POPULATION BULK VERSUS F-1-DERIVED FAMILY METHODS OF YIELD TESTING INEARLY GENERATIONS OF MULTIPLE-PARENT INTERRACIAL AND INTER-GENE-POOL CROSSES OF COMMON BEAN

To simultaneously improve qualitative and quantitative agronomic trait s, markers and gamete selection can be used. However, the effectivenes s of alternative methods of yield testing in early generations must fi rst be investigated. In this study, we therefore determined the relati onships between seed yield of F-1-derived families and of population b ulks in F-2 and F-3 generations. We also compared seed yields of a hig h-versus low-yielding population in F-2 and F-3 with their advanced ge neration (F-7) lines. First, we yield-tested 25 multiple-parent, inter racial and inter-gene-pool populations, each represented by their popu lation bulk, and 24 F-1-derived families, at three locations, in F-2 ( 1993) and F-3 (1994). Each plot of the bulk of each population consist ed of four rows and was replicated twice. The 24 F-1-derived families were randomly divided into six groups of four. The four families of ea ch group were sown together to represent one plot of each replication. But each family was harvested separately and the mean yield of the fo ur families represented the plot yield. Then, based on the mean seed y ield of F-2 and F-3, one comparatively high-yielding and one low-yield ing population were selected. Ten F-4-derived F-7 lines from each popu lation were yield tested at the same three locations in 1995-1996. Pos itive correlations were found between the mean seed yields of F-2 and F-3, and between the seed yield of population bulks and the yields of F-1-derived families in both F-2 and F-3. The mean seed yield of the 1 0 F-4.7 lines from the high-yielding population was significantly high er (P < 0.05) than that of its counterpart from the low-yielding popul ation. Marker-assisted gamete selection for qualitative traits during hybridization and population development in the F-1 can therefore be c ombined with yield selection among F-1-derived families in early gener ations of common bean populations.