Estimation of Some Genetic Parameters for phenological, Morphological and productivity Traits in Two Bread Wheat Crosses

The experiment was grown in a Randomized Complete Blocks Design with three replications during two seasons. Generations means analysis method was used to study the genetic parameters for number of days to heading, number of days to maturity, plant height, number of spikes per plant, number of grains per spike and grain yield per plant of two bread wheat crosses Triticum aestivum L. (Gairwel7 x Douma4), (Azaz1 x Soued), Results have shown that both additive and dominance genetic effects were high significant in most evaluated traits, with predominance of the dominance genetic effects’ values. Also, epistatic genetic effects have contributed to inheritance of most studied traits. The signs of dominance and dominance x dominance were opposite in most examined traits indicating duplicate epistasis for all studied traits of the first cross and for number of days to maturity, plant height and number of grains per spike of the second cross, that indicates that the selection for these traits should be delayed after several generations. High phenotypic variations were composed of high genotypic variations and less of environmental variations, indicating the presence of high genetic variability for different traits and less influence of environment. Highly significant heterosis relative to mid and better parents in F1 was recorded for most characters, accompanied with inbreeding depression for all traits in F2. Narrow sense heritability and genetic advance were low in most cases due to the dominant of non-additive genetic action in controlling the genetic variation of the most studied traits.

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.

A study of the Genetic Behaviour of Some Yield Traits in Half Diallel Crosses of Maize (Zea mays L.)

A half diallel set of crosses among six inbred lines of maize were evaluated at the Maize Research Department (G.C.S.A.R.) in Damascus Governorate during 2010 and 2011 growing seasons to estimate heterosis and combining ability components for the number of rows per ear, number of kernels per ear, ear length (cm), ear diameter(cm), 100-kernel weight (g), and grain yield (ton /hec). The inbred lines, crosses, general combining ability (GCA) and specific combining ability (SCA) mean squares were highly significant for all the studied traits, showing the existence of a genetic variance among lines. The ratios of GCA to SCA detected for the studied traits showed the dominance of an additive gene action for all the studied traits except for 100-kernel weight and grain yield which showed the predominance of a non-additive gene action. The heterosis percentage for the studied traits was significant based on mid and better parents. The GCA effects showed that the lines CML.317, CML.371, CML.373 and CML.367 were good general combiners for grain yield, while the SCA effects showed that seven hybrids were the best F1 cross combinations such as (CML.317×CML.371) for grain yield.

Heterosis, potence ratio, phenotypic correlation and path coefficient analysis for grain yield and it's components in barley (Hordeumvulgare L. )

A half diallel set of crosses among six highly diverse barley (Hordeum vulgare L.) genotypes were evaluated at Karahta Research Station, General Commission of Scientific Agricultural Research (GCSAR), during 2010-2011 and 2011-2012 seasons to study heterosis, potence ratio, correlations among traits and path coefficient analysis for number of spikes per plant, number of grains per plant, number of grains per spike, biological yield ,and grain yield per plant. Heterosis effects for seed yield ranged from%-89.52 (T-6669×S-6303) to%16.99 (Arabi abiad mohsan×S-6689) and from%-49.94 (L-6711×S-6689) to %-1. 35 (Arabi abiad mohsan×S-6689) relative to mid and better parents respectively. Potence ratio values ranged from 1.14 (number of spikes per plant) to 3.50 (biological weight) indicating that non-additive gene action was more important in controlling all studied traits. Correlation coefficients among traits indicated that seed yield was positively and significantly associated with each of number of spikes per plant (0.289), number of grains per plant (0.832), number of grains per spike (0.587), and biological yield (0.708) traits. Path coefficient analysis indicated that number of grains per plant trait had high positive direct effects on grain yield.

Evaluation of some genetic parameters for some quantitative traits in two maize hybrids (Zea mays L.)

The research was conducted at the Maize Researches Department, General Commission for Scientific Agriculture Researches (G.C.S.A.R.) Damascus, Syria during the summer growing seasons of 2010, 2011 and 2012. Treatments were arranged in a Randomized Complete Blocks Design with three replications. The research aimed to evaluate genetic parameters for some traits like days to 50% silking, plant and ear height, ear length, ear diameter, number of rows per ear, number of kernels per row, 100 kernel weight and grain yield per plant using generations means analysis of two maize hybrids (IL.292-06 × IL.565-06, IL.459-06 × IL.362-06) to detect epistasis and estimates of mean effect [m], additive [d], dominance [h], additive × additive [i], additive × dominance [j] and dominance × dominance [l] parameters. Results showed that the additive - dominance model was adequate to demonstrate the genetic variation and its importance in the inheritance of most studied traits. Nonallelic gene interaction was operating in the control of genetic variation in most studied traits. The signs of [h] and [l] were opposite in most studied traits for the two crosses. Also, the inheritance of all studied traits was controlled by additive and non-additive genetic effects, but dominance gene effects play the major role in controlling the genetic variation of the most studied traits, suggesting that the improvement of those characters need intensive selection through later generations. The phenotypic variations were greater than genotypic variations for all studied traits in the two crosses, indicating greater influence of environment in the expression of these traits. Highly significant heterosis relative to mid and better parents, respectively was found for all characters, and this accompanied with inbreeding depression for all traits. Narrow sense heritability and genetic advance were low in most of the traits due to the dominance of non-additive gene action in controlling the genetic variation of the most studied traits and this predict low to medium values of genetic advance through selection process.

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.

Heritability, heterosis and genetic advance in three hybrids of maize (Zea mays) that resistant to maize stalk borer Sesamia cretica

The experiment was grown in a Randomized Complete Blocks Design with three replications, to estimate the heterosis, degree of dominance and the inbreeding depression of three hybrids of maize.