Genetic Analysis by Using Half Diallel Cross of Several Faba bean Genotypes ( Vicia faba L.)

Abstract

The study included 6 genotypes of the faba bean (Iraqi, Spanish, Dutch, Turkish, Italian and American) taking numbers from (1 to 6) respectively. Genotypes were planted in two dates. The first was in 20/10/2016 and the second was in 15/11/2016. All the genotypes under study were indeterminate in their nature of growth. Half diallel cross was subjected (Half diallel mating) according to the second method (Fixed Model) suggested by Griffing (1956) for obtaining 15 single cross, in add to their parents . In the second season, Genotypes were planted (parents and F1) included (6 parents and 15 single hybrids) in comparative study at 20/10/2017. Plants were planted in farmer’s field, near of Euphrates river in the Al-suwfia region at Anbar governorate. The experiment was carried out using R.C.B.D with three replications. The aim of the study was to estimate the heterosis, combining ability, genetic parameters, analysis of the path coefficient and genetic diversity for several genotypes of the faba bean. The most important results of the study were the following:- 1. Analysis of variance showed that the mean squares of the genotypes (parents and crosses) were significant at 5% for all studied traits. 2. The parent (Spanish) was earliest in the flowering (46.14 day), and the same parent had the highest mean of number of leaves (131.51 leaf plant-1) , leaf area (34.58 ds2.plant-1) , leaf area index (1.921) , length of pod (16.61 cm) , number of pods (15.493 pod plant-1) , number of seeds pod-1 (5.873 seed.pod-1) , seeds yield (124.11 g plant-1) , biological yield (387.2g plant-1) and yield efficiency(3.589g ds2). The hybrid (Spanish × Dutch) was the earliest produced hybrids in the flowering 50% where the mean number of days for this hybrid was 71.98 days, and the same hybrid recorded the highest mean of the traits leaf area(41.53 ds2.plant-1) , leaf area index (2.307), Dry weight plant (72.84 g.plant-1) , length of pod (24.12 cm) , Number of pods (20.420 pod.plant-1) , Seeds yield(212.33 g.plant-1) , Harvest index (49.88%) and Yield efficiency (5.378 g/ds2) . 3. All hybrids have positive direction of heterosis for seed yield except hybrids (Spanish × Italian) and (Spanish × American). While the (Iraqi × Turkish) hybrid gave the highest positive heterosis for traits (100 seed weight 30.825%), (Seeds yield %85.291) and (Biological yield %68.879). (Iraqi × Italian) Hybrid was superior by giving the highest heterosis values in Plant height14.243%) and number of seeds per pod 69.837%). The (Turkish × American) hybrid gave the highest positive heterosis of the number of pods (39.567%). 4. The results of the genetic analysis showed that parent (Spanish) gave highest effects of the general combining ability in the desired direction for seeds yield (18.764) , and the same genotype in most of the studied traits and the highest positive effect of the III specific combining ability for seeds yield to the hybrid (Spanish × Dutch) was recorded 79.725 , the same hybrid also had effects in the desired direction for most of the traits included in the study. 5. GCA/SCA components were less than one for all the traits under study. 6. Percentage the broad sense of heritability (%H2b.s) was high in all studied traits and ranged from (91.439 to 99.953)% for two traits number of seeds per pod and number of leaves per plant respectively. While percentage the narrow sense of heritability (% H2n.s) was low to medium and ranged between (4.025 and 62.927)% for the number of branches per plant and the number of leaves per plant respectively . 7. There is a clear indication that the genes of over-dominance were dominant in heritability for all studied traits and ranged between 1.032 and 6.603 for the two traits; number of branches per plant and number of leaves per plant sequentially. 8. The values of the genetic correlation coefficient between the traits and seed yield were positive and highly significant except for the flowering and the number of branches per plant where they were highly significant negative and non-significant positively sequentially. 9. The analysis of the path coefficient showed that the traits: number of pods per plant 0.5170, number of seeds per pod 0.5825 and have the highest direct positive effect on seed yield, this result may be indicating that these traits could be used as good selection criteria for breeding and improving seed yield in faba bean, while the number of seeds per pod recorded the total highest for direct and indirect effects. 10. Parents were divided into three different groups based on cluster analysis, the first group included three genotypes, the second group had just one genotype and the third group two genotypes. The results of the cluster analysis showed that genetic distance highest between the two genotypes (Iraqi) in the first group and the (Spanish) in the third group where amounted (89.12) which indicate the genetic distance between two genotypes. As will, the genetic distance in the third group between the genotypes (Spanish and Italian) was (68.87) that’s indicates a genetic distance found between the genotypes of this group, and less genetic distance between genotypes (Turkish and American) amounted to 19.76 in group third 11. The single crosses were divided into six different groups. The first group consisted of one single cross , the second group contained nine single crosses, the third group consisted of only one single cross, the fourth group consisted of two single crosses , the fifth group on one single crosses , the sixth group on one single crosses. Indicator results that highest genetic distance between the hybrid(Iraqi × Spanish) in the first group and the hybrid (Spanish × Dutch) in the sixth group and the genetic distance between them amounted 84.56 , while less genetic distance between two hybrid (Spanish × Turkish) and (Spanish × Italian) where amounted 18.44 .