat stress-induced inhibition of ear differentiation by modulating endogenous hormone status and activating the antioxidant system in young ears, thereby reducing oxidative damage and improving fertilization and seed-setting capacity. These findings provide a theoretical basis for developing heat stress-resilient cultivation practices and stabilizing summer maize yield.

RESEARCH NOTES

Genome-wide association and genomic selection analysis of the number of leaves above the ear in maize

Yang Xin-Yu, Cui Wen-Tao, Dilinigeer Alimu, Wang Kai-Xiang, Wu Peng-Hao, Ren Jiao-Jiao

Acta Agronomica Sinica. 2026, 52(5):  1573-1590.  doi:10.3724/SP.J.1006.2026.53065

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The number of leaves on the ear is an important trait influencing maize plant architecture. Genetic mapping approaches can identify single nucleotide polymorphisms (SNPs) significantly associated with this trait and facilitate the discovery of candidate genes, thereby laying a foundation for targeted breeding of ideal maize plant architecture and efficient enhancement of grain yield. In this study, a natural population of 291 maize inbred lines was evaluated across multiple environments. Genotyping was performed using sequencing technologies, and both genome-wide association studies (GWAS) and genomic selection (GS) were conducted for the leaf number above the ear (LNAE). LNAE was significantly affected by genotype (G), environment (E), and the genotype-by-environment interaction (G × E) (P < 0.001), with a broad-sense heritability of 81.23%. Using the MLMM model, 15 SNPs significantly associated with LNAE were identified, each explaining 1.12% to 22.43% of the phenotypic variation. The FarmCPU model identified 37 significant SNPs, with individual contributions ranging from 0.02% to 18.23%. A total of 11 co-located loci were detected on chromosomes 2, 4, 5, 6, 7, and 9 were detected by two different models. Among them, SNP 5_93495559 on chromosome 5 was identified as both an environmentally stable and model co-located locus. Compared with previous reports, this SNP represents a novel genetic locus. By integrating association mapping, co-location analysis, and candidate gene expression profiling, three genes—Zm00001eb315650, Zm00001eb315660, and Zm00001eb089980—were found to exhibit high expression during key leaf development stages and were identified as likely candidates underlying LNAE. Genomic selection analysis indicated that using 70% of the population as a training set and 3000 SNPs could achieve high prediction accuracy. This parameter can be utilized for molecular breeding selection of the number of leaves above the ear.