GENETIC ARCHITECTURE AND DETERMINATION THE NUMBER OF DOMINANT AND RECESSIVE GENES OF WHEAT GRAIN YIELD AND IT'S COMPONENTS (Triticum aestivum L.).

Abstract

Six bread wheat lines and their half diallel crosses were grown by using Randomized Complete Block Design with three replications for estimating genetic parameters and the nature of gene action according to Hayman approach (1954) through graphical analysis by dividing the distance between two points of intercepted regression line and parabola curve into four parts and then estimating the amount of dominant and recessive genes exactly for each parent. The results showed that genotypes differed significantly among themselves, other than significant additive variance components were in flag leaf area,No.spikes.plant-1,spike length, and 1000grain weight, while dominance significant in flag leaf area and No.grains.spike-1,though dominance variance (H1) more important than (H2). Positive F values in No.spikes.plant-1,spike length and 1000grains weight indicated of dominant genes than recessive which that confirm by high ratio of average degree of dominance (a‾) (more than 1 in all studied traits that means existence of over dominance, also high ratio of KD/KR refers to abundance of dominant genes more than recessive one in parents of No.spikes. plant-1, spike length, No.grains. spike-1 and 1000grain weight. Heritability in narrow sense were in flag leaf area (0.291), 1000grain weight (0.425) , 1000 grain weight(0.425) and low in no.grains.spike-1 and grain yield.plant-1.Parent (6) exhibited best performance in plant hieght,flag leaf area, and no.spikes.plant-1, also higher in no.grains.spike-1 and superior in grain yield.plant-1 and possessing large amount of dominant genes controlling these traits.