Hybrid Soybean Seed Production: Comparison of Three Methods

Improved methods to produce hybrid soybean [ Glycine max (L.) Merr.] seed could augment several types of research. Two previously described methods, the traditional method and the dilution method, require insect‐facilitated cross‐pollination of ms ms nuclear male‐sterile plants. The traditional method requires a substantial time investment during flowering to remove fertile siblings, and the dilution method requires a substantial amount of land and pollen‐parent seed. Because time, land, and seed are limited, a more efficient method would be valuable. The cosegregation method was developed, utilizing close genetic linkage between the W1 locus and the Ms6 locus. The W1 ___, seedling has a purple hypocotyl; the w1 w1 seedling has a green hypocotyl. The ms6 ms6 plant is male sterile and female fertile. Approximately 97% of the purple‐hypocotyl seedlings, W1 ___, in a line segregating for the w1 and ms6 alleles in coupling phase will he fertile, Ms6 ___, and can be removed as a pollen source at the first‐trifoliolate stage. Our objective was to evaluate and compare the three methods of hybrid soybean seed production for seed yield, efficiency, and hybrid seed purity and quality. We used a randomized complete‐block design (three replications per location, three locations, two years). The cosegregation method gave higher seed yield, better efficiency, and equal or better seed quality (percentage germination, 100‐seed weight) than the other methods. Male‐sterile plants yielded an average of 28.6 seeds plant −1 with the cosegregation method, 18.2 seeds plant −1 with the traditional method, and 9.5 seeds plant −1 with the dilution method. The cosegregation method will be useful in several research areas, including genetic control of complex traits, prediction of parental value, recurrent selection, and commercialization of hybrid soybean.