4种常见双子叶植物蒸腾作用与叶温关系的研究

对4种常见双子叶植物的蒸腾速率日变化、蒸腾速率与气温以及叶温日变化的关系进行了研究．结果表明：（1）海棠的蒸腾速率日变化为单峰型曲线，夹竹桃的蒸腾速率日变化为双峰型曲线，月季和海桐花的蒸腾速率日变化均为无峰型曲线，一天当中始终处于下降的趋势．（2）4种植物午后蒸腾速率随气温的变化基本一致，都呈现出随气温下降而下降的趋势；但从8：00到14：00，4种植物的蒸腾速率的变化不同．（3）海棠有效的蒸腾作用使其叶温在大部分时间低于气温；夹竹桃的蒸腾“午降”，使其叶温在一天的大部分时间高于气温；月季和海桐花持续降低的蒸腾速率导致它们的叶温在大部分时间高于气温．

On the relationship between the transpiration rate and the leaf temperature of four dicotyledon plants

Four dicotyledon plants were selected to study their diurnal changes of transpiration rate, the relationship between the transpiration rate and both the air temperature and the diurnal changes of leaf temperature. The results were as follows： （1） the diurnal changes of transpiration rate of Malus spectabilis showed a single peak curve, The diurnal changes of transpiration rate of Nerium indicum displayed a double-peak curve. The diurnal changes of transpiration rate of the Rosa chinensis and the Pittosporum tobira didn＇t have the peak and their transpiration rate declined all day, （2）The declined changes of the tran- spiration rate of the four species in the afternoon were almost same as that of the air temperature. But there were difference among the four species from 8z00 to 14：00, （3）The effective transpiration of Malus spectabilis made the leaf temperature be lower than the air temperature in much daytime, The transpiration of the Nerium indicum declined at noon which made the leaf temperature higher than the air temperature in much daytime. The leaf temperature of the Rosa chinensis and the Pittosporum tobira were higher than the air temperature in much daytime because of the transpiration decreased steadily.