شاخص انتخاب برای بهبود عملکرد آفتابگردان در شرایط نرمال و تنش شوری

     One of the effective indirect selections methods for improving grain yield and its components is the selection index. In order to develop a suitable selection index for simultaneously increasing yield and its related traits, 100 sunflower inbred lines from different geographical origins were evaluated in randomized complete block designs with three replications at Urmia University in 2015 under normal and salt stress (8 dS/m) conditions. Smith-Hazel and Pesek-Baker indices based on 6 traits including plant high, head diameter, leaf number, one hundred seed weight, head dried weight and grain yield, as well as direct and correlated response of these traits were calculated in each one of salt stress conditions. Correlations between grain yield and selection indices were computed. The highest correlated responses were observed for plant height via seed yield (32.16) and for grain yield via head diameter (14.21) at normal and salt stress conditions, respectively. Head diameter with the highest correlated response for seed yield at normal and salt stress conditions can be considered as a suitable indirect trait for improving seed yield under both conditions. Smith-Hazel’s third indices and Pesek-Bakker’s third indices showed high heritability (0.76, 0.78), genetic correlations (0.87, 0.88) and relative efficiency (0.87, 0.88) and they help to identify the most superior genotypes same to direct selection by grain yield (16, 18) under both conditions. So, selection based on these indices potentially screens the high yielding lines. Based on results, the line ’71’ is introduced as superior line in normal and salt stress conditions.