Selection for Seed Yield in Inter‐Gene Pool Crosses of Common Bean

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Abstract
The need to maximize yield of common bean (Phaseolus vulgaris L.) without increasing production costs is increasing in most countries. High‐yielding cultivars tolerant to production constraints are needed. Our objectives, therefore, were to: (i) determine the effects of input levels on selection for seed yield, (ii) compare the relative yield gains in crosses among gene pools, and (iii) study yield stability of selected lines. Six inter‐gene pool crosses of Middle and South American common bean were used. Visual mass selection for seed yield in individual plants was practiced in the F2 and F3 generations. In the F4, single plants were harvested. From F5 to F8, selection was based on plot yields. The six highest‐yielding lines from each cross and each environment were compared with five high yielding parents and four checks at high‐ and low‐input levels over 3 yr (1984–1986). Differences among years, crosses, and lines within crosses were observed for all traits. Under low input, there was a 31% reduction in yield and 7% reduction in seed weight, but maturity was accelerated. Differential anthracnose (Colletotrichum lindemuthianum) pressures did not affect the levels of resistance of selected lines. Selection was effective in both environments, but the two groups of selected lines did not differ in mean yield. Crosses within small‐seeded Middle American (SSMA) and between SSMA and large‐seeded Andean American gene pools did not produce lines yielding more than the highest yielding parent or check. Only lines selected from two higher yielding crosses between small‐ and medium‐seeded gene pools of Middle America outyielded the best parent and check cultivar.