Predicted and actual yield advance in a bi-parental and backcross-derived soybean population

Improved soybean [Glycine max (L.) Merr.] lines that include a plant introduction as one parent may be derived from a bi-parental (BP) or backcross (BC 1 ) population. The number of BC 1 families may be small in some instances because of a lack of successful crossing. The objectives of our experiment were to (1) compare the mean, genetic variance and distribution of lines from a BC 1 population derived from only a few BC 1 families with those from a BP-derived lines; (2) compare the BP and BC 1 population mean with the mid-parent mean; and (3) evaluate the mean yield of the superior 10% of lines within each population. Two BC 1 F 1 plants were selfed, and 75 random lines were derived from each plant. The mean yield, physiological maturity and plant height of BP-derived lines were greater than the mid-parent means. The genetic variance among BC 1 -derived lines was much smaller than among BP-derived lines. A utility function that combines mean yield and expected genetic gain identified the BC 1 population as the superior population. Key words: Soybean, backcross, bi-parental, genetic gain