Soybean test weight in relation to genotype, environment, and genotype x environment interaction in the Southern United States

Authors: KOEBERNICK, JENNY - Auburn University; Gillen, Anne; FETT, ROBERY - Auburn University; SEJAL, PATEL - Auburn University; Fallen, Benjamin; PANTALONE, VINCENT - University Of Tennessee; SHANNON, GROVER - University Of Missouri; LI, ZENGLU - University Of Georgia; SCABOO, ANDREW - University Of Missouri; SCHAPAUGH, WILLIAM - Kansas State University; Mian, Rouf; Read, Quentin

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/22/2024
Publication Date: 2/29/2024
Citation: Koebernick, J., Gillen, A.M., Fett, R.A., Sejal, P.J., Fallen, B.D., Pantalone, V., Shannon, G., Li, Z., Scaboo, A., Schapaugh, W., Mian, R.M., Read, Q.D. 2024. Soybean test weight in relation to genotype, environment, and genotype x environment interaction in the Southern United States. Agronomy Journal. 116:1265-1274. https://doi.org/10.1002/agj2.21551.
DOI: https://doi.org/10.1002/agj2.21551

Interpretive Summary: Test weight is a unit of bulk density which is believed to be influenced by several factors including both genetic and environmental factors. Therefore, a subset of the trials in the Uniform Soybean Tests -Southern States was used to detect relationships among seed composition traits of oil and protein, and seed weight with test weight in multi-location environments for four different maturity groups of soybean. Each maturity group test had its own set of individual trials. The results indicate that environment (location and year combination) had a larger impact on test weight than genetic effect in all maturity groups. In all maturity groups the genotype interaction with environment effect was statistically significant, but practically was not as important as genotype or environment effects. Significant relationships between test weight and seed weight in were found in some maturity groups, but not all. A relationship between test weight and oil was found in only two of the maturity groups. However the relationships were not always significant in all trials within a tests. The association between test weight and protein were not consistent among the tests. In the future, a similar study using a diverse panel of varieties that do not change from year to year may shed more light on the influence of seed composition and environmental conditions on test weight. These results clarify the relationship of test weight with important soybean seed traits and will benefit soybean breeders.

Technical Abstract: Test weight (TW) is a unit of bulk density that is influenced by several factors including both genetics and environment. A subset of the trials in the Uniform Soybean Tests -Southern States was used to correlate seed composition traits of oil and protein, and seed weight (SW) with TW to investigate the interaction of these traits in multi environments for four different maturity group (MG) tests. The results indicate that environment (location and year combination) had a larger impact on TW than genetic effect in all MG tests. This difference was much greater in the earlier MGs, compared to MG VI and MG VII which showed only slightly more environmental than genetic effects. In all tests across four MGs, the genotype interaction with environment effect was statistically significant, but practically was not as important as genotype or environment effects. Broad sense heritability estimates indicated that the trait is moderate to highly heritable. Significant negative correlations between TW and SW (MG V, VI, and VII tests), and TW and oil (MG V and VI tests) were observed but not consistent in all environments within these Tests. TW and protein correlations were inconsistent with a negative relationship in MG V but a positive relationship in MG VII. The consistent negative correlation of TW with economically important seed oil indicates that selection for TW may have a negative effect on oil and lead to a decrease in SW. In the future, a similar study using a diverse panel of cultivars that do not change from year to year may shed more light on the influence of seed composition and environmental conditions on TW.