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

item KIM, KI-IN - University Of Minnesota
item Gesch, Russell - Russ
item Cermak, Steven - Steve
item PHIPPEN, WINTHROP - Western Illinois University
item BERTI, MARISOL - North Dakota State University
item JOHNSON, BURTON - North Dakota State University
item MAREK, LAURA - Iowa State University

Submitted to: Industrial Crops and Products
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/4/2010
Publication Date: 1/1/2011
Citation: Kim, K., Gesch, R.W., Cermak, S.C., Phippen, W.B., Berti, M.T., Johnson, B.L., Marek, L. 2011. Cuphea growth, yield, and oil characteristics as influenced by climate and soil environments across the Upper Midwest USA. Industrial Crops and Products. 33:99-107.

Interpretive Summary: Cuphea is one of the few known plant species that grows in temperate climates and produces medium-chain fatty acids (MCFA) in its seed oil. MCFAs are used to make many commercial products such as soaps and detergents, cosmetics, and lubricants, but also may serve as an excellent oil feedstock for making military jet fuel, which is being highly researched. The only other plant source of MCFAs is tropical palm trees. The cuphea variety PSR23 has a high seed oil content and is currently the best variety to agriculturally produce. However, its seed oil mainly contains one type of MCFA called capric acid. For making jet fuel and other advanced biofuels other MCFAs are also needed, such as lauric and myristic acids. So, if cuphea is used as feedstock for biofuel production, other species or varieties with a blend of different MCFAs will be needed in addition to PSR23. However, we need to know what species or varieties can be successfully grown in the upper Midwest, which is where production will most likely occur. Therefore, we selected three different wild cuphea species that produce the kind of MCFAs necessary for biofuel manufacturing as well as other industrial uses, and that can potentially be grown in the upper Midwest. We then grew the wild species along with PSR23 and HC-10, another semi-domesticated variety, at four different locations (IL, IA, MN, and ND) to determine the type of climate (i.e., air temperature and rainfall) and soil type that each species or variety prefers for growth and yield. Interestingly, we found that the three wild species grew well at all four locations; whereas, PSR23 and HC-10 only did well at the MN and ND sites. Our results indicate that PSR23 and HC-10 are more adapted to a specific region (based on climate and soil type) than the wild species. We also discovered that two of the wild species, Cuphea wrightii and Cuphea lutea, are excellent candidates to undergo domestication because they produce high seed and seed oil yields for a range of MCFAs. This information will help crop breeders to develop other cuphea varieties that can serve as feedstock for producing advanced liquid biofuels, and will offer a new crop for many Midwest farmers to produce.

Technical Abstract: 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 influences of climate and soil on growth, seed yield and 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 [C. wrightii, C. 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). PSR23 and HC-10 were direct-seeded in the field, while the three wild species were transplanted, and 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, indicating a regional adaptation of these genotypes, which was more related to growth temperature than soil environment. The three wild species generally performed similarly across the four different environments, indicating a greater range of adaptability. Cuphea wrightii had the greatest oil content, ranging from 32 to 36%, with a lauric acid content of 59 to 64%. For all genotypes, the content of key saturated medium-chain fatty acids increased with decreasing latitude of field site. Seed yields for C. wrightii and C. lutea were as high as 1100 kg ha-1. Combined with relatively high seed oil contents, results indicate that these species are good candidates for domestication. Results further suggest 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.