非充分灌溉条件下作物根冠通讯与光合碳同化机理研究

Studying on the mechanism of root to shoot communication and photosynthetic carbon assimilation, is an important pathway to excavate biological water-saving potential and improve water use efficiency of crops. Nowadays, the root to shoot communication theory has been formed preliminarily. However, many problems in the research of root-sourced signal transmission and photosynthetic carbon assimilation, which was regulated by transmitted signal, are still not clear. Based on the previous work, the research of root to shoot communication and photosynthetic carbon assimilation mechanism under non-sufficient irrigation were designed with maize pot experiments. The objective of this study is to reveal the effective mechanisms of hydraulic signal and root-sourced chemical signals, and to discuss synergistic effect of xylem pH on root-sourced ABA, analyze the transport mechanism of root-sourced signal ABA and ACC and interaction between ABA and ethylene in coordinating stomatal behavior. This study also attempts to illuminate the effect of stomatal movement on PSII absorption, transmission, utilization and dissipation of excitation energy under non-sufficient irrigation, determine the major factor inhibiting of photosynthetic carbon assimilation under non-sufficient irrigation, and define the effect of water deficit on photosynthetic carbon assimilation and water use efficiency. This study can provide important basis for improving knowledge of root to shoot communication and photosynthetic carbon assimilation, exploiting crop root-sourced signalling system for irrigation technology development, and improving agricultural water use efficiency.

深入研究根冠通讯与光合碳同化机理，是挖掘作物自身生物节水潜力，提高水分利用效率的重要途径。目前虽然根冠通讯理论已经初步形成，但根源信号传输机制与传输信号调控下的光合碳同化研究中尚有许多问题仍不清楚。本研究在前期工作基础上，拟以玉米为供试作物，应用盆栽机理试验，对非充分灌溉条件下的根冠通讯与光合碳同化机理进行研究。旨在揭示水力信号与根源化学信号的作用机制；探讨木质部pH对根源信号ABA的协同效应；分析根源ABA与ACC的信号传输机制，及ABA与乙烯在气孔调控过程中的交互效应；阐明非充分灌溉条件下气孔运动对光系统Ⅱ反应中心激发能吸收、传递、利用与散失的影响，进一步判断非充分灌溉条件下限制光合碳同化的主要因素，明确水分亏缺对光合碳同化与水分利用效率的影响。这为完善根冠通讯与光合碳同化研究、利用作物根源信号系统发展灌溉技术、提高农业用水效率，提供了重要依据。

在前期工作基础上，本项目应用盆栽试验，对非充分灌溉条件下作物根冠通讯与光合碳同化机理进行了研究。结果表明：基于非充分灌溉的根源化学信号传输能够诱导气孔关闭并优化作物水分利用。同时，这些信号以根源ABA为核心、且相互之间存在拮抗或协同效应；其中，ABA能够促进气孔关闭，而CK则起到促进气孔开放的作用；因此，ABA/CK可以作为调控气孔运动的复合信号。此外，轻度水分亏缺条件下，气孔因素是限制光合碳同化的主要原因，且此时水分利用效率往往逐步升高；但随着亏水程度的加剧，非气孔因素逐渐成为限制光合的主要原因；重度水分亏缺条件下，水分利用效率亦会呈现出降低趋势。本项目取得的一系列研究结论为发展节水灌溉提供了理论基础与技术指导。