Improving barley performance by proper foliar applied salicylic-acid under saline conditions

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Despite general effect of salicylic-acid (SA) in improving plant growth andproductivity in saline conditions, there have not been unanimity about the bestconcentration. In this 2-yr field study the effect of different SA concentrations(0, 0.5, 1.0, 1.5 and 2.0 mM) was examined on growth, grain yield and yieldcomponents of barley under two non-saline (2 dS m-1) and saline (12 dS m-1)conditions. By using response curves and regression analyses the best concentrationwas also determined. The results showed that salt stress decreased barley plantheight (22.7%), fertile tillers (19.0%), ear length (21.6%), grain number per ear(22.5%), thousand grain weight (19.9%), biological yield (29.6%) and grain yield(37.6%). Since salinity treatment when imposed the tillers were at their rapidgrowth phase; therefore, fertile tiller number per unit area was found to be the mostsensitive trait to salt stress. Nonetheless, SA foliar application in differentconcentrations could ameliorate some of these negative impacts on growth, yieldand yield components. Reduction percentage of grain yield due to salinity wasthe lowest at 1.5 mM in first and 1.0 mM SA concentration in second yearcorresponding to 27.3% and 33.8%, respectively; while those were highest at no-SAtreatments (42.2% and 43.8% in first and second year, respectively). Modulating roleof SA for adverse effect of salinity could be attributed to enhanced grain number.Based on the result of regression analysis, it can be concluded that SA foliarapplication at 2.0 mM under non-saline and at 1.41 mM under saline conditionscould be considered as the best concentrations for improving barley performance.