Physiological, biochemical and hormonal response of wheat cultivars to foliar application of growth stimulants and zinc nano-chelate under water deficit stress

To investigate the effect of different foliar application treatments to improve drought tolerance in wheat genotypes, a factorial split-plot experiment was conducted based on the randomized complete block design with 3 replications in 2 locations. The main factor was irrigation (normal and water deficit) and the secondary factors were 4 levels of foliar application (control: without foliar application, jasmonic acid, zinc nano-chelate and succinate) and 3 genotypes of barley. Water deficit stress reduced the content of chlorophyll a (9.03%), chlorophyll b (6.66%), total chlorophyll (7.32%) and auxin (4.21%) and increased the catalase (18.18%), superoxide dismutase activity (23.35%), malondialdehyde (7.17%), glucose (5.35%), fructose (4.85%) and sucrose (14.99%) versus normal irrigation conditions. Foliar application of zinc nano-chelate increased chlorophyll a, chlorophyll b, total chlorophyll and fructose content by 15.45%, 15.76%, 14.70% and 41.35% respectively. The highest content of chlorophyll a, chlorophyll b and total chlorophyll was assigned to the Mihan cultivar. Foliar application with zinc nano-chelate in both environments resulted in the highest biological yield and grain yield and the lowest content of abscisic acid. Foliar application line 9 genotypes with zinc nano-chelate had the highest auxin, cytokinin, catalase and superoxide dismutase activity. While foliar application of nano-zinc chelate in the Mihan cultivar led to the highest biological yield, grain yield, glucose content and the lowest amount of malondialdehyde. Therefore, foliar application of zinc nano-chelate along with the appropriate variety can improve grain yield under different environmental conditions.