Inbreeding, outbreeding and RAPD markers studies of faba bean (Vicia faba L.) crop

Five faba bean genotypes (Vicia faba L.) were selfed for two cycles to produce S1 and S2 generations. A half-diallel cross was carried out among them in each level of inbreeding (S0, S1 and S2) to obtain 10 F1 hybrids. Parental materials as well as their respective F1s were evaluated during the winter season of 2012. All studied traits except total dry seed yield showed significant inbreeding depression after the first generation of selfing (S1). No further decrease was noticed at the S2 generation. In the S1 generation the degree of inbreeding depression was highest for No. of branches/plant (-14.0%) and the least for weight of 100-seeds (-2.7). Some parents showed inbreeding vigor i.e. positive difference between S2 and S1 for some traits in S2 generation. Most studied traits showed significant positive heterosis values over mid-parent. The highest value of heterosis over the mid-parent was detected for total dry seed yield (128.8) and the lowest value of hybrid vigor was shown by weight of 100-seeds (1.2%). Specific combination among the 5 parental genotypes showed the highest value for heterosis for example cross Misr 2 × Giza 429 was the best cross for total dry seed yield, cross Giza 429 × Misr 1 for No. of branches/plant. Giza 429 is the best general combiner for most traits. Some crosses showed heterosis depression i.e. negative heterosis value in some traits. Hybridization among parental genotypes is recommended to be at the S1 or S2 generation. Twelve arbitrary primers produced different degrees of genetic polymorphism among the parental genotypes. A total of 65 amplification products were scored polymorphic. The percentage of polymorphic bands detected ranged from 33% to 100% with an average of 66.47%. The average of amplified bands was 5.42 polymorphic bands per primer. A positive, but non-significant, correlation (r = 0.085) between Euclidean distance and RAPD distance was observed.