Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 9, 2009
Publication Date: November 5, 2009
Citation: Paris, R.L., Ray, J.D., Smith, J.R., Boykin, D.L. 2009. High-oil soybean for more efficient energy conversion to soy-based biodisel. Crop Science. 18(4):259-266. Interpretive Summary: Selecting for increased seed yield in soybean is a difficult and time-consuming process. More information is needed to develop faster and easier methods to increase yield in soybean. Understanding the optimum yielding plant type could help breeders better focus their efforts. Associations were discovered among mid-south soybean lines between seed yield and various plant characteristics such as maturity, oil and protein content, lodging (how much the plants lean toward the ground at harvest), and plant height at harvest. In general, high yielding lines had moderate lodging and height (30 inches), and matured late. High yielding lines could have high oil/low protein content, or high protein/low oil content. These findings will allow plant breeders to more efficiently develop highly adapted, higher-yielding soybean varieties.
Technical Abstract: Identifying the soybean [Glycine max (L.) Merr.] plant type most highly associated with seed yield could be useful to plant breeders. The purpose of this study was to retrospectively examine advanced soybean breeding lines from multiple breeding programs across the southern USA to determine what associations exist among specific traits and seed yield, and to better understand the plant type most highly associated with high seed yield. Multiple regression analysis was conducted between seed yield and the following traits: maturity, oil and protein content, lodging, height, seed weight, and seed quality. Analysis was conducted for 15, 17, and 16 lines in 2000, 2001, and 2002, respectively. The breeding lines examined were grown in the Uniform Soybean Tests, Southern States - Uniform IV-S and ranged from mid- to late maturity group (MG) IV. The strongest associations were between seed yield and: maturity, protein content, oil content, lodging, and height. Significant interactions were observed for protein and oil content, and height and lodging. Analyses indicated that the optimum yielding soybean plant type for mid- to late MG IV grown in the southern USA had medium plant height (762 mm) and lodging score (2.5), and a relative maturity of approximately 4.9. High yielding genotypes of the above plant type had high oil (225 g kg-1) and low protein (385 g kg-1) content, or high protein (435 g kg-1) and low oil (190 g kg-1) content. Understanding the optimum height, degree of lodging, and relative maturity will help soybean breeders better focus their breeding efforts, whether selecting for high protein or high oil.