Heritability and Genetic Gain of Seed Protein, Oil, and Yield among RIL of Soybean

Soybean is a remarkable crop that is used in many aspects of our everyday lives. The seed protein is used primarily for livestock feed, though it is becoming more available as a meat substitute for human consumption. Soybean oil is used in many products such as plastics, foods, and industrial products. Seed yield is the major trait that is selected for in a breeding program. A population of 239 F₄ derived RIL from the cross of USG 5601T × U99-310255 was used to calculate heritability estimates by parent offspring regression and on an entry mean basis. This population was grown in 2009 as unreplicated F_4:5 plant rows at the East Tennessee Research and Education Center (ETREC) in Knoxville, TN. In 2010, the F_4:6 generation was grown as two replications with two locations, ETREC and Highland Rim Research and Education Center (HRREC) in Springfield, TN. In 2011, the F_4:7 generation was grown at ETREC, HRREC, and at the Research and Education Center at Milan (RECMLN) in Milan, TN. Averaged over two years (2010 and 2011) and 5 environments exhibited a range of 1928.7 to 3033.6 kg ha^-1 with a mean of 2325.7 kg ha^-1for seed yield, 398.4 to 451.8 g kg^-1 with a mean of 426.8 g kg^-1 for seed protein concentration, and 201.1 to 224.6 g kg^-1 with a mean of 213.7 g kg^-1 seed oil concentration. On an entry mean basis, a heritability estimate of 0.85 for seed protein concentration was observed. However, a parent-offspring regression of F_4:6 to F_4:7 revealed an estimate of 0.43 (R²= 0.26). For seed oil concentration, heritability estimate on an entry mean basis was 0.78 and the parent-offspring regression was 0.11 (R²=0.01). Seed yield exhibited heritability estimates of 0.23 (R²=0.09) and 0.38 for parent-offspring regression and entry mean basis respectively. Genetic gains were calculated for all traits through selections for the top 5, 10, 15, and 20% of RILs for seed yield, seed protein, and seed oil concentration. Improvements in these traits were achieved singularly and could be selected for multiple traits when phenotypic correlations are considered.