Seed yield, oil, and fatty acids of cuphea in the northwestern Corn Belt

Cuphea is a potential new crop for temperate regions. It produces and stores in its seeds medium chain length fatty acids, which currently are derived commercially from seeds of tropical palms. The growth and yield potential of 'PSR23' (Cuphea viscosissima Jacq. X C. lanceolata W.T. Aiton) cuphea was known for west central Minnesota but not elsewhere. To better understand the range of latitudes in which PSR23 is adapted, planting date experiments were established at seven research farms along a transect from southwestern Iowa to northwestern Minnesota (41-49 degrees N latitude) in 2002 and 2003. Seed yields, seed oil contents, and fatty acid profiles were determined. In the absence of drought, cuphea grew well vegetatively at most sites, but seed yields tended to be higher in Minnesota than in Iowa. Irrigation did not enhance seed yields greatly in Iowa. Low yields due to delayed planting (mid May to mid June) were apparent only when water was limited. Oil content of seeds ranged from 28 to 33% and may have been associated inversely with air temperatures during seed-fill. The principal fatty acid was capric acid, which ranged from 67 to 73% of total oil and was always highest in the colder, northern-most sites. PSR23 appears to have better potential as an industrial oilseed crop at higher than lower latitudes because of enhanced yields and capric acid levels.