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United States Department of Agriculture

Agricultural Research Service

Research Project: DEVELOPMENT OF SOYBEAN GENEOTYPES AND MANAGEMENT SYSTEMS FOR EARLY SEASON AND STRESS ENVIRONMENTS

Location: Crop Genetics Research Unit

Title: Soybean seed protein, oil, fatty acids N and S partitioning as affected by node position and cultivar differences

Authors
item Bellaloui, Nacer
item Gillen, Anne

Submitted to: Journal of Agricultural Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 24, 2010
Publication Date: November 10, 2011
Citation: Bellaloui, N., Gillen, A.M. 2011. Soybean seed protein, oil, fatty acids N and S partitioning as affected by node position and cultivar differences. Journal of Agricultural Science. 1:110-118.

Interpretive Summary: Soybean is a major source of high quality protein and oil, and its value is determined by seed protein and oil content. Previous studies showed that soybean seed protein and oil qualities and quantities significantly vary as function of node position. However, the source of this variability is not yet understood, and the literature about seed protein and oil distribution (partitioning) along the main stem is still controversial. Understanding the mechanisms of this variability would allow for selection for higher seed composition qualities and more accurate seed composition determination for developed breeding lines. At full seed maturity (R8), soybean line DT97-4290, and cultivars Hutcheson and Stressland had higher percentage of protein and oleic acid and lower percentage of oil and linolenic acid in the top node seed compared with the bottom node seed. For example, the change of protein in the top node compared with the bottom node ranged from 15.5-19.5%, 7.0-10.5%, 14.2-15.8%, 11.2-16.5%, respectively for DT97-4290, Hutcheson, Stressland, and TracyM. Except for TracyM, the increase of oleic acid in the top node ranged from 45.4 to 93%. The change in the top node seed compared with the bottom node ranged from 14.4 to 26.8% for oil and from 5.7 to 34.4% for linolenic acid, depending on the cultivar. The higher protein and oleic acid concentrations in the top node seed was accompanied by higher nitrogen assimilation, higher chlorophyll concentration, higher nitrogen and sulfur percentages in the fully expanded leaves at R5-R6, and higher seed nitrogen and sulfur percentages in DT 97-4290 and Stressland. The current research suggests that the partitioning of protein, oil, and fatty acids percentage in nodes along the plant may depend on the position of node on the main stem, cultivar, seed N and S status, and leaf tissue N and S partitioning. This information is useful for germplasm evaluation of soybean breeding lines, especially for single plant selection.

Technical Abstract: The mechanisms controlling the partitioning of seed composition constituents along the main stem in soybean are still not well understood. Therefore, the objective of this study was to investigate seed protein, oil, and fatty acids partitioning in soybean cultivars. The cultivars were DT 97-4290, maturity group (MG) IV; Stressland, MG IV; Hutcheson, MG V; TracyM, MG VI. Seed was harvested based on position on the plant (top nodes, middle nodes, and bottom nodes). At R8, DT97-4290, Hutcheson, and Stressland had higher percentage of protein and oleic acid and lower percentage of oil and linolenic acid in top node seed compared with bottom node seed. The increase of protein in top node compared with the bottom node across the two experiments ranged from 15.5-19.5%, 7.0-10.5%, 14.2-15.8%, 11.2-16.5%, respectively for DT97-4290, Hutcheson, Stressland, and TracyM. Except for TracyM, the increase of oleic acid in the top node ranged from 45.4 to 93%, depending on the cultivar. Conversely, the decrease in the top node seed ranged from 14.4 to 26.8% for oil and from 5.7 to 34.4% for linolenic acid, depending on the cultivar. The partitioning trend of seed composition constituents at R6 was inconsistent. Except for Stressland, seed oleic acid was higher at R6 than at R8. The higher protein and oleic acid concentrations in the top node seed was accompanied by higher activity of nitrate reductase activity (µmol nitrite g fwt-1 hour-1), higher chlorophyll concentration (g gfwt-1), higher nitrogen (N) and sulfur (S) percentages in the fully expanded leaves at R5-R6, and higher seed nitrogen (N) and sulfur (S) percentages in DT 97-4290 and Stressland. The current research suggests that the partitioning of protein, oil, and fatty acids percentage in nodes along the plant depended on the position of node on the main stem, cultivar/genotype differences, seed N and S status, and tissue N and S partitioning. This information is useful for soybean germplasm for selection of desirable seed constituent traits and for seed composition determination in breeding lines.

Last Modified: 8/22/2014
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