The Physiological And Biochemical Effects Of Exogenous Spermidine To Blueberry Under Drought Stress

Blueberry is a kind of economic crops,which contains a variety of nutrients.Blueberry belongs to the shallow root system plant,which has a thin and not developed root hair,and it highly susceptible to the influence of drought condition.Spermidine is a kind of exogenous hormone,have a strong physiological activity in plants.Many studies indicated that the application of exogenous PA enhanced plant tolerance under abiotic stress.Many studies on biological,physiological and biochemical,and molecular biological characteristics of blueberry have been carried out,but little is known about the effects of exogenous SPD on the biochemical and physiological process of blueberry under drought stress.In this study we investigated the effects of exogenous SPD on plant growth,net photosynthetic rate(Pn),antioxidant enzyme activities,chlorophyll,malondialdehyde(MDA)and phytohormone contents in leaves of blueberry(Vaccinium corymbosun ‘Misty’)seedlings under drought stress.The results show that:1.Under drought stress: Drought stress severely reduced the relative water content(RWC),Chlorophyll,Pn,leaf nitrogen content,specific leaf weight(SLW),Indole-3-acetic acid(IAA),Gibberellic acid(GA)and Polyamine(PA)contents,while increased relative electrolyte conductivity(REC),MDA,total soluble sugar and Abscisic acid(ABA)contents,the activities of POD,SOD and CAT.2.Compared with seedlings without SPD treatment,SPD keep the leaf in a better form,increased the RWC.After the SPD treatment,REC,MDA,total soluble sugar and ABA contents in seedlings were decreased.Increased in chlorophyll,Pn,SLW,SOD,POD and CAT activities.These results signified the role of SPD in alleviating the negative effects of drought stress on plants and suggested that SPD could be used as a potential growth regulator,for improving plant growth under drought stress.