土壤水分含量对梨叶片光合特性的影响

以盆栽黄冠梨幼树为试材,研究不同土壤水分含量(SWC)对光合作用的影响规律,以确定梨园节水灌溉适宜的土壤水分调控指标.结果表明,SWC为50.6%时水分利用效率(WUE)最高;SWC由97.9%降至50.6%时,气孔导度(Gs)、蒸腾速率(Tr)与净光合速率(Pn)均下降,但Tr的下降幅度大于Pn的下降幅度而导致WUE的升高.SWC由50.6%降至19.7%时,WUE降低,降低的主要原因在于羧化效率下降导致Pn的大幅度降低.干旱复水后,Pn和Tr均有较大的回升,复水第2天后SWC为98.5%时,Pn和Tr大幅度的回升,但Tr回升的幅度更大,导致此时的WUE降为整个试验阶段的最低;复水第5天SWC为66.8%时,Pn和WUE均低于对照,这可能与叶片羧化功能受损后Pn不易恢复有关.

Responses of the Photosynthetic Characteristics of Pear Leaf to the Different Contents of Water in Soil

Huangguan,young pear tree planted in pot was studied under the different soil conditions in order to explore the effect of the water stress in soil on photosynthesis and the suitable soil water content(SWC) for water-saving irrigation in the pear orchard.The results showed that when SWC was 50.6 %,the water use efficiency(WUE) was the highest.SWC was from 97.9 % to 50.6 %,Pn,Tr and Gs were dropped,but WUE was higher.SWC was from 50.6 % to 19.7 %,WUE was dropped.Pn and Tr were increased after rewatering.SWC was 98.5 %,Tr was significantly increasd more than Pn,which resulted in WUE was the lowest among experimental period.SWC was 66.8 %,Pn and WUE were lower than CK.