Evaluation Genetic of Early Vigor of Bread wheat (Triticum aestivum L.) using Diallel Crosses

Early vigor is an imperative trait and its role become more important under drought stress condition. Genotypes with better early vigor cover above the soil plane, reduce evaporation of soil surface and increase weed competitiveness. In this research, a half diallel mating design was generated from crosses between seven bread wheat to study the genetic of early vigor. Parents and F1 progenies were planted in greenhouse in a randomized complete block design with six replications and seedling dry weight, seedling length and germination ability were evaluated. Additive and dominant effects significantly affected seedling dry weight and seedling length, while germination ability only affected by additive effect. Results showed that epistasis was significant for all traits. Seedling dry weight, seedling length and germination ability showed high broad sense heritability (0.95, 0.91 and 0.84, respectively). Meanwhile, seedling dry weight and germination ability showed low narrow sense heritability (0.29 and 0.19, respectively) and seedling length showed moderate narrow sense heritability (0.62). Selection in early generations has slow progress due to low narrow sense heritability and presence of epistasis. Consequently, bulk, single seed descent and double-haploid methods are suggested in breeding programs for improving early vigor. Iranian cultivar, Roushan, showed the best early vigor and general combining ability among evaluated cultivars and proposed as one of mating parents in breeding programs to improve early vigor.