Study on Diurnal Variation of Photosynthetic Characteristics of Qiongzhuea tumidinoda
Wang Linhao1, Dong Wenyuan2, Tang Hailong3, Zhang Ying3, Gu Bao3
1 College of Environment Science and Engineering, Southwest Forestry University, Kunming 650224, Yunnan, China; 2 Research Institute of Biodiversity, Southwest Forestry University, Kunming 650224, Yunnan, China; 3 College of Forestry, Southwest Forestry University, Kunming 650224, Yunnan, China
Abstract：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.
