Development of Sunflower Oil and Composition with Respect to Seed Moisture and Physiological Maturity.

Desiccants/harvest aids are becoming more commonly used to hasten sunflower harvest. The current recommendation is to apply a desiccant (e.g., glyphosate and paraquat) at 35% or less seed moisture at physiological maturity (PM). Desiccating as early as possible without sacrificing yield may be a desirable management practice to hasten harvest thus, avoiding yield-losses due to bird predation, diseases, lodging, and seed shattering. However, it is also imperative that oil yield and composition not be compromised by early desiccation. A field study was conducted at Prosper, ND, and Morris, MN, to examine the development of oil content and fatty acid composition in seed at different positions on the capitulum with respect to seed moisture and PM in two commercial oilseed hybrids (Croplan Genetics 378 and Mycogen 8N272). Across field sites and seed position, maximum oil content occurred between 39 to 44% for hybrid 378 and 49 to 53% for 8N272. Oleic (C18:1) and linoleic (C18:2) acids, which make up about 88 to 92% of the total seed oil composition of these hybrids, reached their highest concentration at even higher seed moisture levels. Maximum total oil content occurred at seed moisture levels that were as much as 10% greater than those at PM. Therefore, desiccating these two hybrids at a seed moisture content corresponding to PM, which we found to be generally higher than presently recommended for desiccation (i.e., 35% or less), should not result in a loss of oil yield or quality.