Drought effect on hormone changes and carbohydrates levels in developing grains of two wheat cultivars

During grain development, appropriate water status of soil has key importance for starch accumulation in grains and hormone changes. For this, the study carried out on two Iranian wheat cultivars Pishtaz and Karaj3 in a factorial experiment based on randomized complete block design with three replications under irrigated and drought in a field experiment at research farm of Agriculture College, university of Tehran in Karaj. The aim of this research was to determine grain filling rate, carbohydrates content during different stages of grain filling, yield and its components. Results showed that Pishtaz cultivar in early grain-filling stages had high grain-filling rate, total soluble carbohydrate, sucrose, glucose and fructose in comparison to Karaj3 cultivar under irrigated and drought conditions. Indole-3-acetic acid (IAA) concentration of grains were high at the early stages of grain-filling, but Abscisic acid (ABA) concentration were high at the linear stages, which in this case Pishtaz was prevalent. Grain yield, biological yield, harvest index, 1000 kernel weight and number of kernels per spike in Pishtaz were higher than Karaj3 in two conditions. Results suggested that differences between cultivars in case of grain yield ant its component substantially resulted from variations of hormonal levels IAA, ABA and grain-filling rate.