七子花苗期光合生理生态特性研究

Study on the Characteristics of Photosynthetic Physio-ecology in Leaves of Heptacodium miconioides Seedlings

对七子花苗期的光合生理生态特性进行了研究 ,结果表明 :(1)净光合速率、蒸腾速率的日进程曲线呈“双峰”型 ,胞间 CO2 浓度的日进程基本与净光合速率相反 ,中午胞间 CO2 浓度增高表明净光合速率午间降低主要受非气孔限制因素的影响。暗呼吸速率日进程呈单峰曲线 ,中午最高。气孔阻力的变化规律与蒸腾速率基本相反。光能利用效率以上午 7:0 0为最高 ,中午最低 ,以后又逐渐上升。水分利用效率以 7:0 0最高 ,10 :0 0～ 16 :0 0较低。 (2 )一天分时段光响应试验表明 ,饱和光强和表观量子产额上午最高 ,中午最低 ,下午有所上升。上午和下午光补偿点比较接近 ,中午增高一倍多。不同时段遮光都使得蒸腾速率下降 ,以下午下降幅度最大 ,但使气孔阻力升高 ,下午增加幅度最大。 (3)上午羧化效率最高 ,中午最低 ,下午稍有上升 ,而 CO2

The characteristics of photosynthetic physio ecology in leaves of Heptacodium miconioides seedlings had been studied. The results showed as follows: (1) The diurnal variations of net photosynthetic rates (Pn) and transpiration rates (E) were 'twin peaked' curve. The diurnal variations of internal CO 2 concentration (C i) were just opposite to Pn. The increasing of C i at midday showed that the decreasing of Pn were related to non stomatal restriction factors. Respiration rates (R) were highest at midday, whose diurnal variations were 'single peaked' curve. The diurnal variations of stomatal resistance (r s) were just opposite to E. Solarenergy utilization efficiency (SUE) increased gradually in the afternoon, which was highest at 7∶00 in the morning and lowest at midday. Water utilization efficiency (WUE) was highest at 7∶00 and lower during 10∶00~16∶00. (2) The experiments of response of Pn to light indicated that saturated light intensity and apparent quantum yield (AQY) were highest in morning and lowest at midday. Light compensation points (LCP) were nearly in the morning and in the afternoon, but whose increasing had more than doubled at midday. E decreased under shad at different time, the most decrea sing of E were in the afternoon, on the contrary, r s increased at the same time. (3) Carboxylation efficiency (CE) were highest in the morning and lowest at midday, while CO 2 compensation points (CCP) were highest at midday.