橡胶林下益智对降雨格局变化的响应机制研究

Alpinia oxyphylla is an important medical plant in South China, which planted the rubber tree. The rubber-alpinia oxyphylla intercropping model is the most important agroforestry model in the rubber plantation. Based on the previous research of our groups, the rainfall deficiency are significant factors that limiting growth and photosynthesis of alpinia oxyphylla. Nevertheless, little is known about the impact of precipitation pattern changes on alpinia oxyphylla. In this study, by the simulation of rainfall control test under the rubber-alpinia oxyphylla intercropping model, We analyze how xanthophyll cycle-mediated thermal dissipation, photorespiration and the water–water cycle pathways help to remove excess excitation energy from the photosynthetic electron transport chain by measuring of the gas exchange, fluorescence parameters, and estimating photosynthetic electron allocation. Then, the Synergistic responses was investigated from different Photoprotective Pathways in alpinia oxyphylla to drought. The compared with the changes in a series of enzymatic activity and non-enzymatic antioxidants content was reveal to production and detoxifying balancing mechanism of reactive oxygen species(ROS). The third part continues to analyze the levels of components and the activities of important enzymes in C and N metabolism, and to understand how different organs regulate the coordination of C and N metabolism that protected the cell components from the potential damage by ROS and osmotic stress. This series of studies provide certain theory support for water management of alpinia oxyphylla.

益智是我国四大南药之一，其间作在橡胶林下成为胶园最重要的农林复合模式。项目组前期研究发现，旱季降雨不足是橡胶林下益智生长和光合的主要限制因子。然而，旱季降雨变化下益智应对水分胁迫的响应机制尚不清楚。本项目从光保护途径和物质代谢调控的角度开展益智对降雨变化的应答机制研究，以益智为研究材料，在橡胶-益智模式下开展模拟降雨控制实验，测定益智气体交换、叶绿素荧光参数、并采用气体交换和荧光同步测量估算光合电子流分配，分析光合激发能在叶黄素循环、光呼吸、水-水循环的分配策略，揭示多种光保护途径的协同机制；比较在不同水分胁迫下抗氧化酶活性和抗氧化剂含量的差异，阐明益智细胞内活性氧防御系统的响应机制；测定根和叶的碳/氮代谢物含量和代谢酶活性，明确在维持细胞渗透平衡和避免膜脂过氧化进程中，益智不同器官协同调控碳、氮代谢酶活性和代谢物合成和积累的协同驱动效应。此研究为橡胶林下益智水分的科学管理提供理论依据。

益智是我国四大南药之一，其间作在橡胶林下成为胶园最重要的农林复合模式。项目组前期研究发现，旱季降雨不足是橡胶林下益智生长和光合的主要限制因子。然而，旱季降雨变化下益智应对水分胁迫的响应机制尚不清楚。本项目从光保护途径和物质代谢调控的角度开展益智对降雨变化的应答机制研究，以益智为研究材料，在橡胶-益智模式下开展模拟降雨控制实验，测定了益智气体交换、叶绿素荧光参数、并采用气体交换和荧光同步测量估算光合电子流分配，分析了光合激发能在叶黄素循环、光呼吸、水-水循环的分配策略。主要结果包括：（1）降水减少降低了土壤中的相对含水量并导致CO2的同化减少，进一步诱导过量活性氧积累，导致大量过剩激发能量和光合器官的损伤。延长的降水间隔加速了这些现象。（2）同时，热能耗散（由叶黄素循环介导）和水-水循环被激发，并参与了降水模式变化的整个响应过程，如耗散过剩的激发能、清除活性氧、保护光合作用膜（尤其是在 W处理中）。（3）由于关键酶的平衡调节，非结构碳水化合物(可溶性糖和淀粉)含量在降雨减少时增加，以调节叶片细胞水势应对逆境胁迫；同时，干旱胁迫加速了益智叶片的N代谢，减轻了NH4+对益智叶片细胞的毒害，增强了细胞的渗透调节。综上所述，益智光合器官生理策略将保证益智植株适应旱季降雨格局的变化，实现正常生长和光合作用。