The effects of drought stress on Effective Traits at Accumulative cumulative Assimilate of Grain in Different cultivars of wheat

The objective of this study was to evaluate the effects of limit irrigation on effective traits on grain weight in two cultivars of wheat. The study was conducted using a split plot design in completely randomized blocks with four replication and 16 treatments. All farm experiments were conducted in agriculture research field of Azad University of Karaj in 2007 cropping season. The main plot treatments consisted of 8 irrigation regimes as control treatment (T1), irrigation in 60 and 80 depletion of soil moisture (T2 and T3), stop irrigation in stem elongation stage (T4), stop irrigation during stem elongation to ripening (T5), stop irrigation in flowering stage (T6), stop of irrigation during flowering to ripening (T7), stop irrigation in grain filling stage (T8) as first factor. The second plot as secondary factor consisted of two wheat cultivars (Chamran and Marvdasht).AsT1 and T2 treatments had the greatest grain filling duration and T5 had the greatest grain filling duration and grain growth rate. Drought stress condition decreased grain filling duration and 1000 weight grain that leads lower grain yields. Results of correlation showed that seed yield is no significantly correlated with grain growth rate. Also seed yield has a positive and significant correlation with grain filling duration (r=0.57) and grain growth rate showed a negative significant correlation with grain filling duration(r=-0.51).