Wheat yield fluctuations due to source-sink manipulation under water deficit condition

This study was conducted to determine the effect of source manipulation at different growth stages on dry matter remobilization, yield and yield components of wheat. In 2008, two factorial experiments laid out under water stress and non-stress conditions based on a randomized complete block design with three replications. Three varieties named: Fincan, Sysonz, and Gasqugen and three treatments D0 = Control (no defoliation), D1 = leaf defoliation (except flag leaf) at booting stage, D2 = defoliation at anthesis, (D2 = D1), and all leaves defoliation at booting stage (D3 = D1) were used. The results showed that Sysonz demonstrated the highest expressions in traits such as plant density; plant height, 1000-grain weight and biomass as compared to the other varieties, but it presented the lowest grain per plant. The highest and lowest grain yields (1.4 and 1.2 g/plant) were obtained for Fincan and Sysonz under non-stress condition, respectively. Regarding to the defoliation treatments, D0 produced the highest (2.985 g/plant) and D3 the lowest (2.142 g/plant) biomasses. The highest (53.95%) harvest index (HI) obtained for D3. Comparison of defoliations indicated that D3 presented the maximum (40.23) HI was among the other treatments. In respect of stress tolerance indices, Gasqugen had the highest value of stress tolerance idex (STI) and it is concluded that this variety is more stable than the other varieties for the yield performance in various conditions.