Abstract
The leaf temperature of terrestrial plants is influenced by such factors as not only the air temperature but the radiant heat from the sun and the vaporization heat by the transpiration. The leaf temperature of crassulascean acid metabolism (CAM) plants which make very little transpiration in daytime can be high. We measured leaf temperatures of CAM plant, Kalanchoe daigremontiana, and C3, Hybiscus cannabinus, in summer daytime. The leaf temperature of C3 plant was almost equal to the air; however that of CAM was 14.9oC higher than air. This results suggest that the leaf temperature of CAM plants rise to over 45oC at summer day. For discussing the influence on photosynthesis we measured photosynthetic rate in the phytotron. At 36oC, the induction time of photosynthesis was longer. At 40oC, the photosynthesis remarkably declined.
