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

Author
item Gesch, Russell - Russ
item JOHNSON, BURTON - North Dakota State University

Submitted to: Field Crops Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/30/2013
Publication Date: 5/8/2013
Publication URL: http://handle.nal.usda.gov/10113/56453
Citation: Gesch, R.W., Johnson, B.L. 2013. Post-anthesis development of oil content and composition with respect to seed moisture in two high-oleic sunflower hybrids in the northern US. Field Crops Research. 148:1-8.

Interpretive Summary: Even after seed on a sunflower head have matured enough to harvest, the leaves and stems of plants are often too wet, making harvest difficult. Because of this a farmer has to wait longer to harvest, which can also mean that the crop is potentially exposed longer to conditions such as bad weather and bird predation that can reduce yields. Therefore, farmers often spray chemical herbicides on sunflower plants as soon as the seed has matured to kill and dry them out (i.e., desiccation), allowing them to be harvested sooner. Our previous work showed that sunflower potentially can be desiccated when seed is at 40% moisture content and has reached physiological maturity (PM), which is a higher moisture content and thus, earlier than currently recommended. However, for economic purposes, it is also important that the oil quality of seed is at or near a maximum before desiccating the plants. Therefore, a two-year field study was conducted in Prosper, ND, and Morris, MN, to determine the moisture content at maximum oil content and quality in seeds of two oilseed sunflower hybrids. We discovered that maximum oil content for both hybrids occurred at seed moisture ranging from 43 to 49% and that the quality of oil was maximized at about the same or even higher moisture content. This means that if a farmer chooses to desiccate sunflower at a seed moisture content of 40%, seed oil yield and quality will not be sacrificed. This information will benefit the agriculture chemical industry to update recommendations for desiccant application, and will be useful to crop consultants and farmers in determining the best time to desiccate sunflower, and this could translate into improved crop yields.

Technical Abstract: Desiccating sunflower (Helianthus annuus L.) at physiological maturity (PM) or as early as possible can be used to hasten harvest and thus, reduce yield loss associated with severe weather, plant degradation, and bird predation. Previous work showed that two modern oilseed sunflower hybrids studied reached physiological maturity (PM) at seed moisture content of about 40% and thus, could potentially be desiccated earlier than current recommendations for sunflower production in the northern U.S. Although some studies have addressed the relationship of oil content and fatty acid composition with the timing of PM, little attention has been given to the relationship of oil characteristics with seed moisture content. Therefore, the objective of the present study was to model 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-yr field study was conducted at Prosper, ND, and Morris, MN, and seeds were collected from capitulum at 4 to 7 d intervals between stages R6 and R9. Maximum oil content of both peripheral and intermediate zone seed occurred at seed moisture ranging from about 43 to 49% depending on the hybrid. The maximum proportion of stearic, oleic, and linoleic acids 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 was reached at higher seed moisture than was previously found to occur at PM, and thus, was established earlier (about 2 to 6 d) during seed development than PM. Therefore, if desiccation of the crop is based on seed moisture content at PM, oil quality should not be sacrificed.