Ions content and antioxidant response of barley to different methods of salicylic acid application under salinity conditions

Although it has been well-known that salicylic acid (SA) can increase salinity tolerance in barley; there is no consensus on the best method and time of application. Thus, a factorial experiment based on completely randomized design under controlled conditions was conducted at College of Agriculture, Shiraz University in 2014. In this research, the effect of SA at five levels: control (No SA), seed priming, foliar application at complete establishment, double ridges and anthesis was examined on grain yield, sodium (Na+) and potassium (K+) concentration in shoot and root as well as antioxidant enzymes activities of barley cv. Reyhane under three salt stress levels: control, 6 and 12 dS m-1. The results showed that salt stress, depended to its severity reduced Na+ and increased K+ in shootand root and enhanced antioxidant enzymes including peroxidase, catalase, ascorbic peroxidase and superoxide dismutase, so that the most severe salt stress caused 147.4% increase in Na+ and 44.1% reduction in K+. Nevertheless, SA in priming and foliar application could compensate some of these changes and so increased grain yield. For example, seed priming and foliar application at complete establishment, double ridges and anthesis increased K+ by 72.7%, 77.3%, 22.7% and 18.2% and decreased Na+ by 37.8%, 40.5%, 27.0% and 13.5%, respectively. Overall, it can be concluded that the highest positive effect f SA was observed in seed priming and foliar application at establishment, which showed that SA might induce more salt stress tolerance if applied at early growth stages.