Influence of harvest aid on soybean seed quality affected by delayed harvest and environment in Louisiana

Harvest aid application can expedite soybean (Glycine max) harvest and increase efficiency through both weed and crop desiccation and has become a common practice in Louisiana soybean production systems. Field studies in 2019–2020 evaluated the influence of harvest aid application (none, paraquat at 0.28 kg/ha, sodium chlorate at 6.72 kg/ha, or saflufenacil at 0.0498 kg/ha) on seed quality affected by delayed harvest (∼20, 30, or 44 days after optimum harvest timing, i.e., 13% seed moisture). Environment was investigated in both field (natural rainfall events) and environmentally controlled growth chambers (79 or 90°F with 30% or 100% relative humidity and exposed for 24, 48, 72, 96, or 144 h) for potential impacts of prolonged rainfall conditions on soybean seed quality at harvest. Seed quality was based on a rating scale of 1 to 10 where 1 means seed in good condition and 10 means seed in poor condition based on USDA reference images. Harvest aid application had no effect on soybean seed quality affected by delayed harvest and saturated (100% relative humidity) environment. Delaying harvest beyond approximately 20 days in the field past optimum harvest timing can result in reduced seed quality regardless of whether harvest aid application occurred (0.52–2 vs 4.18–5.91 rating). In addition, seedpod exposure to high relative humidity conditions (100%) for as little as 96 h after optimum harvest timing can result in severe seed quality issues (3.96 or greater rating) regardless of whether harvest aid was used.