BACKGROUND: Zinc is an essential low-use element involved in the activity of various enzymes. Carbonic anhydrase, which catalyzes the reversible conversion of carbon dioxide and water into carbonic acid, contains zinc and requires zinc for its activity. Zinc plays a role in protein metabolism, gene expression, structural and functional integrity of biological membranes and photosynthetic carbon metabolism. OBJECTIVES: The present study was conducted with the aim of investigating the foliar application of zinc sulfate fertilizer on the amount of proline and zinc element in leaves and the yield of barley cultivars under saline water irrigation conditions. METHODS: This research was done according split plots experiment based on randomized complete block design (RCBD) with three replications was carried out in the Station of Agricultural Research in Kabutrabad, Isfahan. Zinc sulfate application three levels (0, 0.5 and 1%) as the main factor and three cultivars (Armaghan (sensitive to stress), Goharan (tolerant to drought) and Mehr (tolerant to salinity)) were considered as secondary factor. RESULT: The highest content of zinc in leaves (45.9 mg.kg-1) and number of seeds per spike (37.2) was observed with 1% zinc sulfate solution in Mehr cultivar. With 1% zinc sulfate foliar application, Mehr and Goharan cultivars had more leaf proline, 21.3% and 15.3%, respectively, compared to Armaghan cultivar. Foliar appkication of zinc sulfate with a concentration of 1% in Mehr, Goharan and Armaghan cultivars significantly increased seed yield by 22.2, 25.7 and 0.29%, respectively, compared to no foliar application of sulfate fertilizer. CONCLUSION: In general, the results of the research showed that under irrigation water salinity conditions, Mehr varieity was superior to Gohran and Armaghan cultivars in terms of seed yield in response to zinc sulfate application. Manuscript profile

Abstract In order to study the effects of agrophysiological responses of barley genotypes to salt stress and zinc fertilization, a field experiment was conducted in a strip-split-plot design with three replications. Saline irrigation water in three levels [2 (low), 10 (moderate) and 18 (high) dS m-1] were applied as vertical factors. Three barley genotypes [‘Morocco’ (salt-sensitive), ‘Nosrat’ (semi salt-tolerant) and ‘Khatam’ (salt-tolerant)] were arranged within the vertical factors. The horizontal factors were four zinc fertilizer applications [Nano-ZnO, Zn-EDTA, simultaneous applications of Nano-ZnO + Zn-EDTA, and water (control)]. With increasing salinity, maximal efficiency of PSII (Fv/Fm), chlorophyll content (SPAD), relative water content (RWC), K+ ion, K+:Na+ ratio, number of spike (NS), kernel number per spike (KNS), thousand-kernel weight (TKW), and grain yield (GY) decreased, but electrolyte leakage (EL) and Na+ ion concentration increased. The tolerant genotype (Khatam) had maximum Fv/Fm, SPAD, RWC, K+ ion, K+:Na+ ratio, KNS and GY. Minus zinc application (check) had minimum Fv/Fm, SPAD, K+:Na+ ratio and GY. Nano-ZnO had the highest EL and the lowest KNS, K+ and Na+ ions. Zn-EDTA application provided the highest RWC, K+ ion, K+:Na+ ratio, KNS and GY. Overall, it was concluded that Zn-EDTA can be as a proper toolfor increasing barely yield under salinity stress conditions. KeyWords: Barley, Salinity stress, Yield, Zinc applications. Manuscript profile