Application of Selection Indices for Grain Yield Improvement in Bread wheat (Triticum aestivum L.) under Drought Stress Condition

To improve a complex characters such as grain yield with low heritability, indirect selection through other characters and selection index based on different effective traits were used. For this purpose, 96 F3 families derived from Roshan and Kavir crossing, together with parents, F1 and F2 progenies were cultivated. In lattice design with 2 replications under drought stress conditions in research field of Shahid Bahonar University of Kerman at growing season of 2012-2013. In present study, the Smith-Hazel and Pesek-Baker selection indices were computed based on five traits including main spike weight, awn length, flag leaf width, 1000-grain weight and yield. In addition, direct and correlated responses were calculated for the mentioned traits. In Smith-Hazel index awn length and in Pesek-Baker index main spike weight had the highest selection response. The highest estimated relative selection efficiency for improvement of grain yield was obtained via selection for main spike weight and awn length. Main spike weight, awn length and 1000-grain weight showed positive response in all indices, while, flag leaf width revealed negative responses. Thus, selection based on these indices will resulting selection of families with high awn length, grain weight and low flag leaf width. Results showed that Pesek-Baker index had the highest selection efficiency and can be used to select appropriate genotypes in the present cross and bread wheat breeding programs.