EFFECTS OF TIME COURSE SALICYLIC ACID ON THE ANTIOXIDANT DEFENSE SYSTEM IN BARLEY ROOTS UNDER SALT STRESS

Soil salinity is one of the major abiotic stress types causing significant crop losses. To understand tolerance mechanisms occuring in plants during salinity stress is significant for choosing and improving tolerant species decreasing serious loosings in yield and quality in crops. Salicylic acid (SA) is an important signalling molecule affecting physiological and biochemical processes in many abiotic stresses including salt stress. In this study, how altered the growth parameters, proline amount, and the activities of antioxidant defense system enzymes (superoxide dismutase (SOD), peroxidase (POX), catalase (CAT), ascorbate peroxidase (APX),glutathione reductase (GR)) in roots of barley (Hordeum vulgare L. cv. Kalayc？, Erginel, Akhisar) cultivars with the application of pre- and simultaneous treatment of SA was investigated. Salt stress caused a decrease in growth parameters in all cultivars of barley. It was identified that Kalayc？ was the most tolerant and Akhisar the most sensitive genotype against the stress. Moreover, the effect of time-dependent application of SA on the antioxidant defense system has been established. As a result, SA reduced the salt-induced oxidative damage caused by salt stress by stimulating the antioxidant defense system. This effect differed according to the application time of the SA and genotypes. Especially pretreatment of SA displayed higher tolerance to salt stress and this effect was more observed in Kalayc？ among cultivars