西南喀斯特地区四种造林树种光合作用日变化及生态适应性研究

Research on Diurnal Variations of Photosynthesis and Adaptability of Four Sylvicultural Trees in Karst Area,Southwest China

以西南喀斯特地区4种造林树种茶条木（Delavaya toxocarpa）、樟叶槭（Acer albopurpurascens）、狗骨木（Cornus wilsoniana）、无患子（Sapindu smukorossi）为研究对象,分12个月每月于自然条件下利用Li-6400便携式光合测定系统测定了植物叶片气孔气体交换的相关特征和环境因子的日变化,以分析树种的生态适应性。结果表明：4种植物的净光合速率（Pn）、气孔导度（Gs）、蒸腾速率（Tr）日变化趋势均呈＂双峰＂曲线,中午出现光合＂午休＂均为非气孔因素限制,12：00~15：00光合速率降低则主要受气孔因素限制;水分利用效率（WUE）总体上呈递减趋势,傍晚CO2升高在一定程度上促进了水分利用效率的提高;对Pn影响最为显著的生态生理因子为Par、Gs,其次为Ci、Rh、Ta;茶条木、狗骨木Pn、WUE均相对较高,4种植物的初步适应性评价为：茶条木〉狗骨木〉樟叶槭〉无患子。

Delavaya toxocarpa,Acer albopurpurascens,Cornus wilsoniana and Sapindus smukorossi being sylvicultural trees in karst area in Southwest China,were chosen for the study on diurnal variation of stomatal gas exchange and environmental factors by the Li-6400 portable photosynthesis system.Measurements demonstrated that the diurnal curves of net photosynthetic rate（Pn）,stomatal conductance（Gs）,and transpiration rate（Tr） of all the four trees had two peaks and indicated evident of midday-depression,non-stomatal limitation may likely be a course of the midday decline of the photosynthetic efficiency,while the decline of the photosynthetic efficiency at 12：00 to 15：00 may be attributed to stomatal limitation.The water use efficiency（WUE） was in a descending status as a whole,and CO2 increase in the evening to some extent,contributed to the improvement of water use efficiency.The eco-physiological factors with the greatest effects on Pn was Par and Gs,followed by Ci、Rh and Ta.The values of Pn and WUE of D.toxocarpa and C.wilsoniana were relatively larger,In conclusion,the primary adaptation evaluation of the four trees in the order of D.toxocarpa,C.wilsoniana,A.albopurpurascens,and S.smukorossi.