Submitted to: Field Crops Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/15/2002
Publication Date: 11/27/2002
Citation: GESCH, R.W., FORCELLA, F., BARBOUR, N.W., VOORHEES, W.B., PHILLIPS, B.S. GROWTH AND YIELD RESPONSE OF CUPHEA TO ROW SPACING. FIELD CROPS RESEARCH. 2003. v. 81. p. 193-199. Interpretive Summary: Cuphea plants are unique in that their seeds accumulate large quantities of medium carbon chain length oils. They also grow well in short-season cool climates. The type of oil Cuphea accumulates is in great demand by the United States chemical manufacturing industry for producing such products as soaps and detergents. Yet the U.S. does not grow any domestic crops that produce this type of oil. Thus, the U.S. imports this oil, which is presently extracted from palm tree related species and also from petroleum. Newly developed varieties of Cuphea could serve as a domestic source of oil for manufacturing soaps and detergents and other products. However, little is known about the best agricultural management practices to use for producing it as a viable crop. Therefore, we are conducting research that will lead to optimum protocols for Cuphea production in the northern Corn Belt. A two-year field study was initiated in Morris, Minnesota, in 1999 to determine optimum row spacing for Cuphea production. Our results indicate that plant population density rather than between row spacing may have a greater impact on seed yield. Due to lack of effective chemical weed control at the present time, wide rows are recommended so that mechanical weed control can be used. Our results will greatly benefit farmers by developing Cuphea as an additional rotation crop for the northern Corn Belt, and will also allow the U.S. to be less dependent on imported sources of oil.
Technical Abstract: Presently, the U.S. does not have a domestic crop source of oil rich in medium-chain fatty acids (i.e., oils composed of triglycerides with fatty acid chains between 8 to 14 carbons long). Several species of the genus Cuphea (Lythraceae) accumulate saturated medium-chain fatty acids in their seed-storage lipids, and some species grow well in short-season temperate climates. Efforts to semi-domesticate genotypes for crop production have been successful. However, little is known about best management practices for production. A two-year study was conducted in west central Minnesota, U.S., to determine optimum inter-row spacing for row culture production of Cuphea. Seed was sown in inter-row spacings of 0.125, 0.25, 0.375, and 0.50 m in 1999, and a fifth spacing of 0.75 m was added in 2000. In 2000, seed yield averaged nearly 1000 kg ha**-1, which was about 40% greater than in 1999. In both years row spacing did not have a significant affect. Plants in wider rows compensated for yield by producing more branches and seed pods per plant. The number of filled capsules per plant was as much as 70% greater for plants in the widest as compared to the narrowest row spacing. Data indicate that this was due in part to competition among plants for available light and nutrient resources. Row culture of Cuphea in the northern Corn Belt of the U.S. appears favorable. However, due to its indeterminate habit, growth and yield of Cuphea in row culture may be more responsive to plant population density than inter-row spacing.