Submitted to: Journal of Agriculture and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 3, 2009
Publication Date: September 21, 2009
Citation: Bellaloui, N., Abbas, H.K., Gillen, A.M., Abel, C.A. 2009. Effect of Glyphosate-boron Application on Seed Composition and Nitrogen Metabolism in Glyphosate-resistant Soybean. Journal of Agriculture and Food Chemistry. DOI:10.1021/jf901801z. Interpretive Summary: Glyphosate is a nonselective broad-spectrum herbicide used extensively throughout the world for postemergence weed control. Boron is an essential mineral nutrient for plant growth and development, and when it is needed to alleviate boron deficiency, it is sprayed on foliage of crops. Although foliar application of glyphosate plus boron (tank-mixing) can be cost effective, limited information is available on the effect of glyphosate plus boron on boron uptake, seed composition, and nitrogen metabolism in soybean. Results showed that glyphosate plus boron or boron only application increased protein, oleic acid, total amino acids, and individual amino acids proline and methionine in seed. However, oil and linolenic acid concentrations decreased under those treatments compared to the control (plants received no boron and no glyphosate applications). Results suggest glyphosate and boron tank mixing do not inhibit boron uptake and translocation to leaves and seeds, and the inhibitory effect of glyphosate on nutrient uptake and translocation may depend on the particular nutrient mixed with glyphosate. Foliar boron application may compensate for the negative effect of glyphosate on nitrogen metabolism. These results demonstrate that glyphosate plus boron application alters seed composition, nitrogen metabolism, and boron status in leaves and seed. Therefore, under boron deficiency conditions, caused by high heat or drought, glyphosate and boron can be applied together for a cost effective means of alleviating boron deficiency while controlling weeds.
Technical Abstract: Information is limited on the effect of combined foliar application of glyphosate (Gly) and boron (B) on seed composition and nitrogen metabolism in glyphosate resistant soybean (Glycine max(L.)Merr.). Therefore, the objective of this two-year field study was to evaluate the effects of single foliar application of combined Gly and B application at 4 and 8 weeks after planting (WAP) on seed composition and nitrogen metabolism. Results showed that Gly-B or B application increased protein, oleic acid, total amino acids, proline, and methionine percentages in seed. However, oil and linolenic acid concentrations decreased under those treatments compared to the control (plants received no B and no Gly application). Gly-B combined or B treatments increased B concentration in leaves and seed. Also, Gly-B or B treatments increased nitrate reductase activity (NRA) and nitrogenase activity, and resulted in a significant positive correlation between B concentration in leaves and NRA (r=0.54; P<0.0001) and B concentration in leaves and nitrogenase activity (r=0.35; P=0.005). Results suggest Gly-B tank mixing may not antagonize B uptake and translocation to leaves and seeds, and the inhibitory effect of Gly on nutrient uptake and translocation may depend on the ion species and form of the nutrient mixed with Gly. B may compensate for Gly depression effect on NRA. These results demonstrate that Gly-B application alters seed composition, nitrogen metabolism, and B status in leaves and seed. This information is beneficial for soybean seed quality improvement programs and Gly and B application management.