Physiological mechanisms of exogenous salicylic acid-mediated enhancement of salt tolerance in Davidia involucrata seedlings
In this study,we used the seedlings of rare and endangered species Davidia involucrata as mate-rials,and investigated the effects of the exogenously applied salicylic acid(SA)on the growth,photosyn-thetic pigment content,photosynthetic efficiency,carbohydrate content,and ion homeostasis in D.involu-crata seedlings under NaCl stress.Our data revealed that foliar spraying with 2 mmol·L-1 SA alleviated NaCl stress-induced photoinhibition,promoted the biomass accumulation and root activity,increased the contents of chlorophyll,carotenoid,fructose,glucose and sucrose as well as the net photosynthetic rate(Pn),stomatai conductance(Gs),transpiration rate(Tr),and decreased the senescence rate,intercellular CO2 concentration(Ci),and starch content.Moreover,SA application significantly decreased Na+content and increased K+content in the leaves of D.involucrata seedlings under NaCl stress.Correlation analysis indicated that the total chlorophyll content,Pn,and biomass accumulation had extremely significant nega-tive correlation with Na+and Na+/K+and extremely significant positive correlation with K+.Taken together,SA application enhanced salt tolerance of D.involucrata seedlings by promoting photosynthetic efficiency,increasing soluble sugar content,and maintaining ion balance.
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