Light response characteristics of photosynthesis in three Juglans regia cultivars

In order to study physiological mechanism of light energy utilization differences among different cultivars,and to provide a theory base for high quality and efficient cultivation of different Juglans regia cultivars,taking ‘Luguang',‘Zha 343' and ‘Qiangtele' as materials,light response characteristics of photosynthesis were studied by using Li-6400 portable photosynthesis system.The results show that there are differences among parameters of light response curves of three cultivars.The maximum net photosynthetic rate(Amax),dark respiration rate(Rd),light saturation point and light compensation point of ‘Qiangtele' are higher than those indexes of ‘Luguang' and ‘Zha 343',and the apparent quantum yield(AQY) of ‘Luguang' is the highest.The responses of net photosynthetic rate(Pn),intercellular CO2 concentration(Ci),stomatal conductance(Gs),transpiration rate(Tr),vapor pressure deficit at leaf surface(Vpdl),leaf temperature(Tleaf) and water use efficiency(WUE) of the three cultivars have some differences to the photosynthetic available radiation(PAR).‘Qiangtele' is suited for general cultivation density under high-intensity light,and ‘Luguang' and ‘Zha 343' are suited for close cultivation and modest close cultivation under weak light condition,respectively.