Post-anthesis development of oil content and composition with respect to seed moisture in two high-oleic sunflower hybrids in the northern US

• We determined the relationship between seed oil content and quality to that of seed moisture in sunflower.
• Maximum oil content of seeds on the capitulum occurred at moisture contents ranging from 43 to 49%.
• The maximum proportion of stearic, oleic, and linoleic acids occurred at higher seed moisture than total oil content.
• Maximum oil quantity and quality were reached about 2–6 days earlier than physiological maturity.

Desiccating sunflower (Helianthus annuus L.) at physiological maturity (PM) or earlier can be used to hasten harvest and thus, reduce yield losses associated with severe weather, plant degradation, and bird predation. Previous work showed that two modern oilseed hybrids studied reached PM at seed moisture content of about 40% and could be desiccated earlier than current recommendations for sunflower production in the northern U.S. However, the effects of early desiccation on oil content and quality are not well understood. Therefore, the objective of the present study was to determine the relationship between seed oil and moisture content of seed from the peripheral and intermediate zones of the capitulum in two high-oleic sunflower hybrids and evaluate fatty acid composition with respect to seed moisture. A 2-year field study was conducted at Prosper, ND, and Morris, MN, and seeds were collected from capitula at 4- to 7-d intervals between stages R6 and R9. Maximum oil content of both peripheral and intermediate zone seeds occurred at moisture contents ranging from about 43 to 49% depending on the hybrid. The fully developed proportion of stearic, oleic, and linoleic acids in the seed oil was established at as high or higher seed moisture than total oil content regardless of hybrid or seed position. Results indicate that maximum oil content and fatty acid composition for the two oil hybrids were reached about 2–6 d earlier than PM. Therefore, oil quantity and quality will not be compromised if desiccation of the crop is based on seed moisture content at PM.