The Effects Of Salicylic Acid On Physiological And Biochemical Characteristics Of Strawberry Leaves Under Water Stress

The paper attempts to study the effects of three different levels (mild, moderateand severe) of water stress and salicylic acid on osmoregulation substance, membranelipid peroxidation, activities of protective enzymes and drought-induced protein inleaves of strawberry by the method of pot experiment and artificial drought stress. Theresults are as follows: Strawberry seedlings were treated separately with threedifferent levels (mild, moderate and severe) of water stress. The content ofosmoregulation substance (soluble sugar, soluble protein, free proline) and MDA instrawberry leaves increased with the increase of degree and time of water stress. Theactivities of protective enzymes (SOD, POD, CAT) were increased first and thendecreased. On the sixth day after water stress,24.6KDa protein increased undermoderate water stress. On the eighth day,21.0KDa,24.6KDa increased under waterstress of three levels. On the tenth day,24.6KDa increased under moderate waterstress and21.0KDa,22.4KDa,103.5KDa increased under moderate and severe stress.Under moderate water stress, new polypeptides with molecular weights ofapproximate65.8KDa induced from leaves on SDS-PAGE gel on the eighth and tenthday. On the tenth day, new polypeptides with molecular weights of approximate28.7KDa induced from leaves under moderate and severe stress. In summary, thedamage of water stress on strawberry plants was related to the water deficit levels andstress time.Under water stress, the content of osmoregulation substance and MDA increasedin strawberry leaves treated with three different concentrations (0.1,1,10mmol/L) ofexogenous SA compared with the leaves which treated nothing. At the same time, thecontent of MDA reduced and the activities of SOD, POD and CAT increased bysprayed the appropriate concentration of SA. On the sixth day,28.4KDa,84.3KDaincreased in strawberry leaves sprayed with three different concentrations ofexogenous SA under water stress. On the eighth day,24.1KDa,84.3KDa,101.3KDaincreased in leaves sprayed with exogenous SA and new polypeptides with molecularweights of approximate100.1KDa induced in stress treatments. Under water stress,new polypeptides with molecular weights of approximate26.0KDa induced in strawberry leaves treated with1mM SA. On the tenth day,24.1KDa,101.3KDa,103.2KDa increased in leaves sprayed exogenous SA and new polypeptides withmolecular weights of approximate19.7KDa,31.3KDa induced in stress treatments.New polypeptides with molecular weights of approximate26.0KDa induced instrawberry leaves treated with0.1,1mM SA and new polypeptides with molecularweights of approximate98.8KDa induced on SDS-PAGE gel in leaves sprayed1mMSA. To sum up, spraying appropriate concentrations of exogenous SA could alleviatethe damage of water stress on the strawberry plants.