Genetic basis of embryo abortion in Glycine max was analzyed using a large Recombinant Inbred (RI) population. RI lines (including three replicates), parental lines (Minsoy & Noir 1) and "Check" cultivars were planted in hill plots. Fifty fruits from each hill were analyzed for reproductive, quantitative traits (number of ovules per pod, number of filled seeds per pod, seed/ovule, and developmental stage and position of abortions). Parental lines differed significantly for traits. Average values for the RI population were intermediate between the parents. Some segregants had high frequencies of four ovules or seeds per pod, whereas parents and "Checks" did not. There was a positive correlation between yield and ovules per pod and between seed number and ovules per pod. No correlation was observed between variation in pod size and seed/ovule. If abortion occurred within a pod there was a greater probability that another abortion would occur at the same developmental stage. Most abortions fell in the first position within the fruit. Abortions were observed at all developmental stages, but primarily occurred at two of four stages. Six significant QTLs were associated with reproductive traits. QTLs accounted for 36% of the variation in ovule or seed number. Two QTLs were involved in interactions with another locus.

Key words: Glycine max, QTL, reproduction, seed abortion, seed/ovule, soybean