Genetic analysis for F2 generation in barley using full diallel crosses system in Sulaimany-Iraq

Five two rowed barley (Hordeum vulgare L.) were sown in full diallel cross including reciprocals at Qlyasan research station to produce 20 crosses. Analysis of Variance for full diallel cross during the winter season of 2014-2015, 25 genotypes (F2S +5 parents) were sown in a completely randomized block design (CRBD) with three replications at Qlyasan location. The analysis of variance indicated that the mean squares for genotype and SCA were highly significant for all characters and also it was highly significant for most studied characters due to GCA and RCA mean squares. Parent 4 and 5 recorded maximum values for most studied characters, while parent 1 and 3 recorded the lowest value for most characters. The diallel cross 1x2 recorded the highest value for grain weight/plant with 14.640 (g) and its components number of tillers/plant and number of spike/plant with 13.67 and 10.800, while the diallel cross 3x4 gave the highest value for weight of grains/spike , average spike weight and harvest index with 1.633(g), 1.727(g) and 0.546 respectively. The diallel crosses 1x3, 1x5 and 2x3 exhibited lowest value for most characters. The reciprocal crosses 5x2 and 5x4 gave the highest value for most studied characters. Maximum positive GCA effect values for grain weight/plant with 1.273 and some its components exhibited by parent 4, while parent 1 gave maximum negative GCA effect values for grain weight/plant with -1.136 and some its components. The cross 2x5 produced the highest positive SCA effect values for grain weight/plant with 2.798 and some its components , and maximum negative SCA effect values for grain weight/plant with -3.196 and most its components produced by the cross 1x5. The cross 2x1 gave the highest positive RCA effect values for grain weight/plant with 2.597 and some its components, while the cross 5x4 gave the highest negative value due to grain weight/plant with -2.572 and some its components. Parent 4 gave the highest value due to the variance of effect of general combining ability for grain weight /plant with 1.61992 and some its components , while parent 2 showed the lowest value due to the variance of effect of general combining ability for grain weight/plant with 0.00668 and some its components. Parent 2 exhibited maximum the variance of effect of specific combining ability for diallel crosses for grain weight/plant with 6.312 and most its components, while parent 4 gave the lowest value for the variance of effect of specific combining ability for diallel crosses due to grain weight/plant with 0.390 and most its components. Parent 5 produced the highest the variance of effect of specific combining ability for reciprocal crosses for grain weight/plant with 6.464 and most it s components, while parent 2 gave The ratio of the variance of general combining ability/The variance of specific combining ability values were lessees than unity for all studied characters, while the average degree of dominance values for almost all characters were more than unity, indicating the predominance of non-additive gene effect in the inheritance of these characters. Heritability in broad sense was found to be high for all characters, while heritability in narrow sense was found to be low to moderate due to all characters, signifying the importance of hybridization method to improve these characters. The grain weight/plant correlated positively and high significantly with grain weight/ spike, number of spike/plant, number of grains/spike , and biological weight/plant , while correlated positively and significantly with harvest index. The character number of spike/plant gave the highest positive direct effect in grain weight/plant produced by grain weight/spike via biological weight/plant.