Cuphea growth, yield, and oil characteristics as influenced by climate and soil environments across the upper Midwest USA

Cuphea is a potential new oilseed crop rich in medium-chain fatty acids (C8:0 to C14:0) that may serve as a renewable, biodegradable source of oil for lubricants. motor oil, and aircraft fuel. Impacts of climate and soil environment on cuphea growth and development are not well understood. The objective of this study was to evaluate the influence of climate and soil on growth, seed yield, and seed oil characteristics of two semi-domesticated cuphea genotypes [PSR23 and HC-10 (Cuphea viscosissima Jacq. x C. lanceolata W.T. Aiton)] and three wild species [Cuphea wrightii, Cuphea lutea, and C. viscosissima (VS-6-CPR-1)] that show potential for domestication. The study was conducted in 2007 and 2008 at field sites in North Dakota (ND), Minnesota (MN). Iowa (IA), and Illinois (IL). Cuphea PSR23 and HC-10 were direct seeded in the field, while the three wild species were transplanted. The two plantings were treated as separate experiments. Plant growth, seed yield and oil content for the two direct-seeded lines tended to be distinctly greater in MN and ND than IL and IA, which was related more to growth temperature than soil environment. The three wild species generally performed similarly across the four different environments. C. wrightii had the greatest oil content, ranging from 320 to 360 g kg(-1), which was comprised of 59-64% lauric acid. For each genotype, the content of its most prominent saturated medium-chain fatty acid (e.g., C10:0 or C12:0) increased with decreasing latitude of field site. Seed yields for C. wrightii and C. lutea were as high as 1116 kg ha(-1). Combined with relatively high seed oil contents (280-350 g kg(-1)) these species may be good candidates for domestication. Results indicate that PSR23 and HC-10 are more regionally adapted than the wild species studied, which tended to exhibit a greater range of adaptability to climate and soil conditions. (C) 2010 Published by Elsevier B.V.