Abstract
This experiment involved implementation of a full diallel crosses between five genotypes of bread wheat in the 2009-2010. Then the parents and their F1 generation including reciprocals were cultivated in the 2010-2011 growing season at the Agricultural Research Station in Koya / Erbil under rainfall conditions using a randomized complete block design with four replications. Some growth characters, grain yield and its components were studied. Genetic statistical analysis were done to estimate general combining ability (GCA) of the parents and specific combining ability (SCA) of F1 hybrids and reciprocals, also the genetic variance components (additive and dominance), environmental variance, average degree of dominance, heritability in broad and narrow sense, expected genetic advance, heterosis and genetic correlation coefficients among the characters were estimated. The results showed that some parents exhibited positive and high GCA, while some hybrids showed SCA for the majority of the characters. The values of additive genetic variance was more than the values of dominant genetic variance for days to flowering, days to maturity, plant height, spike length, 1000-grain weight, and harvest index. While the values of dominance genetic variance was more than additive for flag leaf area, number of spikes per plant, number of grains per spike, biological and grain yield per plant. The values of heritability in broad sense were high for all characters, while heritability in narrow sense was high for some characters but moderate for others. The values of average degree of dominance was greater than one for flag leaf area, number of spikes per plant, number of grains per spike, biological and grain yield per plant. The expected genetic advance was moderate for plant height, spike length, and 1000-grain weight. Grain yield per plant revealed a significant positive correlation with flag leaf area (0.921), number of spikes per plant (0.883) and 1000 grain weight (0.698).
