Evaluation of the Relationship between Kernel Size, Phenological Characteristics and Grain Yield of Local Wheat Genotypes under Water Deficit Stress Conditions

Water deficit is one of the most important abiotic factors limiting growth, which adversely affect growth and crop production. In order to study the relationship between kernel size and phenological characteristics on grain yield, 46 local bread wheat genotypes along with four varieties were evaluated in randomized complete block design with three replications under irrigation and water deficit stress conditions. Phenological characteristics including day to heading, day to flowering, day to maturity and grain filling duration, and kernel size traits including kernel length, kernel width, kernel thickness and kernel length/width ratio were measured. Analysis of variance revealed significant differences among genotypes for the studied traits. Results showed drought led to decreased grain yield (0.49), thousand grain weight (0.29), spike weight (0.28), peduncle weight (0.20), grain filling duration (0.17), kernel width (0.16) and increased kernel length/width ratio as compared with irrigated condition. Stepwise regression analysis revealed that under irrigated condition, spike weight, spike length and plant height justified the majority of grain yield variation, whiles under drought stressed condition grain filling duration and kernel width showed the highest impact on grain yield variation. Factors analysis identified four factors which explained 75.4% of the total variation. On the basis of these results, it is concluded that criteria such as grain filling duration, kernel width, peduncle weight and thousand grain weight could be considered as effective criteria for selecting to improve grain yield in water-limited environments.