Growth and yield response of Cuphea to row spacing

Abstract

Presently, in USA there is no domestic crop source of oil rich in medium chain fatty acids (MCFAs) (i.e., oils composed of triglycerides with fatty acid chains between 8 and 14 carbons long). Several species of the genus Cuphea (Lythraceae) accumulate saturated MCFAs in their seed-storage lipids, and some species grow well in short-season temperate climates. Recent efforts have been successful in semi-domesticating genotypes of Cuphea for crop production. However, little is known about best management practices for production. A 2-year study was conducted in west central Minnesota, USA, 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. Seed yields were not significantly affected by row spacing. Plants in wider rows compensated for yield by producing more branches and seed pods per plant. The number of filled pods 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 US 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.