Potential of wild common bean for seed yield improvement of cultivars in the tropics

Abstract

Thirty nine wild or weedy common bean (Phaseolus vulgaris L.) accessions, representing the two extremes of geographical range of distribution and domestication of cultigens in the Americas, were crossed to a high-yielding, small-seeded cultivar, ICA Pijao. The resulting F 1 , F 2 , and F 3 population bulks, along with ICA Pijao, were evaluated for seed yield, days to maturity, and 100-seed weight under favorable growing conditions at two locations in Colombia. The F 3 and F 4 bulks were tested separately under soil-fertility and moisture stresses. Thirty random F 5 -derived F 8 lines from the highest yielding population involving both Andean and Middle American wild beans, along with the parents and a control cultivar, were also evaluated for 2 yr, under favorable conditions. No F 1 hybrid, population bulk, or F 5 -derived F 8 line significantly outyielded ICA Pijao in any test environment. The mean yield of F 1 hybrids, population bulks, and F 5 -derived F 8 lines involving wild and weedy beans of Middle America was higher than that involving Andean South American wild beans. Heritability for seed yield, seed weight, and days to maturity, as well as gains from selection were comparable to those obtained in crosses among cultivars. The small seed of the progenies and the positive correlation between seed size and seed yield suggest that alternative mating schemes that increase the recovery of progenies with a cultivated phenotype should be investigated. Until this research is done, it would be premature to draw conclusions about the yield improvement potential of wild beans. Key words:Phaseolus vulgaris, common bean (wild), yield, heterosis, heritability, selection gain