Effect of zinc sulfate application on grain yield of bread wheat (Triticum aestivum L.) cv. Chamran under terminal heat stress conditions in Ahvaz

To study the effect of zinc sulfate rates on response of bread wheat cv. Cahmran to terminal heat stress conditions in Ahvaz, Iran, this experiment was conducted at the research farm of Agricultural and Natural Resources Sciences University of Khuzestan, Iran in two cropping cycles (2015-2016 and 2016-2017). The experimental design was split plot arrangements in randomized complete block design with four replications. Experimental factors were three sowing dates (29 Nov., 14 Dec. and 30 Dec.) assigned main plots and five zinc sulfate rates (0: Control, 10, 20, 30 and 40 kg.ha-1) randomized in sub plots. Combined analysis variance showed that year had a significant effect on measured traits. Mean comparison of traits in different sowing dates showed that grain yield decreased with delay in sowing date, due to occurrence of terminal heat stress. The highest (6726 kg.ha-1) and lowest (2884 kg.ha-1) grain yield were obtained in the first and last sowing dates, respectively. The results showed that grain yield increased with increasing zinc sulfate rates and the highest grain yield (6724 kg.ha-1) was obtained from application of 30 kg.ha-1 zinc sulfate. Mean comparison of interaction effect of sowing dates × zinc sulfate rate on studied traits showed that the highest grain yield (6508 kg.ha-1) was in the first sowing date and 30 kg.ha-1 of zinc sulfate application, and the lowest grain yield (2958 kg.ha-1) was in the last sowing date and no-zinc sulfate application (Control). In conclusion, the result of the experiment showed that delay in planting of bread wheat cv. Chamran imposed late heat stress and application of 30 kg.ha-1 zinc sulfate reduced heat stress effect and improved grain yield.