Cuphea seed yield response to harvest methods applied on different dates

Cuphea, Cuphea viscosissima Jacq. x C. lanceolata W.T. Aiton, is a new crop that produces seed containing oil rich in medium-chain fatty acids. Because cuphea has an indeterminate growth habit, timing of harvest is difficult to determine. The objective of this study was to determine the optimum harvest time and technique for maximizing seed yield. This research was conducted at Prosper, ND, in 2005 and 2006; Carrington, ND, in 2005; and Morris, MN, in 2005 and 2006. The experimental factors were four harvest treatments, direct-nondesiccated (DND), direct-desiccated (DD), swathed (SW), and desiccated-swathed (DSW) applied on three different dates (D1, D2, and D3). Maximum seed moisture was 544 g kg(-1), but seed moisture decreased 181 g kg(-1) as the harvest date was delayed for the DND-harvest treatment. Seed moisture reduction for the SW-harvest treatment compared with the DND-harvest treatment was 216 g kg(-1) for D1. Swathing would be a better method than direct harvest or desiccation to reduce seed moisture at harvest. The harvested seed yields were not significantly different (P <= 0.05) among the DND-, DD-, and SW-harvest treatments. Harvested seed yield reduction was observed only for the DSW-harvest treatment. Swathing is also acceptable since no significant seed yield reduction was observed. Based on the returns after harvest treatments, the DND-harvest treatment may be the most cost effective method to harvest cuphea seeds; however, it is not the most practical due to clogging of harvesting equipment, which slows down harvest.