Estimation of Heterosis and combining ability for yield and some fruit traits in tomato hybrids (Lycopersicom esculentum Mill.)

The research was conducted at Al-Jmmaseh station – the Agricultural Research Center in Tartous- to estimate heterosis, combining ability of yield and some fruit traits. Fifteen hybrids were produced by half diallel crossing method in 2013. These were evaluated in 2014. Most hybrids were characterized by highly significant heterosis values for all the studied traits compared with mid parents and better parents. Heterosis reached (87.76, 50.13)% for yield per plant, (71.44, 43.09)% for average of fruit weight, (19.67, 12.31)% for fruit length, (38.21, 21.43)% for fruit diameter, and (32.5, 20.46)% for number of locules per fruit in comparison with mid parents and better parents respectively. The best hybrids were: (Ou×H) (Ou×W) (Or×H) and maybe they could be promising hybrids if they had superiority in other important traits. Variance due to general and specific combining ability were highly significant for all traits. This ensured that both types of genetic action (additive and non-additive) controlled the inheritance of these traits. σ2GCA/σ2SCA ratio of the additive genetic action overcame the one of non-additive cation in these traits: number of locules per fruit, average of fruit weight and fruit diameter, while the non-additive genetic action was superior in fruit length and total yield.

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.

Estimation of Combining Ability in Al-Salamoniah Maize (Zea mays L.) Hybrids for Some Quantitative Traits Under Two Dates of Nitrogen Fertilizer Application

This research aimed to evaluate the general and specific combining ability components for six inbred lines and 15 hybrids produced by a half diallel cross method, and was conducted during 2010-2011 seasons, in the Department of the Maize Researches at G.C.S.A.R. Damascus . The evaluation included the grain yield, ear height, ear length, and silking under two different treatments of nitrogen fertilizer (1- addition of 50% of N-fertilizer with sowing and the other 50% one month after sowing. 2- addition of 50% of N-fertilizer 18 days after sowing and 50% one month after sowing).and 3 replicates. Results indicated that: Mean squares of inbred lines, and hybrids were highly significant for all studied traits under two adding dates of nitrogen fertilizer, which indicated the presence of genetic distance among parental lines. The ratios (
2 GCA/
2 SCA) showed that additive gene effect was more important than non-additive gene effect in controlling all studied traits except grain yield which showed dominance of non-additive gene effect under tow dates. Many of significant positive GCA effects were obtained for all traits, therefore, it could be concluded, that the inbred lines CML.330, IL.26-09 and CML.334 seemed to be the best general combiners for grain yield. The hybrid (CML.368 × IL.215-09) had showed the best specific combining ability effects for grain yield under the first date, while the hybrid (CML.330 × IL.26-09) showed the best SCA effects under the second date. The second adding date of nitrogen fertilizer (50% 18 days after sowing and 50% one month after sowing) had surpassed of the first date (50% with sowing and 50% one month after) with significant effects for grain yield trait.

Inheritance of grain yield and its components in line by tester method of maize (Zea mays L.)

This study was carried out at the Scientific Agriculture Research Center, Al-Ghab, Syria, during 2013 –2014 growing seasons to estimate heterosis, combining ability, phenotypic correlation and path analysis for 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 for eighteen hybrids produced by the line × tester method, the major findings were: inbred lines, testers, hybrids and combining ability mean squares were significant for all traits, indicating that additive and non-additive gene actions were the important in inheritance of all traits. The ratios of σ2 GCA/σ2 SCA showed that non-additive gene action was more important in controlling all traits except of number of kernel per row. Heterosis percentage for all traits were significant compared with the check variety except of ear height trait. GCA effects showed that the lines P1 and P7 were good combiners for grain yield per plant, also, SCA effects showed that P2×P8, P5×P8, P4×P9 and P1×P7 crosses were the best F1 combiners for grain yield per plant. Results of phenotypic correlation and path analysis values showed that ear length, ear diameter and number of kernel per row were positively and significantly associated with grain yield per plant, also, these traits can be considered as selection criteria may lead to the improvement of grain yield in maize.

Estimate Some Genetic Parameters for Grain Yield and Some of Its Contributing Traits in Bread Wheat Crosses

The Experiment was conducted during the successive growing seasons (2013/2014- 2014/2015) where half–diallel hybridization was conducted between eight genotypes of bread wheat.

Genetic analysis for yield and its components in hybrids of chickpea (Cicer arietinum L.)

A half diallel making design was used to determine combining ability and heterosis of six chickpea lines and their hybrid combinations with R.C.B.D. in three replication for seed yield per plant, number of pods per branch, pods number per plant, first pod height and 100- seed weight, during 2015 and 2016 seasons, at the research Center of Al-Gab (G.C.S.A.R). Genotypes, general (GCA) and specific (SCA) combining ability mean squares were significant for all studied traits. The ratio σ2 GCA / σ2 SCA were detected for all traits and showed that non- additive gene action was more important than additive gene action in controlling all studied traits. GCA effects showed that the lines P2(IL.10158) was good general combiner for number of pods per branch and plant, also, 100- seed weight where, P3 (IL.5883) and P4(IL.4) were good general combiner for first pod height and seed yield per plant, respectively. SCA effects showed that(P1×P2) hybrid was the best F1 crosses combination for seed yield per plant. On the other side (P1×P2), (P1×P4) and (P2×P4) were showed positive and significant heterosis values for seed yield per plant and 100- seed weight also first pod height and number of pod per branch and plant respectively.

Combining Ability and Heritability of Some Productivity Characters in Some Hybrids of Cotton (Gossypium hirsutum L.)

The research was carried out at Tal Hedya Research Center in Aleppo, General Commission for Agriculture Scientific Research (GCSAR), Syria, during 2011 and 2012 seasons. Seven genotypes of cotton were used, and complete diallel hybridization was made to study general and specific combining ability of some productivity traits (sympodial branch number, actual boll number and seed cotton yield). General combining ability (GCA) indicated that the parental genotype Cherpan432 had a high significant GCA for sympodial branch number and actual boll number, but the parents Aleppo118 and Deir El-Zour22 had the high GCA for seed cotton yield. This is a clear indication that these parental genotypes had the largest number of additive genes action, which plays important role in the inheritance of the above-mentioned traits. The estimation of SCA values showed favorite and high significant values in many hybrids resulted from parents, which had highly significant GCA, which means that the gene action type is (additive x additive), and this refers that these hybrids possessing the largest number of additive genes. High heritability broad sense refers to importance of genetic variance in the inheritance of all characters, but heritability in narrow sense values were low in general, indicating the importance of dominance and epistasis genes in the inheritance. According to this result it is recommended to follow the cross method for improvement of the studied traits.

General and Specific Combining Ability and Genetic Parameters (Zea mays L.) of Single Crosses in Corn

Six inbred lines of maize namely; A (1), B (2), C (3), D (4), E (5) and F (6) were used in half diallel cross. The seeds of inbred lines and its single cross hybrids were cultivated in an experiment using randomized completely block design (RCBD) with three replicates, at Twaitha Research Station, Plant Breeding Improvement Center, Iraq, during autumn season (2016). The parents and F1 were significantly differed at 5% for number of days to tasseling and silking, plant height (cm), ear diameter (cm) and yield per plant. Some hybrids showed a significant desirable heterosis for studied traits such as days to tasseling and silking. While plant height and yield per plant for all hybrids showed a significant desirable heterosis (deviation of F1 from mid parents). The mean squares of general and specific combining ability were highly significant for all traits. The additive and dominance variances were differed from zero for all studied traits. The broad sense heritability values were high for all studied traits. Narrow sense heritability was moderate for number of days to tasseling, plant height and ear diameter, but it was low for number of days to silking and yield per plant. The average degree of dominance was higher than one for all traits.

Combining ability analysis for seed yield and some yield compenents traits in six lines of chickpea (Cicer arietinum L.)

A half diallel making design was used to determine combining ability and heterosis of six chickpea lines and their hybrid combinations with R.C.B.D. in three replication for seed yield per plant, number of pods per branch, pods number per plant, first pod height and 100- seed weight, during 2015 and 2016 seasons, at the research Center of Al-Gab (G.C.S.A.R). Genotypes, general (GCA) and specific (SCA) combining ability mean squares were significant for all studied traits. The ratio σ2 GCA / σ2 SCA were detected for all traits and showed that non- additive gene action was more important than additive gene action in controlling all studied traits. GCA effects showed that the lines الإسباني was good general combiner for traits:seed yield per plant, pods per plant, 100- seed weight, days to maturity, protein per cent. SCA effects showed that(Algerian×Spanish) hybrid was the good specific combiner for seed yield per plant, pods per plant, 100- seed weight, harvest index. On the other side(Algerian×Spanish) was showed significant desirable heterosis values for seed yield per plant and 100- seed weight, days to maturity, harvest index.