Date of this Version
Canadian Journal of Plant Science, 1992, 72(3): 735-741, https://doi.org/10.4141/cjps92-089.
Twenty experimental lines of small-seeded common^bean (Phaseolus vulgaris L.) of Middle American origin from the second cycle of selection (SCS) in multiple cross intra- and interracial populations were evaluated with two control cultivars from the first cycle of selection (FCS) derived from single-cross intraracial populations and three standard controls at three locations for 3 yr (1988-1990) in Colombia. A 5 x 5 lattice design with four replications was used. Each plot consisted of four rows, 5 m long in the first year and 7 m long in the next 2 years. To develop experimental lines in both selection cycles, visual mass selection for seed yield and/or resistance tb diseases in individual plants and plant-to-progeny rows was practiced in early generations. The F2 and F3 were managed by the single-pod bulk method followed by the single plant harvests (F4 or F5), progeny tests (F5 or F6), and seed increases (F6 or F7). The F4- or F5-derived lines were tested for seed yield in F7 or F8. Thirteen lines from the SCS outyielded both control cultivars from the FCS and one standard control. However, only two lines, A 785 and A774, from the SCS outyielded the best standard control, cultivar Carioca, by an average of 7.77o. Both lines were derived from interracial populations involving high-yielding parents possessing positive general combining ability for seed yield. Most improved lines from the SCS possessed higher yield per day and higher disease resistance. No apparent changes were recorded in days to maturity and 100-seed weight for high-yielding lines. Late-maturing lines usually had lower yield and yield per day.