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

The diurnal variations of net photosynthetic rate(P_n),transpiration rate(T_r),stomatal resistance(r_s),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 P_n had two peaks,and P_n obviously declined at midday which was caused by non-stomatal limited elements.T_r 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 P_n,T_r,r_s,SUE and WUE were attained by the methods of stepwise multi-regression,respectively.