الفهرس 
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Abstract
The present study was carried out at Shandaweel Agricultural Research station, ARC, during the two successive growing seasons of 2003/2004 and 2004/2005.
The objective of this study is to estimate mean performance, heterosis, general and specific combining abilities and correlation coefficients between 10 studied characters in a half diallel cross of seven selected parental durum wheat cultivars or lines. The parental lines or cultivars were Sohag-1, Sohag-2, Sohag-3, Bani-Sweif-1, Bani-Sweif-2, Bani-Sweif-3, and Belikh//Gediz/Bit. Parental lines and F1 hybrids were grown in randomized complete block design with three replications. The results obtained could be summarized as follows.
Mean performance:
Days to heading: significant differences were observed among 7 parents and 21 F1 hybrids, the parent Sohag-1, was the earliest one, while the parent Bani-Sweif-3 was the latest one. Meanwhile, all 21 F1 hybrids were intermediate in heading when compared to the respective parents and the cross (P1 x P 4 Sohag-1 x Bani-Sweif-1) was the earliest one.
Days to Maturity: the P1 (Sohag-1) was earliest parent, while, the P6 (Bani-sweif-3) was the latest one. The F1 crosses were significantly different among them and they intermediate in days to maturity when comparing with their respective parents.
Plant height: all F1 hybrids were either taller or intermediate in height comparing with their respective parents
Spike length: the parents 5 and 6 (Bani-Sweif-2 and 3) have the shortest spike length, while the parent no 7 (Belik//Gediz/Bit) has the longest one. Meanwhile, thirteen crosses out of 21 F1 hybrids possessed me tallest spike length when compared with their respective parents.
Number of spikes/plant: the parents 1 & 7 (Sohag-1 and Belikh//Gediz/Bit) had the highest number of spikes/plant, while the parent 2 (Sohag-2) possessed the lowest one in number of spikes/plant. As well as, five crosses oil of from 21 F1 hybrids had the highest number of spikes/plant when comparing with their respective parents.
Number of kernels/spike: the parent 1 (Sohag-1) had the lowest number of kernels/spike (62.97 kernel), while parent 7 Belikh//Gediz/Bit was the highest one (77.47 kernels). Meanwhile, all crosses were intermediate when comparing with their respective parents except 7 crosses were exceeded in number of kernels/spike when comparing with their receptive parents.
1000-kernel weight: insignificant differences were observed among parents, the parent 6 (Bani-Sweif-3) possessed lowest kernel weight (5.17 gm), while, P7 (Belikh//Gediz/Bit) possessed the heaviest kernel weight (5.99 gm). All F1 hybrids were exceeded in kernel weight when compared to the respective parents.
Biological yield/plant: significant differences were observed among parents and their progenies of F1 hybrids. Parent 4 (Bani-Sweif-1) was the lowest one in values of biological yield/plant, while the parent 1 had the highest value. AS well as, in F1 hybrids, thirteen crosses were exceeded in biological yield / plant values when compared with respective parents.
Grain yield/plant: the results showed significant differences among parents and their prognies of F1 hybrids. Parent 2 (Sohag-2) had the lowest values of grain yield/plant, while parent 7 possessed the highest values. In the F1 crosses, seven crosses were higher in values of grain yield/plant comparing the respective parents.
Harvest index: parent no. 2 (Sohag-2), had the lowest values in harvest index, while parent no. 7 (Belikh//Gediz/Bit) possessed the highest value. As well as, in the F1 hybrids, four crosses were exceeded in harvest index when compared with respective parents.
2- Heterosis:
Estimates of heterosis have been done based on both of mid-parents and better or high parent values. Great variation in performance heterosis was observed among all studied genotypes. Results obtained could be summarized as follows:
Days to heading: Eight crosses were earlier than mid-parents, while all crosses were later than earlier parents (High parents).
Days to maturity: Nine crosses were early mature when compared with mid-parents, while, five crosses were early maturing when compared with earlier parent.
Plant height: Significant differences in heterosis were observed in all crosses except five crosses as mid-parent and 12 crosses as high parent. These results confirmed that selection for produced shorter plant could be effective.
Spike length: Twelve and nine crosses had positive and significant differences of heterosis values as both magnitudes of mid-parents and high parent, respectively. These results indicate that selection could be effective in improving spike length.
Number of spikes/plant: Ten and five crosses were positive and significant differences in heterosis as mid-parent and high parent respectively.
Number of kernels/spike: Five and one crosses had positive significant differences in both magnitudes of mid-parent and high parent, respectively.
1000-kernel weight: All F1 crosses possessed positive significant differences except one and four crosses as mid–parent and high parent respectively were insignificant. These results indicating that selection could be effective to development kernel weight.
Biological yield/plant: Ten and five crosses had positive and significant differences in heterosis values in both magnitudes of mid-parent and high parent, respectively.
Grain yield/plant: Twelve and six crosses possessed positive and significant differences in heterosis values based on mid–parents and high parent, respectively. These results indicating that selection could be effective to produce lines have high yield ability.
Harvest index: Nine and two crosses had positive and significant differences in heterosis values based on mid-parent and high parent, respectively.
3- Combining ability:
A- General combining ability.
Highly significant differences were observed among the studied genotypes for all studied characters. GCA was much higher than SCA for all studied characteristics. These findings indicating the contribution of additive and non-additive gene effects towards the genetic variability present in the material under study.
GCA/SCA ratio was higher than one for all studied traits. These results indicating that additive gene effects play important roles in the inheritance of these characteristics. Sohag-1 cultivar was good combiner for days to heading, days to maturity, number of spikes/plant, biological and grain yield/plant. Sohag-2 appeared to be general good combiner for plant height, spike length, 1000-kernel weight and biological yield/plant. Sohag-3, was good combiner for spike length and number of kernels/spike. Bani-Sweif-1 was good combiner for days to heading, days to maturity, and spike length. Bani-Sweif-3 was good combiner for plant height, number of spikes/plant, number of kernels/spike, 100-kernel weight and grain yield/plant. Meanwhile, Belikh//Gedz/Bit line was good combiner for days to heading and number of kernels/spike and this line seemed to be poor combiner for the remain traits.
B- Specific combining ability: -
Ten crosses out of the F1 hybrids showed negative SCA values for days to heading, while eleven crosses appeared negative SCA values in the F1 hybrids.
Plant height: Six crosses having negative SCA values, while 15 crosses having positive SCA values.
Spike length: Fourteen crosses showed positive values in SCA effects, while seven crosses appeared negative values in SCA effects.
Number of spikes/plant: Thirteen crosses having positive in SCA effects, the heights values of SCA effects were observed in the crosses (P1 x P2 Sohag-1 x Sohag-2), (P2 x P7 Sohage-2 x Belikh//Gedz/Bit), and (P4 x P 7 Bani-Swaif-1 x Belikh//Gedz/Bit).
Number of kernels/spike: Eight crosses having positive values for SCA effect, and the highest values were obtained from crosses (P1 x P6 Sohag-1 x Bani-Swaif-3), (P2 x P4 Sohag-2 x Bani-Swaif-1), (P4 x P5 Bani-Swaif-1 x Bani-Swaif-2) and (P6 x P7 Bani-Swaif-3 x Belikh//Gedz/Bit).
1000-kernel weight: Thirteen crosses showed positive values in SCA effect among S1 hybrids .The highest values were obtained from the crosses (P1 x P2 Sohag-1 x Sohag-2) and (P4 x P6 Bani-Swaif-1 x Bani-Swaif-3).
Biological yield/plants: Twelve crosses having positive values in SCA effects, the highest values were in crosses (P2 x P6 Sohag-2 x Bani-Swaif-3), (P4 x P6 Bani-Swaif-1 x Bani-Swaif-3) and (P4 x P7 Bani-Swaif-1 x Belikh//Gedz/Bit).
Grain yield/plant: Twelve and nine crosses shower positive and negative values in SCA effects, respectively, whereas, the crosses (P1 x P3), (P1 x P6), (P2 x P6), (P2 x P7) and (P4 x P5) showed the highest positive values of SCA effects among F1 hybrids.
Harvest index: Ten crosses having positive values in SCA effects .The crosses (P1 x P6), (P2 x P3), (P3 x P7), (P4 x P5) and (P6 x P7) gave the highest SCA effects (3.459, 2.835, 2.877, 6.343 and 7.734), respectively.
4. Genetic Components:
Results of studied genetic components revealed that additive and non-additive gene effects were important in the inheritance of most studied characters. Additive gene effects was important and higher than dominance effects in genetic system controlling of the days to heading, days to maturity, plant height and spike length.
5. Correlation coefficients:
Genotypic correlation coefficients was higher than phenotypic correlation coefficients in most the relationships. Days to heading showed positive and significant phenotypic and genotypic correlation coefficients with each of days to maturity and plant height in the parent and their F1 hybrids. While it had negative correlations with each of spike length, number of spikes/plant, 1000-kernel weight, biological yield/plant, grain yield/plant and harvest index (in the parents).
Days to maturity revealed positive significant correlations with plant height in both magnitudes of correlations, while it had negative correlations with each of spike length, number of spikes/plant, number of kernels/spike, 1000-kernel weight, biological yield/plant, and negative significant with grain yield/plant in both phenotypic and genotypic correlation coefficients.
Plant height showed positive correlations with number of kernels/spike (0.25 & 0.47) in the parents only and biological yield/plant (0.13 & 0.15) for both magnitudes of phenotypic and genotypic correlation coefficients, respectively. Spike length showed positive correlation with each of 1000-kernel weight and harvest index (in the parents only).
Number of spikes/plant exhibited positive correlation coefficients with each of 1000-kernel weight (0.15 & 0.19), biological yield/plant (0.76 & 0.80) grain yield/plant (0.49 & 0.47) in the parents for both magnitudes of phenotypic and genotypic correlation coefficients, respectively. While it had negative correlation, coefficients with each of number of kernels/spike (in the parents and F1) and harvest index (in the parents).
Number of kernels/spike showed positive correlations with each of 1000-kernel weight, biological yield/plant (in the F1’s’ only), grain yield/plant and harvest index.
Grain yield/plant showed positive significant correlation coefficients with each of number of spikes/plant, number of kernels/spike. Biological yield/plant and harvest index in the parent and F1’s’ in both phenotypic and genotypic correlation coefficients, while it having negative correlations with each of days to heading, days to maturity, plant height, and spike length in the ( F1 hybrids).