الفهرس 
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Abstract
Five faba bean genotypes were chosen to make crosses in all combinations between them. The genotypes of faba bean are Giza-716, Giza-717, Giza-843, Sakha-1 and Triplewhite. These genotypes obtained from National Legume Research Program at the Agricultural Research Center in Egypt involved a full diallel design and crossed in the season of 2002/2003 in the screenhouse of Mattana Agricultural Research Station to obtain F1 seeds. The seeds of F1 hybrids were sown in the season of 2003/2004 to produce F2 seeds. In the 3rd season, 2004/2005, the experiment was carried out including 45 genotypes of the five parents and 20 crosses of both F1 and F2 to study the genetic system and types of gene effects controlling earliness of faba bean (Vicia faba L). The characters of study divided into two categories of both morphological and yield characters. The six morphological traits included number of days to flowering, first flowering and first fruiting nodes, number of branches per plant, plant height and number of days to maturity. The five yield traits included number of pods and seeds/plant, number of seeds per pod, weight of 100-seeds (Seed Index), and seeds yield/plant.
The results included the mean performance of all genotypes, the heterosis of mid- and better-parent and inbreeding depression, the genetic parameters, and the analysis of Wr and Vr graphs. The data of all traits were analyzed for general and specific combining abilities according to Griffing’s (1956) Method 1 Model 1. the genetic components were computed according to Hayman (1954). The graphic analyses were done according to Mather and Jinks (1971). The correlations among traits were done in order to show the relationship among them and use it to serve the purpose of this study. The results showed highly significant differences between faba bean genotypes overall morphological and yield traits. These differences give the opportunity to obtain better combinations of crosses than their parents which helped achieving the target of this study. Concerning the morphological characters, Triplwhite was the earliest flowered genotype with an average of 42.33 days to 50% of flowering and its offspring of (Giza 843 × Triplewhite) was earlier than its parents with an average of 39 days to 50% of flowering.
The heterosis effect of days to % flowering showed that (Triplewhite × Giza 843) gave the highest negative value of heterosis according to mid-parent (-17.96%), while the heterosis value according to the better-parent was (-7.09%), affirming that Triplwhite was the earliest flowered genotype. The value of inbreeding depression for maturity was 4.03%, for the cross (Sakha-1 × Giza-843), significantly exhibit gain for earliness that show the highest decreasing of number of days to maturity compared to their parents. The results of the combining ability for flowering revealed that both Sakha-1 and Triplewhite are good combiners for earliness. The highly significant value of additive effect ”D” indicating that additive gene action was more important than the non-additive in controlling the inheritance of flowering. The analysis of Wr/Vr graph for flowering show a sharp discontinuity in the distribution of points representing the five parents along the Wr/Vr regression line and showing Triplwhite as the parent that it posses the highest dominant alleles for earliness. However, the graphs of first flowering and first fruiting node detected that Giza-717 as the parent that it posses the highest dominant alleles for earliness followed by Sakha-1 and Triplwhite, respectively. The graph of number of days to maturity affirmed the result of first fruiting node that Giza-717 as the parent that it posses the highest dominant alleles for earliness.
Concerning yield traits, Triplwhite genotype possessed the highest number of pods per plant with an average of 35.80 pods per plant. The highest cross for number of pods per plant (Sakha-1× Giza 843) with the value of 70.5 pods per plant followed by Giza 843 × Giza-717) with the value of 65.21 in the first generation and the cross (Giza 843 × Triplewhite) was the 3rd higher cross with an average of 60.42 pods per plant. However, (Triplewhite × Giza 843) gave the highest number of pods per plant achieving the main target of combine the earliness and high yield. The heterosis effect of number of pods per plant showed that (Giza-843 × Giza-716) gave the highest positive value of heterosis according to mid-parent (218.99%) and (151.86%) according to better-parent affirming that Giza-843 and Giza-716 constitute the best comabatibility in the preferred yield trat. The less value of inbreeding depression of 4.27% recorded for the cross (Giza-716 × Triplewhite), significantly exhibited gain for higher number of pods per plant. The results of the general combining ability for flowering revealed that both Giza-843 and Giza-717 are good combiners for high number of pods per plant. The highly significant value of ”D” indicating that additive gene action was more important than the non-additive in controlling the inheritance of high number of pods per plant. The regression line of seed yield per plant for F1 cuts the Wr axis below the point of origin, indicating an over-dominance effect. There was a sharp discontinuity in the distribution of the points representing the five parents along the Wr/Vr regression line. Sakha- was located at the opposite end, indicating dominance, while parents Triplewhite, Giza-717 and Giza-717 were located in a position at the end of the line, indicating recessiveness for seed yield per plant, but Giza-843 formed a separated group. Apparently, major genes for earliness might be differentiating the three groups of parents. For F2, the slope of wr/vr regression line was not deviating significantly from both zero and from unity with b = 0.506 ± 0.317 indicating the lack of non-allelic gene interaction. The regression line cuts the Wr axis in a position near the point of origin indicating an almost complete dominance. There was a sharp discontinuity in the distribution of the points representing the five parents along the Wr/Vr regression line. Parents 2 (Giza-717), 4 (Sakha-1), followed by parent 1 (Giza-716) were located at the opposite end, indicating dominance while parent 5 (Triplewhite) was located alone in a position at the end of the line, indicating recessiveness but the parent 3 (Giza-843) formed a separated group under the middle of the line. Apparently, major genes for weight of seeds per plant (yield) trait might be differentiating the three groups of parents.
Finally, the negative correlatins between some characters such maturity and seed yield per plant in F2 is logic. However, there is opportunity to use this relationship in improving the productivity of faba bean through selection. The variation between plants in F2 is very high and we can find transgressed segregation in some crosses and use it for further breeding programs. Under some circumstances, the earlier and less yield genotypes that have resistance to a sort of pressure may be more preferred than those late and high yield genotypes that have susceptibility to that sort of pressure.