Selection index for choosing segregating populations in common bean

The objectives of this work were to determine the viability of using a selection index based on the sum of standardized variables in common bean breeding programs, and to identify the most promising segregating populations for grain productivity, plant growth habit and resistance to lodging simultaneously. Segregant populations obtained by crosses in partial diallel scheme (6x6) were evaluated. Parental genotypes were divided in two groups. Group I comprised parents of the carioca grain type, with semierect to prostate growth habit. Group II comprised parental lines with erect architecture, but with grains not classified as the standard carioca type. The F2 and F3 generations of the obtained hybrid combinations were evaluated in randomized block design, with three replicates and sowing in November 2007 and February 2008, respectively. Data of grain yield, score for plant growth habit and score for lodging were standardized per plot (Z(ij)). The selection index for the three characters together was obtained from the Z(ij) sum. This selection index makes it possible to choose superior segregating populations considering grain yield, scores for plant growth habit, and for lodging simultaneously. Segregating populations CV III 8511 x BRS 7762 Supremo, CV III 8511 x RP 166 and CV III 8511 x RP 26 are identified as promising for breeding programs for grain productivity, plant architecture, and resistance to lodging, simultaneously.