间作优势的光合生理机制及其冠层微环境特征

Research progress on photo-physiological mechanisms and characteristics of canopy microenvironment in the formation of intercropping advantages

  • 摘要: 现代农业发展面临减排、化石物质减投、稳产高产等诸多挑战, 间作是一种能够同时保证产量与系统可持续性的生产方式, 是解决上述问题的重要途径。间作优势主要源于: 种间互作对时空的集约利用, 形成了利于作物生长和资源高效利用的根系结构、冠层结构, 创造了适宜的根际环境、冠层微环境, 优化了作物生长发育的生理指标。鉴于光合作用在产量形成中的决定性作用, 厘清间作优势形成的光合生理机制及其与冠层微环境的相关关系, 将对优化间作管理技术、进一步挖掘间作优势提供重要理论依据。本文综述了间作光合生理在群体水平—个体及器官水平—细胞及分子水平的研究进展: 间作有利于群体生育后期保持较高光合源, 优化干物质的积累、分配和转运; 提高了高位作物个体的光合速率、叶绿素含量、光能利用率, 但削弱了矮位作物光合性能; 在细胞及分子水平, 间作存在使高位作物Rubisco和PEPC酶活性提高, 而矮位作物光合关键酶活性下降的趋势, 以及间作存在使高位作物(玉米) pepcppdk光合酶基因表达上调且矮位作物(大豆)光反应中心相关编码基因同时上调的趋势。就间作冠层微环境而言, 间作高位作物冠层中下部受光增加, 温度变化幅度减小, 有利于其生长; 而间作矮位作物受到遮荫和光质恶化, 以及冠层温度降低、湿度增加的影响, 生长受抑。利于优化间作光合生理和冠层微环境调控的途径包括: 搭配高秆喜光作物及矮秆耐荫作物品种, 适度增加矮秆作物行比, 适量增施氮磷肥等。展望未来, 间作研究需用分子生物学手段解析间作微观尺度上的响应机制, 应用生长模型模拟作物生长规律和种间关系, 选育适于种间互作增效的专用品种, 统筹协调适宜机械化与种间互作增效的空间布局, 完善群体优化理论。

     

    Abstract: Intercropping is a production approach that can address the issues faced by modern agriculture, such as lowering green gas emissions and fossil material input, while also ensuring yields and system sustainability. The benefits of intercropping are primarily derived from the efficient use of time and space through interspecific interactions, formation of a root and canopy structure that is conducive to crop growth and resource efficiency, creation of an appropriate rhizosphere environment, and optimization of the physiological indicators of crop growth and development. Clarifying the photo-physiological mechanism of intercropping and its relationship with the canopy microenvironment will serve as crucial theoretical support for improving intercropping management technology and fully utilizing the advantages of intercropping. This study reviews the literatures on intercropping photosynthetic physiology at various levels, including populations, individuals, organs, cells, and molecules. Intercropping promotes the maintenance of photosynthetic sources and optimizes dry matter accumulation, distribution, and transportation at the population level; it increases the photosynthetic rate, chlorophyll content, and radiation use efficiency of tall crops but weakens the photosynthetic performance of short crops at the individual and organ levels. Additionally, the activities of phosphoenolpyruvate carboxykinase (PEPC) and Rubisco enzyme in tall crops are increased, whereas they are decreased in short crops; and intercropping tends to upregulate the expression of pepc and ppdk photosynthase genes in tall crops (maize) and upregulate genes encoding photoreaction centers in short crops (soybean). In terms of the intercropping canopy microenvironment, tall crops benefit from greater light interception and minimal temperature fluctuation. However, short crops experience deterioration in both light quantity and quality, lower canopy temperature, and higher humidity, which are unfavorable for crop growth. Regulatory approaches to promote the photo-physiology of intercropped crops and improve the canopy microenvironment include matching tall light-loving varieties and short shade-tolerant crop varieties, moderately increasing the row ratio of dwarf crops, and moderately increasing nitrogen and phosphorus fertilizers. Future research should explore the mechanisms at the microscale of intercropping using molecular biology techniques, discover growth laws and interspecies relationships of intercropping crops via growth model methods, breed special varieties to enhance interspecific interaction, and coordinate the spatial layout and group optimization theory appropriate for mechanization and interspecific interaction.

     

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