Selection of parents and segregating populations of black bean resistant to fusarium wilt with high yield and seed weight
Diallel analysis and field tests have not been used in selecting for resistance to fusarium wilt in common beans (dry beans, Phaseolus vulgaris). Our goal was to select parents and segregating populations of dry bean (common bean) with black seed coat that are resistant to fusarium wilt and have high yield and high seed weight. Eight common bean cultivars and elite lines with some level of resistance to fusarium wilt based on previous evaluations, were used to make crosses in a complete diallel scheme. The 28 populations obtained were evaluated with two controls in trials in the F3 (winter/2012), F4 (winter/2013), and F5 (winter/2014) generations in randomized blocks, with three replications, in plots of two 4-meter rows. The trials were conducted in Santo Antônio de Goiás, GO, Brazil, in a field infested by Fusarium oxysporum f. sp. phaseoli in the winter growing season. Data were obtained on reaction to fusarium wilt, yield, and 100 seed weight. Individual and joint analyses of variance and diallel analysis were conducted on these data regarding reaction to fusarium wilt. Mean values were clustered using the Scott-Knott test. Genetic variability was detected for the three traits. There were significant differences among the general combining abilities of the parents and specific combining abilities of the populations for reaction to fusarium wilt, and the additive and non-additive effects were significant. The CNFP 15867 line is recommended for performing new crosses, because it exhibited a positive estimate of general combining ability (0.39), which indicates that it contributes to obtaining more resistant populations. The populations BRS Esplendor x BRS Expedito and BRS Expedito x CNFP 15867 were the most promising for extraction of lines, because they present high resistance to fusarium wilt (-2.6 and -2.8) and high grain yield (2212 and 2270 kg.ha-1), and acceptable seed weight (21.1 and 20.5 g/100grains).