Seed Yield, Oil, and Fatty Acids of Cuphea in the Northwestern Corn Belt

Nevertheless, PSR23 still can be considered only partially domesticated. Remaining obstacles include an inCuphea is a potential new crop for temperate regions. It produces determinate growth habit, continued seed shattering, and stores in its seeds medium chain length fatty acids, which currently and only partial self-fertility. are derived commercially from seeds of tropical palms. The growth PSR23 cuphea grows well in west-central Minnesota and yield potential of ‘PSR23’ (Cuphea viscosissima Jacq. C. lanceolata W.T. Aiton) cuphea was known for west central Minnesota (45 35 N latitude), with yields capable of exceeding but not elsewhere. To better understand the range of latitudes in 1000 kg ha 1, when it is planted in early to mid May which PSR23 is adapted, planting date experiments were established (Gesch et al., 2002b), at densities of about 1 to 2 million at seven research farms along a transect from southwestern Iowa to plants ha 1 (Gesch et al., 2003), harvested in late Sepnorthwestern Minnesota (41–49 N latitude) in 2002 and 2003. Seed tember (Gesch et al., 2005), and provided with sufficient yields, seed oil contents, and fatty acid profiles were determined. In rainfall or irrigation to maintain relatively high plant the absence of drought, cuphea grew well vegetatively at most sites, available water throughout the growing season (Sharratt but seed yields tended to be higher in Minnesota than in Iowa. Irrigaand Gesch 2004). Little is known about seed yield potion did not enhance seed yields greatly in Iowa. Low yields due to tential of PSR23 grown elsewhere. The only other pubdelayed planting (mid May to mid June) were apparent only when lished report for seed yield of PSR23 is from its develwater was limited. Oil content of seeds ranged from 28 to 33% and may have been associated inversely with air temperatures during seedopers (Knapp and Crane, 2000a), who listed a seed fill. The principal fatty acid was capric acid, which ranged from 67 to yield of 795 kg ha 1 for an irrigated site at Corvallis, 73% of total oil and was always highest in the colder, northern-most OR (44 34 N). Seed yields of PSR23 cuphea grown sites. PSR23 appears to have better potential as an industrial oilseed near Peoria, IL (40 45 N), have not been as high as crop at higher than lower latitudes because of enhanced yields and those from Minnesota (personal observations). capric acid levels. The earlier ‘IH50’ hybrid of C. viscosissima lanceolata was tested by Roath (1998) at Ames, Iowa (42 00 N). Seed yields ranged widely, from 220 kg ha 1 in 1993 to C and oil palm (Cocos nucifera L. and Elaeis 750 kg ha 1 in 1994. For comparison, adjacent plots of guineensis Jacq.) currently are the sole sources of C. lanceolata ‘LN86’ produced from 200 to 660 kg ha 1 the world’s supply of plant-derived medium chain length of seed. Other experiments with C. lanceolata LN86 fatty acids (MCFA), such as capric, lauric, and myris(Roath, 1998) and ‘LN43’ (Knapp and Crane, 2000a; tic acids. These fatty acids are used in detergents, lubriWebb and Knapp, 1991) indicated that seed yield potencants, cosmetics, and confectionary products. Tempertial was low compared with that for PSR23, as was that ate sources of MCFA would be advantageous to both for C. viscosissima ‘VL90’ (Knapp and Crane, 2000a). industry and agriculture based at higher latitudes. CuHirsinger (1985) performed agronomic trials at Davis, phea (henceforth, “cuphea”), which is a genus of some CA (38 35 N) and Corvallis, OR, on several cuphea 260 species, is a potential source of such fatty acids in species, including C. lanceolata and C. viscosissima, but temperate growing regions (Graham and Knapp, 1989; reported seed yields only in terms of grams per plant. Hirsinger, 1985; Knapp, 1993). He extrapolated these data to suggest that maximum Although some species of cuphea are used in ornamenunit-area seed yield in his experiments was 900 kg ha 1 tal horticulture, and several species have been examined (Hirsinger, 1985, p. 80), but he did not indicate the for agronomic potential (Hirsinger, 1985), the interspespecies, site, and growing conditions associated with this cific hybrid known as PSR23 (Knapp and Crane, 2000a) suggestion. No other published unit-area seed yields for currently is the source of most agronomic studies with PSR23 cuphea, or its parents, are known by our team. this taxon. PSR23 is a cross between the North AmeriSeeds of PSR23 contained about 30% oil when plants can native, summer annuals, Cuphea viscosissima Jacq. were grown in the Willamette Valley of Oregon (Knapp and C. lanceolata W.T. Aiton. Selection following hyand Crane, 2000a), a location whose average daily air bridization resulted in plants whose seed dormancy, temperature during September (TSep), the presumed time seed retention, and self-fertility characteristics were agof seed-fill, is 16.4 C. In contrast, PSR23 seeds typically ronomically superior to those of the parental species. contained 28% oil when grown in west central Minnesota (Gesch et al., 2002b, 2003), where TSep is 15.0 C. When PSR23 was allowed to mature fully (late SeptemUSDA-ARS, North Central Soil Conservation Research Lab., 803 Iowa ber harvest), seeds contained 32% oil in a year when Avenue, Morris, MN 56267, and USDA-ARS, National Center for Agricultural Utilization Research, Peoria, IL 61604. Received 6 Oct. TSep was high (17 C), but 30% oil when TSep was low 2004. *Corresponding author ([email protected]). (15 C) (Gesch et al., 2005). This information suggests Published in Crop Sci. 45:2195–2202 (2005). Crop Ecology, Management & Quality Abbreviations: FAME, fatty acid methyl ester; GDD, growing degree days; GS, gas chromatography; MCFA, medium chain length fatty doi:10.2135/cropsci2004.0593 © Crop Science Society of America acid; PSR23, partial seed retention line #23; TSep, average daily September air temperature. 677 S. Segoe Rd., Madison, WI 53711 USA 2195 Published online September 23, 2005