Because of the day-length effect, Group V soybeans begin to flower earlier than Group VII cultivars. Planting a Group V cultivar late in the season can result in a shorter plant due to the early initiation of flowers. Late planting is more likely to be successful when later maturing cultivars are chosen. Regardless of the cultivar, only 25 to 50 percent of the flowers produced will fertilize and develop into a pod. In some cases the flower abortion rate can be as high as 80 percent.
Final yield is primarily dependent on the number of seeds per pod and seed size.
Producers should be able to find small pods approximately 10 to 14 days after the first flowers appear. Approximately 50 to 80 days are required for a flower to progress to a mature pod. However, this interval is highly variable between cultivars, environments, planting systems, and other considerations. Seed dry weight accumulation begins around 10 days after flowering and continues for 4 weeks. For more information, call your county Extension office listed in your telephone directory.