Journal of Integrative Agriculture ›› 2024, Vol. 23 ›› Issue (7): 2211-2226.DOI: 10.1016/j.jia.2023.07.006

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群体异质分布通过优化光环境提高小麦抗倒伏能力

  

  • 收稿日期:2023-04-03 接受日期:2023-06-09 出版日期:2024-07-20 发布日期:2024-07-01

Heterogeneous population distribution enhances resistance to wheat lodging by optimizing the light environment

Yibo Hu1, 2, Feng Qin1, 2, Zhen Wu1, 2, Xiaoqin Wang1, 2, Xiaolong Ren1, 2, Zhikuan Jia1, 2, Zhenlin Wang3, Xiaoguang Chen4#, Tie Cai1, 2#    

  1. 1 College of Agronomy, Northwest A&F University, Yangling 712100, China
    2 Key Laboratory of Crop Physi-Ecology and Tillage Science in Northwestern Loess Plateau, Ministry of Agriculture and Rural Affairs, Northwest A&F University, Yangling 712100, China
    3 College of Agronomy, Shandong Agricultural University/State Key Laboratory of Crop Biology, Tai’an 271018, China
    4 Xuzhou Institute of Agricultural Sciences in Jiangsu Xuhuai Area, Xuzhou 221131, China

  • Received:2023-04-03 Accepted:2023-06-09 Online:2024-07-20 Published:2024-07-01
  • About author:#Correspondence Tie Cai, E-mail: caitie@nwsuaf.edu.cn; Xiaoguang Chen, E-mail: chenxggw@163.com
  • Supported by:
    This work was funded by the National Natural Science Foundation of China (32071955) and the Natural Science Foundation of Shaanxi Province, China (2018JQ3061).  

摘要:

目前,倒伏仍是持续提升小麦产量的关键限制因素,因为在高产栽培的群体中,低光照胁迫会降低茎秆的机械强度。茎秆机械性能由节间木质素决定,其受群体光环境影响。能否通过群体分布改善光照条件抑制茎秆倒伏,迄今了解甚少。为此,本试验以小麦品种“西农979”为试验材料,设置低密度均质分布处理(LD)、高密度均质分布处理(HD)和高密度异质分布处理(HD-h),研究群体分布对小麦茎秆抗倒伏性能的调控效应与作用机制。结果显示,相比于LD处理,HD处理下冠层中下层透光率、植株中下部叶净光合速率、茎秆木质素积累量、茎秆抗折断力均显著降低,倒伏指数显著上升,而发生倒伏20202021年倒伏率为67.5%20212022年为59.3%HD-h处理下冠层中下层透光率等指标则较HD处理明显提高,而倒伏指数降低,且无倒伏现象。在茎秆形成的关键时期,与LD相比,HD条件下茎秆中PAL(苯丙氨酸转氨酶4CL(4-香豆酸:辅酶A连接酶COMT(咖啡酸3氧甲基转移酶CAD(肉桂醇脱氢酶)在木质素合成途径中的活性显著降低,TaPAL, Ta4CL, TaCOMT, 和TaCAD的相对表达量显著下调。然而,与HD相比,HD-h下木质素合成相关酶的活性及其基因表达量显著提高。进一步通过PLS路径分析显示,群体冠层光环境、植株中下部叶光合性能、木质素合成与积累、茎秆抗倒伏性能之间均为显著的正效应。结果表明,在传统高密度种植模式下,小麦倒伏风险增高。在此基础上,通过群体异质性分布调优冠层光环境,提高植株中下部叶光合性能,促进茎秆木质素积累,进而增强小麦抗倒伏性能。这些发现解释了小麦高产栽培条件下茎秆机械强度降低的机理,为小麦抗倒伏技术途径提供思路与理论依据。

Abstract:

Lodging is still the key factor that limits continuous increases in wheat yields today, because the mechanical strength of culms is reduced due to low-light stress in populations under high-yield cultivation.  The mechanical properties of the culm are mainly determined by lignin, which is affected by the light environment.  However, little is known about whether the light environment can be sufficiently improved by changing the population distribution to inhibit culm lodging.  Therefore, in this study, we used the wheat cultivar “Xinong 979” to establish a low-density homogeneous distribution treatment (LD), high-density homogeneous distribution treatment (HD), and high-density heterogeneous distribution treatment (HD-h) to study the regulatory effects and mechanism responsible for differences in the lodging resistance of wheat culms under different population distributions.  Compared with LD, HD significantly reduced the light transmittance in the middle and basal layers of the canopy, the net photosynthetic rate in the middle and lower leaves of plants, the accumulation of lignin in the culm, and the breaking resistance of the culm, and thus the lodging index values increased significantly, with lodging rates of 67.5% in 2020–2021 and 59.3% in 2021–2022.  Under HD-h, the light transmittance and other indicators in the middle and basal canopy layers were significantly higher than those under HD, and the lodging index decreased to the point that no lodging occurred.  Compared with LD, the activities of phenylalanine ammonia-Lyase (PAL), 4-coumarate: coenzyme A ligase (4CL), catechol-O-methyltransferase (COMT), and cinnamyl-alcohol dehydrogenase (CAD) in the lignin synthesis pathway were significantly reduced in the culms under HD during the critical period for culm formation, and the relative expression levels of TaPAL, Ta4CL, TaCOMT, and TaCAD were significantly downregulated.  However, the activities of lignin synthesis-related enzymes and their gene expression levels were significantly increased under HD-h compared with HD.  A partial least squares path modeling analysis found significant positive effects between the canopy light environment, the photosynthetic capacity of the middle and lower leaves of plants, lignin synthesis and accumulation, and lodging resistance in the culms.  Thus, under conventional high-density planting, the risk of wheat lodging was significantly higher.  Accordingly, the canopy light environment can be optimized by changing the heterogeneity of the population distribution to improve the photosynthetic capacity of the middle and lower leaves of plants, promote lignin accumulation in the culm, and enhance lodging resistance in wheat.  These findings provide a basis for understanding the mechanism responsible for the lower mechanical strength of the culm under high-yield wheat cultivation, and a theoretical basis and for developing technical measures to enhance lodging resistance.


Key words: canopy light environment , lignin ,  lodging ,  population distribution ,  wheat