Effect of Maturity in Breeding Mid-Oleic Acid Soybeans in the Mid-Southern US.

The value of soybean [Glycine max (L.) Merr.] seed in the US is based on protein and oil content and quality.  The fatty acid composition of soybean seed affects the oxidative stability, flavor, nutritional value, and industrial use of the oil. Increasing oleic acid content in soybean oil would reduce the need for hydrogenation, a process that creates unhealthy trans fatty acids, and improves its properties as a biodiesel feedstock.  Breeding for mid-oleic acid (~50%) soybean oil has been complicated by sensitivity to temperature during seed-fill.  The literature also indicated that maturity explained a significant part of oleic acid variation.  Therefore, the objective of this research was to assess the optimal target maturity for maturity group IV and maturity group V mid-oleic soybeans for the Early Soybean Production System in Mississippi. Three populations derived from crosses to N98-4445A, donor of the mid-oleic trait, were used.  F₄ -derived lines for early and later maturity were selected from one mid-oleic acid F_2:4 line per population.  This resulted in four to eight early lines per population and three to eight later lines per population.  Field trials were conducted in Stoneville, MS.  Statistical analysis of data from a preliminary replicated field trial showed that early maturing lines and later maturing lines had similar levels of oleic acid and that mid-oleic genotypes can be selected from either maturity group.