Abstract

Twenty winter wheat genotypes were evaluated under both post-anthesis drought stress and normal conditions in Ardabil Agricultural Research Station in two successive growing seasons 2005 - 2007 using randomized complete block design with three replications. The results showed that there were significant differences between genotypes in stem reserve under both normal and post anthesis drought stress conditions. Post-anthesis drought stress did not affect kernel numbers per spike. The rate of dry matter accumulation by kernels considerably decreased by water deficit. Dry weight of vegetative organs decreased in grain filling period under stress and normal conditions, contrasting anthesis stage. But, the rate of translocated dry matter was much higher in genotypes nos. 14, 15, 16, 18, 19 and 20 under drought stress condition. 1000 GW and weight of kernels per spike were more severely reduced by water deficit. The positive correlation of grain yield with grain weight per spike, 1000 GW, remobilization of dry matter, harvest index and stress tolerance index (STI) and significant negative correlation of grain yield with drought susceptibility index (SSI) revealed that selection must be exercised for high harvest index, grain weight per spike, 1000 GW, remobilization of dry matter and STI in stress condition. The negative correlation of ‘STI’ with ‘SSI’ indicated the efficiency of ‘STI’ as a selection criterion for identifying the drought tolerant with high yield potential in winter wheat genotypes.

Key words: Winter wheat, drought stress, dry matter, remobilization.