Performance and Analysis of F2 Diallel Cross among Six Faba Bean Genotypes under Orobanche Infested Soil at Giza Research Station, Egypt

Abstract

The present investigation was carried out under the naturally infested field of Orobanche at Giza Research Station during 2013/2014 growing seasons. F2 diallel crosses including reciprocals among six faba bean genotypes (Giza 843, Nubaria 1, Cairo 25, Cairo 5, Cairo 33 and Misr 3) were used to study the performance and reaction of genotypes to Orobanche and to estimate the magnitude of combining ability and type of gene action using diallel analysis. Analysis of variance indicated highly significant differences among the entries for all studied characters. The results showed that the parents Cairo 25, Cairo 5 and Cairo 33 had negative effects of general combining ability (GCA) for earliness in flowering, while the parents Giza 843 and Cairo 25 had positive GCA effects for plant height. Also, the parental genotypes Cairo 5 and Misr 3 were the best combiners for pods/plant, seeds/plant, seed yield/plant and 100-seed weight. The parental genotype Misr 3 was good combiner for Orobanche tolerance. Many crosses had highly significant positive specific combining ability (SCA) effects for most studied traits. The best crosses for SCA effects were                              ( Nubaria 1 x Cairo 5)  and (Cairo 25 x Cairo 5) for  number of branches/plant, number of pods/plant, number of seeds / plant, seed yield/plant, 100-seed weight, number of Orobanche spikes/plot and Orobanche spikes dry weight/plot. Also for reciprocals there were many crosses had positive SCA effects. The crosses (Cairo 5 x Giza 843) possessed reciprocal effects for all studied traits except for days to flowering and Orobanche spikes dry weight/plot. GCA/SCA ratios revealed the predominance of additive gene action for days to flowering, 100-seed weight, number of Orobanche spikes/plot and Orobanche dry weight/plot. Inbreeding improved tolerance to Orobanche. This occurred in tolerant x tolerant, tolerant x susceptible and susceptible x susceptible combinations. Selection can be conducted in segregating generations of hybrid and their reciprocals crosses distinguished for the development of promising high yield crops and tolerant genotypes.