Leaf senescence and source-sink dynamics in soybean: Insights from maize-soybean intercropping systems

IF 6.4 1区农林科学 Q1 AGRONOMY

Field Crops Research Pub Date : 2025-09-09 DOI:10.1016/j.fcr.2025.110130

Zhen Fan , Binbin Qiang , Yanrong Lin , Pengzhao Liu , Zhipeng Li , Mengwei Cheng , Xining Zhao , Xiaolong Ren , Xiaoli Chen

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引用次数: 0

Abstract

Context

Leaf senescence and source-sink dynamics are critical determinants of crop productivity. In maize-soybean intercropping systems, divergent ecological niches create asymmetric resource competition between species. However, whether interspecific competition affects soybean yield formation by altering leaf senescence dynamics remains unclear.

Objectives

To investigate the leaf senescence process and source-sink balance patterns in different canopy layers (upper, middle, and lower leaves) and planting strips (border and inner row) of intercropped soybeans, elucidate the regulatory mechanisms linking leaf senescence dynamics to yield formation in maize-soybean relay intercropping systems.

Methods

A three-year experiment was conducted from 2021 to 2023 in Yangling District, Shaanxi Province, involving three treatments: sole maize (SM), sole soybean (SS), and maize-soybean intercropping (IC).

Results

Intercropping increased crop yield and land equivalent ratio (LER), with LER values ranging from 1.02 to 1.22. Across the three growing seasons, intercropped soybean (IS) yields exhibited interannual variability: reductions in 2022 (-17.5 %), marginal differences in 2021 (-4.4 %), and enhancements in 2023 (9.2 %) relative to sole soybean (SS). Before the beginning of the podding stage (R3), intercropped soybean faced significant shading from the adjacent maize. As the maize growing season progressed, intercropped soybean, particularly those in the border rows, received more photosynthetically active radiation (PAR) than sole soybean. Compared to sole cropping, intercropping significantly delayed the senescence of middle (by 2.85 days) and lower (by 4.84 days) canopy leaves in soybean, while the effect on upper leaves varied by year. In the later growth stages, the leaf area index (2.5 %–24.4 %), net photosynthetic rate (6.5 %–21.3 %), and chlorophyll content (11.4 %–29.7 %) of middle canopy leaves in intercropped soybean were significantly higher than those of sole soybean. In 2021 and 2023, intercropping delayed the time at which soybeans reached their maximum dry matter weight, which increased by 8.7 % and 11.5 % compared to sole cropping, respectively. Furthermore, the maximum grain filling rate of soybeans in the border rows increased by 8.8 % and 22.9 % compared to sole cropping.

Conclusions

The enhancement of light and water conditions during the later growth stages of soybean delayed leaf senescence and promoted the accumulation of photosynthetic assimilates after R3 stage. In wet years, intercropped soybean enhanced source growth and grain filling, optimized the source-sink relationship, and increased the yield of intercropped soybeans. In dry years, intercropped soybean faced source limitations, leading to a reduction in yield.

Implication

Our study elucidates the regulatory mechanisms of leaf senescence and source-sink relationship on soybean yield in intercropping systems, providing new insights into the yield-increasing physiological mechanisms of maize-soybean intercropping.

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大豆叶片衰老和源库动态：来自玉米-大豆间作系统的见解

叶片衰老和源库动态是作物生产力的关键决定因素。在玉米-大豆间作系统中，不同的生态位造成了物种间不对称的资源竞争。然而，种间竞争是否通过改变叶片衰老动力学影响大豆产量形成尚不清楚。目的研究间作大豆不同冠层（上、中、下叶）和种植带（边行和内行）叶片衰老过程和源库平衡模式，阐明玉米-大豆接力间作系统中叶片衰老动态与产量形成的调控机制。方法于2021 ~ 2023年在陕西省杨陵区进行为期3年的试验，分为单玉米（SM）、单大豆（SS）和玉米-大豆间作（IC） 3个处理。结果间作提高了作物产量和土地等效比（LER），其值在1.02 ~ 1.22之间。在三个生长季节中，间作大豆（IS）的产量表现出年际变化：与单作大豆（SS）相比，2022年减产（-17.5 %），2021年边际差异（-4.4 %），2023年增产（9.2 %）。在结荚期开始之前（R3），间作大豆面临来自相邻玉米的显著遮光。随着玉米生长季节的推进，间作大豆，特别是缘行间作大豆的光合有效辐射（PAR）高于单作大豆。与单作相比，间作显著延缓了大豆中部和下部冠层叶片的衰老（分别延缓了2.85天和4.84天），而对上部叶片的影响则因年份而异。在生育后期，间作大豆中冠层叶片的叶面积指数（2.5 % ~ 24.4 %）、净光合速率（6.5 % ~ 21.3 %）和叶绿素含量（11.4 % ~ 29.7 %）显著高于单作大豆。2021年和2023年，套作推迟了大豆达到最大干物质重的时间，比单作分别提高了8.7% %和11. %。与单作相比，边行大豆籽粒最大灌浆率分别提高了8. %和22.9 %。结论大豆生长后期光照和水分条件的改善延缓了叶片衰老，促进了R3期后光合同化物的积累。丰水年间作大豆促进了源生长和籽粒灌浆，优化了源库关系，提高了间作大豆的产量。在干旱年份，间作大豆面临来源限制，导致产量下降。意义本研究阐明了间作系统中叶片衰老的调控机制和源库关系对大豆产量的影响，为玉米-大豆间作增产的生理机制提供了新的认识。

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来源期刊

Field Crops Research 农林科学-农艺学

CiteScore

9.60

自引率

12.10%

发文量

307

审稿时长

46 days

期刊介绍： Field Crops Research is an international journal publishing scientific articles on: √ experimental and modelling research at field, farm and landscape levels on temperate and tropical crops and cropping systems, with a focus on crop ecology and physiology, agronomy, and plant genetics and breeding.