Monday, November 5, 2007

Changes on Fatty Acid Composition of Developing Borage Seeds.

Peter Gilbertson1, Scott Weinlaeder1, Burton Johnson1, and Marisol Berti2. (1) Department of Plant Sciences, North Dakota State University, Fargo, ND 58105, (2) Facultad de Agronomía, Universidad de Concepción, Chillán, Chile

Borage (Borage officinalis L.) seed oil is rich in gamma-linolenic acid (GLA) utilized mostly in the pharmaceutical, cosmetic, and nutritional industries.  The mature seed has an oil content ranging from 290 to 380 g kg-1 with GLA content between 17% and 25%. The indeterminate growth exhibited on borage plants, results in physiologically mature seed at the base of the stem and new inflorescence development at the apical meristems.  A GLA content of 22% of greater is preferred by commercial processors, and recognizing when maximum GLA occurs during seed development could identify management strategies, pertaining to seeding and harvest timing, to ensuree preferred levels are attained.

The objective of this study was to determine changes onn fatty acid composition of developing borage seeds, with particular interest in changes of GLA content.

The study was conducted over the 2006 growing season at a North Dakota State University field research site near Prosper, ND.  To evaluate seed development, 500 flowers were tagged at anthesis in each of four replicates, for two different flowering dates, spaced two weeks apart.  Harvest dates for seed collections started 5 d after initial anthesis and continued to physiological maturity.  Harvest dates were spaced at 3-d intervals.  Seed collections at each harvest date consisted of approximately 50 seeds from each replication.  Seed oil composition analysis was determined using gas chromatography.

Borage seed contained palmitic, stearic, oleic, linoleic, GLA, eicosenoic, erucic, and nervonic fatty acids.  Analysis of the first harvest date showed seed GLA content increased after 10-d post anthesis.  Seed physiological maturity was attained at 20-d post anthesis or approximately 241 growing degree days.  Maximizing seed GLA occurred at physiological maturity for individual seeds.