遮荫对濒危植物甜菜树光合生理和叶绿素荧光特性的影响

Effects of shading on the photosynthetic characteristics and chlorophyll fluorescence of the endangered plant Yunnanopilia longistaminata

以西南特有濒危植物甜菜树为材料,研究了不同遮荫处理(全光照、50%遮荫、65%遮荫和80%遮荫)对甜菜树叶片光合特性、叶绿素荧光和气孔特征的影响,为甜菜树种质资源保育和开发利用提供科学依据。结果表明:50%遮荫处理显著提高了甜菜树叶片净光合速率,80%遮荫处理则起抑制作用;50%遮荫和65%遮荫处理提高甜菜树叶蒸腾速率,有利于光合作用的进行;80%遮荫处理下胞间CO2浓度提高,抑制了甜菜树叶蒸腾作用和光合作用;50%遮荫和65%遮荫处理下净光合速率提高,说明甜菜树对遮荫有一定的适应性;叶绿素荧光方面,80%遮荫处理导致叶片PSⅡ最大光化学效率(Fv/Fm)和实际光化学效率(ФPSⅡ)下降。甜菜树叶片光合特性与气孔结构关系密切,遮荫降低甜菜树叶片气孔密度。

In order to provide the scientific basis for the species conservation and sustainable exploitation and utiliza-tion,the effect of different shadness（0,50%,65% and 80% shading）on the photosynthetic characteristics,chloro-phyll fluorescence and stomata structure of an endangered species Yunnanopilia longistaminata were studied.The results indicated that net photosynthetic increased at 50% shading but decreased at 80% shading.The transpiration rate and stomatal conductance increased at both 50% and 65% shading,which was helpful to photosynthetic process. Meanwhile,both of net photosynthetic and transpiration rates of the plant were suppressed as a result of the stomata limitation and the increase of the intercelluer CO2 at 80% shading.For the chlorophyll fluorescence parameters,the maximal photochemical efficiency （F v/F m ）and the actual quantum yield of photosystem Ⅱ（ΦPSⅡ）decreased signifi-cantly under 80% shading.Shading treatments also decreased the stomatal density and stomatal index.