The main results are as following:1 For clear days, the diurnal variation of net photosynthetic rate (P_n) and transpiration rate (Tr) existed in H. brasiliensis are the two-peaked curve.

• 1 晴天，橡胶苗净光合速率(P_n)和蒸腾速率(T_r)日变化为双峰型曲线，有较明显的“午休”现象。