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ARS Home » Southeast Area » Stoneville, Mississippi » Crop Genetics Research » Research » Publications at this Location » Publication #399792
Research Project: Evaluation and Development of Improved Soybean Germplasm, Curation of USDA Accessions and Regional Evaluations of New Genotypes

Location: Crop Genetics Research

Title: Seed yield, quality, and composition as influenced by the harvest-aid paraquat in soybean grown in Mississippi

Author
item Bellaloui, Nacer
item Smith, James - Rusty
item Ray, Jeffery - Jeff
item Gillen, Anne
item Mengistu, Alemu
item Fisher, Daniel
item SINGH, GURBIR - University Of Missouri

Submitted to: Journal of the Mississippi Academy of Sciences
Publication Type: Abstract Only
Publication Acceptance Date: 2/24/2023
Publication Date: 2/24/2023
Citation: Bellaloui, N., Smith, J.R., Ray, J.D., Gillen, A.M., Mengistu, A., Fisher, D.K., Singh, G. 2023. Seed yield, quality, and composition as influenced by the harvest-aid paraquat in soybean grown in Mississippi. Journal of the Mississippi Academy of Sciences. 68:54-55.

Interpretive Summary:

Technical Abstract: Paraquat is used as a harvest-aid to desiccate green tissues for increasing harvest efficiency and maintaining seed quality. However, its application can cause significant crop damage and yield loss if applied too early. Information on how to determine the optimum time for applying paraquat is not well known. Therefore, the objectives of this research were to investigate the effects of the timing (critical stages of seed-fill) of paraquat application on soybean seed yield, seed quality (germination, viability, hard-seed, and seed damage), and seed composition. Field experiments were conducted in 2019 and 2020 at Stoneville, MS. Paraquat was applied at a rate of 0.56 kg a.i./ha at growth stages R6 (full seed-fill), R6.5 (pod cavities completely filled with seeds), or R7 (yellow color/beginning maturity). Cultivars P46A57BX and P48A60X were used. The results showed that the application of paraquat at R6 or R6.5 resulted in significant yield loss for both cultivars in both years, whereas application at R7 resulted in significant yield loss for P46A57BX in both years, but in only 1 year for P48A60X. Seed germination and viability were significantly increased over the control in 2020 for both cultivars at all three application stages, but with mixed effects in 2019. No significant seed damage was observed in any treatment, as seed damage for all treatments was below 2%. Application of paraquat at R6 resulted in significantly higher seed protein, oleic acid, raffinose, and stachyose, but lower oil and sucrose. This research demonstrated that the harvest-aid paraquat significantly reduced seed yield, and increased seed protein, oleic acid, raffinose, and stachyose when applied before growth stage R7. Our estimation indicated that a 1,000-ha farm would have lost over $390,000 in 2019 and this loss would have reached over $430,000 in 2020 with either cultivar if a farmer had sprayed paraquat at R6.5. Therefore, producers should use caution when applying paraquat for harvest efficiency before R7, as they will also likely reduce seed yield the earlier paraquat is applied.