Selecting Best Rice Varieties under Drought Stress and Non-Stress Conditions Using Selection Indices

Grain yield and most of the traits that have economic importance in plants, herited as quantity and using direct selection method have not large progress. So, one of the most effective method's indirect selections as improve grain yield with a trait effective on it, is using of selection index. In this research, 42 Iranian local and improved rice varieties were evaluated in randomized complete block design with three replications under two separate conditions, normal irrigation and drought stress during 2014 and 12 traits were measured. Estimating 10 different selection indices based on optimum and base indices in both conditions indicated that selecting for grain yield per plant, 1000-grain weight, number of filled grain per panicle, canopy temperature and number of panicles per plant in non-stress condition and grain yield per plant, 1000-grain weight and number of total spikelet per panicle in stress condition by using their path direct coefficients as economic weights would be a suitable selection criterion for improving of population. Results distinguished that selected varieties based on optimum and base indices in both conditions are almost similar. Thus, optimum and base indices in non-stress condition are proposed as a criterion for selecting high-yield vrieties to use in stress conditions.

Grain yield, Path analysis, Rice (Oryza sativa L.), Selection indices, Stress condition