Abstract
The harvest of immature seeds was investigated as a means of enhancing rapid generation advance in soybean [Glycine max (L.) Merr.] breeding programs. One objective of the study was to determine field emergence of immature seeds harvested from genotypes adapted to temperate climates when grown in tropical environments. A second objective was to compare pod color and the ratio of seed width (SW) to pod width (PW) and SW to pod thickness (PT) as indicators of the time to harvest immature viable seed. Two cultivars were planted in three environments in the Iowa State University Soybean Nursery at the Isabela Research Center of the University of Puerto Rico. Harvest of seeds began 24 days after flowering (DAF) and continued at weekly intervals until 59 DAF. Two harvest procedures were compared: removing pods from plants, and pulling plants without detaching the pods. Field emergence, pod color, PW, PT, and SW were measured for each harvest procedure, harvest date, cultivar, and environment. There were no significant differences between harvest procedures for average field emergence. Significant differences were observed among environments, cultivars, and harvest dates. The harvest of immature seed 31 DAF resulted in adequate field emergence. The most rapid method of selecting pods with immature viable seeds was to harvest pods that had begun to turn yellow. Pod yellowing occurred about 38 DAF of cultivars.