The objective of the present study was to evaluate 44 soybean octuple crosses in the F4:3[8] and F5:3[8] generations in order to select progenies superior for seed oil yield (OY) and other important agronomic characteristics.Octuple crosses were hybridized in a chain mating system.In one group, crosses were carried out for three generations with the adapted x exotic parents until octuple crosses with 75% adapted genes and 25% exotic genes were obtained.In a second group, hybridization of adapted x adapted parents originated crosses with 100% adapted genes.
During the growing season 1994/95, the progenies F4:3[8] were evaluated by using the augmented block design.The progenies F5:3[8] Home Decor were evaluated during the growing season 1995/96 in three experiments using augmented block design without repetition.The octuple crosses gave origin to superior progenies for all the characters studied.In the C22 cross, OY values were 707 kg/ha.
The estimates of heritability in relation to the crosses average resulted in the following mean, minimum and maximum values, respectively: number of days to maturity (52.35%, 3.71%, 84.23%); agronomic value (26.
69%, 1.62%, 61.28%) and grain yield Roper Style Saddle (29.28%, 1.
52%, 61.06%).The observed genetic gains for grain yield in the early, intermediate and late F5:3[8] progenies were superior to the expected genetic gains and the observed genetic gains for OY were more expressive in the early and late F5:[8] progenies.The genetic variability remaining in the selected progenies of some crosses suggests that further genetic gains for grain yield and OY might be possible with advanced selection cycles.