南亚热带丘陵区龙眼和象草的叶片气孔气体交换的研究

分别在干、湿两季节 ,利用便携式光合测定系统 ,野外测定丘陵集水区“林、果、草、鱼”农林复合生态系统中龙眼和象草的气体交换的日变化 ,和在室内测定 2种植物的光合作用—光响应曲线。2种植物在湿润高温的 9月的光饱和点、日平均叶片净光合速率、日平均气孔导度比干旱低温的 1月高 ,而内在水分利用效率恰好相反。2种植物的净光合速率的日变化呈双峰型 ,龙眼在 1月份中午时分下陷的程度相对较浅。根据观测结果 ,集水区内的水热条件的配合得当 ,是龙眼和象草生长的重要条件。

Stomatal gas exchange in leaves of Dimocarpus longan and Pennisetum purpureum in southern subtropical hilly I and

During dry and wet seasons respectively, measurements on daily gas exchange in leaves of Pennisetum purpureum and Dimocarpus longan of an agroforestry ecosystem "forest-fruit-grass-fish" on hilly land catchment were made with portable photosynthesis system. Indoor examinations on photosynthesis-light response curve of both plants were also undertaken. The light-saturated point, mean daily net photosynthetic rate and stomatal conductance of both plants were higher in September characterized with wet and high temperature condition than in dry and low temperature January. Their intrinsic water use efficiencies, however, were in reverse situation. The daily change of their net photosynthetic rates displayed two-peak pattern. But the midday depression of net photosyntlhetic rate of Dimocarpus longan in January was not so obvious. It was, based on the measurements, suggested that appropriate coordination of water and heat in the catchment be important for their growth