Responses of Photosynthetic Physiological Characteristics of Mulberry Leaf to Soil Moisture and Light Intensity

In present study,we measured net photosynthetic rate(Pn),transpiration rate(Tr),water use efficiency(WUE) and light use efficiency(LUE) of two-year-old mulberry leaves under different soil water conditions by using CIRAS-2 portable photosynthesis system.The response pattern of photosynthetic physiological parameters of mulberry leaf to soil moisture and light intensity was analyzed to provide theoretical basis for developing mulberry cultivation technology with characteristics of water saving and high yield.The results showed that with the decreasing of relative soil water content(from 94.3% to 28.7%),Pn,apparent quantum yield(Φ) and LUE increased first and then declined,while dark respiration rate(Rd) and light compensation point(LCP) decreased first and then increased,and Tr and light saturation point(LSP) decreased all the time.The above results suggest that photosynthetic physiological parameters of mulberry leaves had threshold response to the change of soil moisture and light intensity.Higher net photosynthetic rate and water use efficiency were observed under the conditions of relative soil water contents from 44.8% to 77.8%(the optimum relative soil water contents were around 52.0%) and photosynthetic active radiation from 800 to 2 000 μmol/(m2·s).