A study of source and sink relationships to select wheat lines and genotypes for drought tolerance

In current study, 14 genotypes of bread wheat chosen by breeding tests in Zanjan Agricultural Research Institute of Iran were exposed to two experiment under irrigation and late season drought stress. The experiments were conducted between 2012-2013 in a randomized complete block design with three replications. Analysis of variance showed that, under non-stress condition, the differences among genotypes were significant regarding biological yield and grain weight per spike, while under stress condition in addition there were significant differences about grain yield and biological yield at pollination stage. Under normal and stress condition, the highest and the lowest biological yield was observed in genotype 3 (52.6 g per 15 stems), genotype 2 (35 g per 15 stems), respectively. The average weight of grain per spike decreased by 44.38 % under drought stress condition. In flag leaf removal experiment, results showed that the genotypes significantly differed under nonstress condition regarding the spike weight, grain weight per spike and weight of the leaves, except flag leaf, while under stress condition there were significant differences among genotypes in terms of biological yield, spike weight, peduncle weight at pollination stage, grain weight pre spike and weight of the leaves, except flag leaf. In leaves defoliation (except flag leaf), results showed that the differences among genotypes under normal and stress condition regarding spike weight, grain number per spike, biological yield, peduncle weight, and flag leaf weight were significant