Abstract：We measured the light response of photosynthetic physiology parameters by CIRAS-2 portable photosynthesis system, such as net photosynthetic rate, transpiration rate, water use efficiency and stomatal conductance, in two-year-old Diospyros Kaki under different soil water conditions. The light response rule of Diospyros Kaki was studied under series of soil moisture. The results show that soil water content had significant effects on the photosynthetic parameters of Diospyros Kaki. With the decreasing soil moisture, net photosynthetic rate and apparent quantum yield increased first, and then decreased. Meanwhile light compensation point decreased first, and then increased. Light saturation point represented a decreasing tendency. Higher net photosynthetic rate and water use efficiency were observed when the relative soil water contents (Rwc) were from 48.8% to 76.7% and the photosynthetic active radiation were from 800 to 2000μmol/(m2·s). Diospyros Kaki had the higher ability to utilize strong light, but lower to utilize weak light. When Rwc was 48.8%, the main reason of photosynthesis declination was stomatal limitation. As Rwc was 25.5%, the declination was changed from stomatal limitation turned to non-stomatal limitation. Judging from stomatal factor and non stomatal factor, we can get the conclusion that the drought resistance of Diospyros Kaki is very strong. The results in this study could provide theory for water saving activity and high yield cultivation of Diospyros Kaki.
2012, Vol. 10 
