Heterotic Performance and Combining Ability of Two-Way F1 Soybean Hybrids1
- C. R. Weber,
- L. T. Empig and
- J. C. Thorne2
Eight attributes were measured in spaced F1 soybean (Glycine max (L.) Merrill) hybrids and their parents. The F1 hybrids gave an average of 13.4% heterosis for seed yield over their respective high parent in the 85 crosses evaluated. Nearly 77% of the hybrids exceeded the high parent yield. Seed size in large-seeded ✕ large-seeded hybrids was nearly 4% smaller than the large parent, while in small-seeded ✕ small-seeded crosses, the F1's and the larger-seeded parents had about the same average seed size. Thus, an increase in seed number was largely responsible for the increase in seed yield of the F1. Wholeplant dry weight was larger and harvest index was smaller in the hybrids as compared with the high parent, indicating that, while the F1's produced more seed than the parents, their nonseed portion was unproportionately larger than in the parents. The hybrids approximated the midparent average in maturity, were generally shorter than the taller parent, and were not significantly different from the midparent mean in protein and oil contents.
Specific combining ability effects were significant for seed yield, maturity date, plant height, and oil content. Except for oil content, general combining ability estimates were significant and were two to six times larger than specific combining ability effects.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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