Evaluation of sink limitation and assimilates distribution of wheat genotypes under terminal drought stress

In order to evaluation the pattern of assimilates distribution to seed under late season drought stress, 11 promising lines of winter wheat along with Orum, Zareh, Mihan, Zarrin and pishgam cultivars were evaluated in two levels of irrigation (full irrigation and cutting irrigation from flowering to maturity) at the Agricultural Research Station of Miandoab during 2013-2015 growing seasons. Experiments were conducted in split plot based on randomized complete block design with three replications. Results showed that water deficit stress significantly increased remobilization rate, contribution of remobilization and source restriction and decreased the amount of spike weight, peduncle weight, sink restriction by removing leaves other than flag leaf, sink restrictions by removing flag leaf, grain yield and harvest index, So that terminal water deficit stress increased remobilization by 45.45 percent and the total yield contribution of remobilization of 18.30 % in normal conditions increased to 43.33 percent under stress conditions. Among the genotypes, Zarrin and Mihan under normal moisture conditions and Mihan genotype under terminal drought stress conditions produced the highest grain yield. In this study under terminal drought stress conditions there were significant positive correlations between grain yield with remobilization rate and contribution of remobilization. It can be concluded that the varieties and genotypes afforded adequate remobilization and contribution of remobilization in grain yield in both conditions, are appropriate for cultivation in optimal conditions, as well as areas that are faced with terminal water deficit stress.