Genetic Parameters of Some Quantitative Characters in Three Maize (Zea mays L.) Hybrids

Six population seeds of three yellow maize hybrids were formed at Agricultural Research Center, Homs, during 2008 and 2009 growing seasons. Their plants were evaluated in 2010. The present work aims to determine the genetic parameters in six populations (P1, P2, F1, F2, BC1, and BC2). Mean square results showed significant differences among mean values for all traits in all crosses. Significant heterosis values were positive and relative comparing to mid and better parent for most traits. The potence ratios exceeded (+1) in all traits and crosses except ear height, indicating thus over-dominance. In breeding, depression values were significant in most traits for Cross-1, while their values were non- significant in all traits for Cross-2 except plant height, and also in Cross-3 except plant height and grain yield per plant. In most traits epestasis or dominance gene action occupied the first rank in the genetic effects in order of importance to cross, with the exception of number of rows per ear, number of kernels per row and grain yield per plant where additive gene action occupied the first rank for Cross-2 and Cross-1 respectively. Therefore, it could be suggested that selection for most studied traits in the subsequent generations will be relatively more effective than in the early generations.

Inheritance of some quantitative characters in durum wheat

This study was carried out at Karahta station of field crops research department General Commission for Scientific Agriculture Researches (G.C.S.A.R.) Damascus Syria during the 2009 -2010 and 2010 -2011 growing seasons to estimate gene action, potency ratios, heterosis and Inbreeding depressions. Five population seeds of two single hybrids (Cham-5 × Azeghar-1), (Bohoth-5 × Gidara-2) were formed by crossing of four inbred lines. The crosses were subjected to randomized complete block design (RCBD) with three replications in order to evaluate plant height (PH), number of grains per spike (GRSP), flag leaf area (FLA), thousand kernel weight (TKY) and grain (p<0.05) yield per plant (GYP). Mean square results showed significant differences among mean values of the five populations for all studied traits in all crosses. Significant heterosis values compared to mid and better parent were observed for all traits with exception of (PH) (5.82, 1.62)%, (GRSP) (27.49 9.66)% and(TKY) (3.05 7.53)% for Cross-1. (GYP) (82.46, 96.63)% for Cross- 2. (GRSP) (9.09 5.14)%. The potency ratios exceeded (+1) in all traits and crosses except (PH) (-2.23) for Cross-2. Indicating that over-dominance towards low placement. The results indicated that Inbreeding depression values were significant for all traits in Cross-1 except for (GRSP) (10.33), and (TKY) (15.23). While its values were non- significant for all traits inCross-2except (GRSP) (25.46*). In most traits epestasis or dominant gene action occupied the first rank in controlling these traits in both crosses. It could be suggested that selection for most studied traits in the subsequent generations will be relatively more effective than in early generations.

Heterosis and inbreeding depression in populations of maize (Zea mays L.)

This research was conducted at the Department of Maize in the General Commission of Science Agriculture Research (GCSAR) Damascus, Syria. The genetic material included parental inbred lines and the first and second (F1, F2) generations of two hybrids of maize to estimate the heterosis, degree of dominance and the inbreeding depression under two treatments of irrigation. Results showed that mean squares of inbred lines P1, P2 and the first generation were non significant for all studied traits, while the variance of the second generation F2 was highly significant under the stress and non stress treatments, The hybrid (IL.275–6×IL.362–6) showed the highest average of yield under stress and non stress treatment, a Positive heterosis effect relative to mid parents and the better parent was recorded for ear height, ear diameter, 100 kernels weight and yield per plant, The degree of dominance showed that the branches per tassel was controlled by partial dominance on the other hand the ear diameter and yield per plant showed the greatest values of inbreeding depression, Results revealed the effective selection among the F2 individuals of the studied hybrids specially the hybrid (IL.275–6× IL.362–6) through the late generations (S5, S6) to get new inbred lines of maize which had dominance desirable alleles to improve yield and it's components especially under water stress conditions.