Effects of harvest-aids on seed composition in soybean under midsouth USA conditions

Authors: Bellaloui, Nacer; Bruns, Herbert; Abbas, Hamed; Fisher, Daniel; Mengistu, Alemu

Submitted to: Plants
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/4/2020
Publication Date: 8/9/2020
Publication URL: https://handle.nal.usda.gov/10113/7079457
Citation: Bellaloui, N., Bruns, H.A., Abbas, H.K., Fisher, D.K., Mengistu, A. 2020. Effects of harvest-aids on seed composition in soybean under midsouth USA conditions. Plants. 9(8):1-16. https://doi.org/10.3390/plants9081007.
DOI: https://doi.org/10.3390/plants9081007

Interpretive Summary: With the expansion of the use of early maturing soybean cultivars in the mid-South (Arkansas, Louisiana, Mississippi, Missouri bootheel, and west Tennessee), green stems, green pods, or green leaf retention presence at harvest increased. These conditions delay the harvest operation and reduce harvest efficiency, and reduce the grade and market price of the harvested seeds. Harvest-aids (defoliants) are used to avoid such management difficulties. In spite of the benefits of using harvest-aids for harvesting management, their effects on seed composition (seed protein, oil, sugars, and amino acids) constituents were not well investigated. The objective of this research was to investigate the effects of harvest aids on seed composition. To achieve this objective, field experiments were conducted in 2012 and 2013 under Mid-South USA environmental conditions in which different defoliants (paraquat, carfentrazone-ethyl, sodium chlorate, and glyphosate) were applied at soybean growth stages R6 (seed-fill) and R7 (yellow pods). Results showed that application of defoliants at either R6 or R7 resulted in alteration of some seed compositions constituents such as protein, oil, oleic acid, fructose, and some amino acids, though yield was not affected. Defoliants affected seed composition constituents differently, depending on the growth stage. Despite the significant changes (increases or decreases) to some seed composition constituents, the average values of these seed composition constituents from treated and non-treated soybean still fall within the normal, acceptable ranges. This research helps scientists advance our understanding of how seed nutrition is affected by defoliants. The findings did not result in recommended changes to current defoliant management programs, as the current system maintains the nutritional quality of soybean seed used for food or feed.

Technical Abstract: Interest in using harvest-aids (defoliants or crop desiccants) such as paraquat, carfentrazone-ethyl, glyphosate, and sodium chlorate (NaClO3) have become increasingly important to assure harvest efficiency, producer profit, and maintain seed quality. However, information on the effects of harvest-aids on seed composition (protein, oil, fatty acids, sugars, amino acids) in soybean is very limited. Therefore, the objective of this research was to investigate the influence of harvest-aids on seed protein, oil, fatty acids, sugars, and amino acids in soybean. Field experiments were conducted in 2012 and 2013 under Midsouth USA environmental conditions in which harvest-aids were applied at R6 (seed-fill) and R7 (yellow pods) growth stages. Harvest-aids applied included an untreated control, 0.28 kg ai ha-1 of paraquat, 0.28 kg ai ha-1 of paraquat + 1.015 kg ai ha-1 of carfentrazone-ethyl (AIM); 6.72 kg ai ha-1 sodium chlorate, 1.015 kg ai ha-1 carfentrazone-ethyl; and 2.0 kg ae ha-1 glyphosate. Results showed that application of harvest-aids at either R6 or R7 resulted in alteration of some seed composition such as protein, oil, oleic acid, fructose, and little effects on amino acids. In addition, harvest-aids affected seed composition constituents differently depending on year and growth stage. This research demonstrated possible alteration of some nutrients by harvest-aids, although there were no effects on yield. This research helps growers and scientists to advance the understanding and management of harvest-aids and investigate possible effects of harvest-aids on seed nutrition.