Bulk, Pedigree, and Early Generation Testing Breeding Methods Compared in Soybeans1

Abstract

Soybean (Glycine max (L.) Merr.) lines selected from populations advanced by the pedigree, early generation (F4 and F5) testing, and 2 bulk methods were evaluated in the F6 and F7. Differences in the yield of these lines due to method of generation advance were not significant. However, with selection on 2‐year means and in each individual year, the complete bulk (CB) and early generation testing (EGT) methods retained a few more lines than the maturity bulk (MB) and pedigree (P) methods. Methods of generation advance were highly significant for four character‐population combinations but these appeared to occur at random except for seed quality‐maturity in population 6. This association was not unexpected because seed quality and later maturity are significantly correlated in 14 out of 24 cases. Heritability estimates ranged from 10 to 40% for yield, 29 to 88% for height, and 23 to 72% for lodging.We suggest that plant breeders discard approximately 75% of their yield‐tested lines each year. This would permit larger populations to be evaluated and should result in the retention of more stable high‐yielding lines.