[Genetic Improvement Of Some Quantitative and Qualitative Traits in Soybean Hybrid Populations [Glycine max (L.) Merr.]

This study was carried out at Khrabou farm, Faculty of Agriculture, Damascus University, during the (2010, 2011) growing seasons. Five Egyptian soybean genotypes (GIZA83, S1/10, S30, GIZA111, S12) were crossed in the First season, using half diallel cross method, and the crosses were grown along with their parents in a Randomized Complete Block Design (RCBD) with Three replications to estimate Heterosis, Genotypic and Phenotypic Coefficient of Variation (GCV, PCV), Heritability (Broad and Narrow Sense) and Genetic Advance for: number of days to flowering, number of days to the initiation of first pod, height of first pod, plant height, number of days to Physiological maturity, number of days to full maturity, number of branches per plant, number of pods per plant, number of seeds per pod, 100 seed weight, grain yield, protein and oil content in the seed. Also to study the Phenotypic correlation between these characters. Results showed significant differences among genotypes in terms of most traits, indicating the existence of genetic variation, and the genotypes had good level of variation to be used as important parents in soybean hybridization programme. The studied genetic parameters showed that the heterotic effects in the present investigation were due to additive genes effect for: number of days to flowering, height of First pod, plant height, number of days to Physiological maturity, number of days to maturity, number of branches per plant, number of pods per plant, 100 seed weight and grain yield, whereas they were due to non – additive genes effect for: number of days to the initiation of first pod, number of seeds per pod, protein and oil content in the seed. Both additive and non – additive genes effect participated equally in the hybrid (GIZA83 x S1/10) for number of seeds per pod; in the hybrids (GIZA83 x S1/10, GIZA83 x S30, GIZA83 x GIZA111) for 100 seed weight and in the hybrids (GIZA83 x S12, S1/10 x S30, S30 x GIZA111) for grain yield. Highest PCV and GCV values were observed for: height of first pod, number of pods per plant, grain yield, while number of days to flowering, number of days to the initiation of First pod, number of days to Physiological maturity, number of days to maturity and protein and oil content in seed recorded lowest values for all hybrids. Results indicated that selection for height of first pod for all hybrids would likely to be effective because of high value of narrow sense heritability coupled with (moderate – high) values for genetic advance (GAM), and less effective for plant height (all hybrids except S30 x GIZA111, S1/10 x S30), for ( No.pods per plant, No.seeds per pod, 100 seed weight) in the hybrid (GIZA83 x S1/10), for grain yield ( all hybrids except GIZA111 x S12), for oil ratio in the hybrids (GIZA83 x S30, S1/10 x GIZA111),because of (moderata – high) values of narrow and broad sense heritability coupled with moderate values of GAM. High and positive values for Heterosis because of dominance, were recorded for height of first pod (47.38%), plant height (23.35%) and No.branches per plant (33.3%) in the same cross (S1/10 x S30), for No.pods per plant (121.8%) in the cross (GIZA83 x S12), for grain yield (105.3%) in the cross (GIZA111 x S12).