Abstract:
Drought is the most restricting factor in agricultural production in arid and semi-arid
regions. This research was conducted on 19 facultative and winter wheat genotypes grown
under normal irrigation (N), early post-anthesis (S1
), and late post-anthesis (S2
) drought
stress conditions. The experiments were conducted at Karadj, Arak, and Jolgehrokh
Agricultural Research Stations in Iran, during 2008-11 cropping seasons. Stress reduced
grain number per spike, thousand grain weight, grain weight per spike, harvest index,
biological weight, and grain yield. Effect of environment, irrigation, and genotype on most
of the traits, including grain yield, was significant. Remobilization, efficiency of
remobilization, and pre-anthesis photo-assimilate contribution to grain filling increased
under drought stress condition. Correlation coefficients between those traits and grain
yield were significantly positive under N, S1
, and S2
conditions. Based on different
drought tolerance indices, the improved line Alvd//Aldan/Ias58*2/3/Gaspard was
identified as the most tolerant genotype under anthesis and post-anthesis drought stress
conditions. It also had the highest remobilization, efficiency of remobilization, and preanthesis
photo-assimilate contribution to grain filling under drought stress conditions.
Keywords: Bread wheat, Grain yield, Remobilization, Late drought
