Genetic Analysis for Grain Yield and Some of Its Components in Bread Wheat Under Different Environmental Conditions

Abstract

Seven bread wheat varieties (IPA 95, IPA 99, Abu Graib3, Fatih, Tahady and Taka1) were used in half diallel cross to develop 15 single hybrids. Parents and their hybrids were sown through 2009-2010 and 2010-2011 seasons at Baladroz and Mandely (Dyala Governorate), in each season using randomized complete block design with three replications. Graphic analysis, component of phenotypic variation and narrow sense heritability were estimated for characters: plant height, spike length, number of tillers per plant, number of grains per spike, 1000 grain weight and grain yield per plant. The combined analysis of variance results showed that mean square for environments and genotypes was highly significant for all characters, and the genotype x environment interaction was not significant for all characters except 1000 grain weight. Additive (D) and dominance (H1 and H2) genetic variance components were significant from zero for all characters except 1000 grain weight at Baladroz 2010 for H1, with larger importance of additive genetic variance for plant height, spike length and 1000 grain weight at Baladroz 2009, and there were evidence of presence of epistasis for grain yield per plant (as average of environments) and 1000 grain weight at Mandely 2009, through the close values of H1 and H2 and also the value of H2/4H1 which close to 0.25, and for the same reason the distribution of dominant and recessive genes in parents was symmetric for these two characters and Asymmetric for others. Graphical representation Wr/Vr demonstrated the presence of partial dominance for all characters as the regression line cut Wr axis above the origin point. The narrow sense heritability (as average of environments) was high for plant height, spike length, number of tillers per plant, number of grains per spike, and moderate for grain yield per plant, while for 1000 grain weight, it was high at Baladroz 2009 and Mandely 2010, moderate at Mandely 2009 and low at Baladroz 2010.