Genetic Variability, Correlation, Path Analysis and Discriminant Function of F2 Generations Population in Bread Wheat (Triticum aestivum)

Grains of eighteenth f2 generation produced by using factorial mating design through hybridization between six parents as male named [attla (1), milan (2), acsad 8 (3), acsad 17 (4), noor (5) and cross bred-6 (6)] and three parents as female named mexipak (7), aras (8) and ipa 99 (9)] cultivated on 15 nov. 2011 at the agricultural research station/salahaddin university/erbil using a randomized complete block design with three replications in order to select the best hybrids. some growth traits and yield and its components were studied, and the path coefficient analysis, discriminant function and heterobeltiosis were estimated. the results showed significant genotypic, phenotypic and environment variation in all characters. moderate values of heritability in broad sense were exhibited for plant height (52.99%), spike length (49.94%), 1000-grain weight (50.18%) and grain yield/plant (41.65%). high genetic advance were found in grain yield/plant. significant positive phenotypic and genotypic correlation was observed between grain yield/plant and all characters except flag leaf area. the genotypic correlation coefficients were higher than their respective phenotypic ones. phenotypic path coefficient analysis showed that high and positive phenotypic direct effects on grain yield were exhibited only by biological yield/plant (3.24). while highest positive genotypic direct effects on grain yield were exhibited by grain number/spike (0.74) and spike number/plant (0.62). the results of discriminant function indicated that the inclusion of grain number/spike increased the efficiency of the discriminant function by 22.10% than direct selection for grain yield/plant alone, which was used as a criterion for the selection of superior genotypes. the genotypes which gave high values in the selection index also gave a high values in the productivity score. based on that and if we want to select 10% of the better genotypes, we selected [7 × 3], [7 ×5], [7 × 2] and [7 × 6] genotypes which showed also desirable heterobeltoises in most traits in order to continue the breeding for the f3 and next generation.