Assessment of Genetic Effects for Earliness and Yield Traits in F 1 and F 2 Half Diallel Populations of Wheat

摘要

To develop high yielding wheat cultivars, it is imperative to study the genetic makeup of diverse wheat lines,and inheritance pattern of earliness and yield traits under existing environmental conditions. Inheritance of pre- and post harvest yield- associated traits was studied in 6 × 6 F 1 and F 2 half diallel populations using Hayman's genetic analysis. Six diverse wheat genotypes were crossed in a half diallel fashion during 2010–2011. Parental genotypes along with their respective F 1 and F 2 half diallel populations were evaluated during 2011–2012 and 2012–2013 to explore the genetic basis of various traits. Genotypes differed significantly (p ≤ 0.01) for all the traits in both generations. According to scaling tests, additive-dominance model was partially adequate for all the traits in both generations. The significance of additive (D) and dominance (H 1 and H 2 ) components of genetic variance revealed the involvement of both additive and non-additive gene effects for days to maturity, peduncle length, spikelets per spike, grains per spike, grain yield and harvest index. The values of H 2 /4H 1 were lower than optimum value (0.25) for all the traits which indicated the asymmetrical distribution of positive and negative genes among the parental genotypes. However, according to components of genetic variance and Vr-Wr graphs, over-dominance type of gene action was predominant for the majority of the traits. Broad-sense heritability values were greater than narrow sense, which also confirms non-additive gene effects. Prevalence of over-dominance type of gene action revealed that selection could be delayed to later segregating generations to improve yield traits.