【摘要】 选取桂林丫吉岩溶试验场优势植物黄荆(Vitex negundoL.)作为研究对象,对相同条件下黄荆叶片净光合速率(Pn)、气孔导度(Gs)、胞间二氧化碳浓度(C i)和蒸腾速率(Tr)等光合作用特性的日变化进行了比较研究。结果表明:净光合速率(Pn)的日变化呈不对称的"双峰型"曲线,具有明显的光合"午休"现象;气孔导度曲线总体呈下降趋势;胞间CO2浓度日变化表现出单峰曲线;蒸腾速率(Tr)日变化呈不对称的双峰曲线,与净光合速率日变化基本一致,但主峰较净光合速率Pn主峰滞后1 h,也出现了"午休"现象。更多还原

【Abstract】 Taking Vitex negundo as an object of study in Yaji Karst Proving Ground in Guilin.We studied Vitex negundo leaves in the diurnal variation of photosynthesis: net photosynthesis(Pn),stomatal conductance(Gs),intercellular CO2 concentration(Ci),and transpiration(Tr).The result shows that Pn can be described as an unsymmetrical dual-peaked curve with an obvious midday depression of the photosynthetic eficiency;the diurnal variation of intercellular CO2 concentration(Ci) presents single-peaked curves;the increase of Ci at midday indicates that the midday depression of the photosynthetic efficiency was mainly influenced by the non-stomatal limited elements;and the curve of(Tr) is unsymmetrical and dual-peaked which is consistent with Pn.In a word,great differences of diurnal variation of photosynthesis are observed from the leaves which belong to different ages and different places of the same Vitex negundo.更多还原