Association of Alleles for High Stearic Acid with Agronomic Characters of Soybean1

Alleles that control four to sevenfold increases in the content of stearic acid in soybean [ Glycine max (L.) Merr.] oil have been obtained by artificial mutagenesis. The objective of this study was to evaluate the association of three alleles for high stearic acid with agronomic and chemical characters of soybean. Three mutant lines, A6 with 282 g kg −1 stearic acid, A9 with 163 g kg −1 stearic acid, and A10 with 146 g kg −1 stearic acid, each with a different allele at a single locus controlling stearic acid content in the seed oil, were crossed to one of three high‐yielding genotypes with stearic acid content of about 40 g kg −1 . The F 1 plants of each mating were backcrossed without selection to the high‐yielding parent. Pairs of highand low‐stearic‐acid lines were selected from BC 1 F 2 ‐derived lines segregating for a high‐stearic‐acid allele. The pairs of lines were evaluated in a replicated test at three Iowa locations. There were no significant differences in the average yield of the high‐ and the low‐stearic‐acid lines from the A9 and A10 crosses. In the A6 cross, the low‐stearic‐acid lines had significantly greater seed yield than high‐stearic‐acid lines by an average of 7.7%. For the other characters measured, the maximum differences between the mean performance of high‐ and low‐stearic‐acid lines for any of the three crosses were 2.9 days for time of maturity, 4 cm for plant height, 0.3 units for lodging score, 8 mg seed −1 for seed weight, 13 g kg −1 for seed protein, and 1 g kg −1 for seed oil. The stearic acid contents of the BC 1 F 3 ‐derived lines generally were less than those of their donor parent, which indicated that modifying genes may influence this character.