筇竹光合日变化特征研究

对筇竹春季、夏季和秋季的光合日变化特征进行了研究。结果表明:筇竹春季净光合速率日变化为单峰曲线,没有光合"午休"现象;夏季和秋季净光合速率日变化为双峰曲线,有明显的光合"午休"现象;筇竹光合"午休"现象的主要原因是非气孔因素所致;夏季的净光合速率最高,光合能力最强,是筇竹枝叶生长旺季。影响筇竹不同季节净光合速率的最稳定环境因子为光合有效辐射和大气温度。筇竹夏季和秋季蒸腾速率变化趋势均表现为双峰曲线,春季为单峰曲线;夏季和秋季均有蒸腾"午休"现象,春季则没有。光合有效辐射、大气温度和气孔导度是影响筇竹不同季节蒸腾速率的最稳定因子。

Study on Diurnal Variation of Photosynthetic Characteristics of Qiongzhuea tumidinoda

We studied the diurnal variation of photosynthetic characteristics of Qiongzhuea tumidinoda in spring, summer and autumn. The results showed that the net photosynthetic rate in spring was showed as the "single peak" curve with no "midday depression" phenomenon while the rate in autumn and summer was showed as "double peak" curves with obvious "midday depression" phenomenon. Non-stomatal factor was the main cause of "midday depression" phenomenon. The net photosynthetic rate and the photosynthesis ability were the strongest in summer, in which Q. tumidity grows vibrantly. Photosynthetically active radiation (PAR) and air temperature (T) are the most stable environmental factors affecting net photosynthetic rate in different seasons. The transpiration rates (Tr) of Q. tumidity in summer and autumn all showed the double peak curve, but single peak curve in spring; transpiration "lunch break" phenomenon appeared in summer and spring but not in spring. PAR, and stomatal conductance (Gs) are the most stable factors to transpiration rate in different seasons.