木荷夏季气体交换、光能和水分利用效率的日变化

Diurnal Variation of Gas Exchange,Solarenergy Use Efficiency and Water Use Efficiency of Schima superba Leaves in Summer

木荷叶片净光合速率日进程曲线为“双峰”型,光合效率午间明显降低,主要由非气孔限制引起.蒸腾速率的日变化为“单峰型”,午间最高.光能利用效率和水分利用效率早晚较高,午间较低.利用多元逐步回归方法分别得到了净光合速率、蒸腾速率、气孔阻力、光能利用效率和水分利用效率与环境因子的最优方程.

The diurnal variations of net photosynthetic rate （Pn）, transpiration rate （Tr）, stomatal resistance （rs）, solarenergy use efficiency （SUE） and water use efficiency （WUE） of Schima superba leaves under natural conditions had been studied. The results were as follows ： in summer clear days, the curves of diurnal variations of Pn had two peaks, and Pn obviously declined at midday which was caused by nonstomatal limited elements. Tr had single peak which showed the maximum at noon. SUE and WUE were higher in the morning and evening, and were lower at noon. The most excellent equation of the diurnal variation of Pn, Tr, rs, SUE and WUE were attained by the methods of stepwise multi-regression, respectively.