Estimation of Genetic Parameters of Grain Yield and Some Agronomic Traits in Bread Wheat Using Diallel Crosses

Abstract

The aim of this study was to estimate of general combining ability (GCA) of the parents, specific combining ability (SCA) of hybrids progeny, heritability and heterotic patterns of grain yield and some agronomic traits considered for the development of high yielding cultivars in durum wheat. A complete diallel crosses set obtained of seven genotypes durum wheat were sown in randomized complete block design in 2006. The results indicated significant differences among the parents, F 1 s for almost of the traits that indicating considerable genetic variation in the used genetic material. Significant mean squares due to Parents vs. F 1 s for show heterotic patterns for these traits. Significant GCA is indicating role of additive gene action in the control of all the traits. The SCA were significant for all the traits with the exception of flag leaf area, spike length, seed filling duration and days to heading. Reciprocal mean squares were significant for the traits except spike length and days to heading. The mean square ratio of GCA to SCA indicated that both of additive and non additive gene effects were important in genetic control of almost of the traits in these crosses. Narrow-sense heritability was moderate to high (0.43-0.70) for Plant grain number and day to heading but low to medium (0.06-0.37) for tiller number, plant height, harvest index and plant grain yield. Among the parents Dipper-6, was the best general combiners for grain yield per plant, Preion-1 for 100-grain weight and harvest index. The best specific cross for grain yield, Harvest index and 100-grain weight is Prion-1 × PI40098. Low or average GCA for almost of the traits for these two genotypes indicating that addition to additive effect, others type of gene action such as dominance, additive × dominance interactions and or maternal effect should be conceded for expression of traits. These hybrids are expected to produce desirable segregants and could be exploited successfully in durum wheat improvement programs.