UV-B辐射增强影响芒果成年树栽培表现和光合作用的生理生化机制研究

Reductions of ozone layer have led to a substantial increase in UV-B radiation on the surface of earth. The intensive UV radiation in the tropical region can influence the photosynthesis of the tropical fruit trees and their field performances. In this study, Some mango adult trees will firstly be treated with various doses of enhanced UV-B radiation, and then the growth and yield changes of the trees,as well as the metabolites of reactive oxygen species in leaves and fruits will be detected, at the same time, the mangiferin accumulation in leaves and fruits after UV-B radiation as well as its effects on the metabolism of reactive oxygen species will be analyzed too. From the experiments,the ranges of the UV-B radiation of improving and inhibitting the growth and development of mango trees will be determined.The other mango adult trees then will be treated accordingly, and the differences in the field performances, the microstructures and the ultrastructures of leaves, the content of magiferin in leaves, and the physiological and biochemical parameters related to photosynthesis will be compared in different treatments, from these data, the effects of mangiferin on the responses of mango trees photosynthesis to the enhanced UV-B radiation will be understood, and the physiological and biochemical responses of mango trees photosynthesis to the UV-B radiation will be determined.The physiological and biochemical mechanisms of UV-B radiation on the growth and development of mango fruits will be formulated. The results of this study will improve the theories of fruit tree's photosynthesis and the resistence in light stress, and provide the theoretical basis to improve the adaptability of mango trees to the enhanced UV-B radiation.

大气臭氧层变薄导致到达地面的UV-B辐射增强，热带地区紫外辐射强烈，UV-B辐射增强会影响芒果的栽培表现和光合作用。通过人工模拟不同强度梯度的UV-B辐射增强处理芒果成年树，观测树体栽培表现、叶片和果实活性氧代谢变化，探讨芒果苷积累与UV-B辐射增强强度变化的关系及其在活性氧代谢中的作用，从而确定促进和抑制芒果生长发育的UV-B辐射增强强度范围。再通过合理的低和高强度的UV-B辐射增强处理芒果成年树，调查栽培表现差异，观察叶片显微和超微结构改变，检测叶片光合作用一系列重要生理生化指标和芒果苷含量的变化，探讨芒果苷在芒果光合作用对UV-B辐射增强响应中的作用，确定UV-B辐射增强影响芒果光合作用的特征，总结出低和高强度UV-B辐射增强分别促进和抑制芒果果实生长发育和叶片光合作用的生理生化机制。本研究可发展果树光合作用和抗光照逆境生理理论，指导制定芒果适应UV-B辐射增强环境的合理栽培技术。

大气臭氧层变薄导致到达地面的UV-B辐射增强（即增强UV-B辐射），热带地区紫外辐射强烈，增强UV-B辐射会影响芒果的栽培表现和光合作用。通过人工模拟不同剂量梯度的增强UV-B辐射分别处理台农一号芒果和金煌芒果，观测树体栽培表现、叶片和果实活性氧代谢变化，确定UV-B辐射增强促进和抑制芒果成年树生长发育的辐射强度范围；再人工模拟低和高剂量的增强UV-B辐射处理芒果成年树，研究UV-B辐射增强影响芒果成年树栽培表现和光合作用的生理生化机制。48kJ•m-2•d-1的增强UV-B辐射处理可引起叶片和果实损伤，高剂量增强UV-B辐射可引起减产和果实营养、风味品质变劣，导致Pn、Gs和Tr下降；叶片芒果苷和果皮未知呫吨酮类化合物等含量升高，同时通过增强叶片、果皮和果肉抗氧化酶活性和提高其它还原性、吸收UV-B辐射等成分含量，尽可能减轻活性氧损伤；树体损伤和抗氧化保护等均表现出剂量效应和积累效应；未见低剂量增强UV-B辐射促进树体和果实的生长和发育。高剂量处理后，栅栏组织细胞变小，海绵组织细胞出现细胞变大，两种组织细胞混杂；海绵组织细胞间隙增大而更疏松；叶片角质层变厚；上述结构变化对低剂量处理而言则与CK无显著差异。增强UV-B辐射处理均促进光化学荧光猝灭系数、希尔反应活力、RuBP羧化酶活性和PEP羧化酶活性的提高，高剂量处理的促进作用更显著；高剂量处理的胞间CO2浓度最低；高剂量处理呈抑制RuBP羧化酶基因表达的趋势；说明抑制Pn主要是气孔限制。这表明可以通过制定合理的栽培技术来刺激抗氧化酶系活性增强、抗氧化成分和能吸收 UV-B 辐射的成分积累增加，补充 Vc，进而提高芒果树抗或耐增强 UV-B 辐射的能力；芒果苷等呫吨酮类化合物是人类重要的目前尚不能化工合成的天然产物，增强UV-B辐射处理树体后，可能提升了叶片和果皮开发为医药、兽药、饲料、化妆品和保健品等加工价值。