Submitted to: Agronomy Journal
Publication Type: Peer reviewed journal
Publication Acceptance Date: 1/30/2008
Publication Date: 6/27/2008
Publication URL: hdl.handle.net/10113/17938
Citation: Berti, M., Johnson, B., Gesch, R.W., Forcella, F. 2008. Cuphea seed yield response to harvest methods applied on different dates. Agronomy Journal. 100(4):1138-1144. Interpretive Summary: Cuphea is a new crop that produces oil much like that of tropical plants. When cuphea flowers and sets seed, it does so over a period of about two months, but it also sheds its seed as it matures. Therefore, we need to determine the best time to harvest cuphea to get the most seed, and how to harvest it without losing too much seed. Experiments were conducted at field sites in North Dakota and Minnesota to determine the best time to harvest and the best method of harvest. It was found that the best time to harvest was about mid September when the number of growing degree units was around 2200°F days. Also it was found that swathing and direct combining without adding chemicals to dry the plants worked best. However, direct combining may save a farmer money and, therefore, is preferred. These results will be valuable to farmers growing cuphea as well as state extension personnel and crop consultants serving to help farmers manage cuphea production.
Technical Abstract: Cuphea, Cuphea viscosissima Jacq. x C. lanceolata W.T. Aiton, is a new crop whose seed oil is 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 three plant-kill dates (KD1, KD2, and KD3) and four harvest treatments (direct-non-desiccated (DND), direct-desiccated (DD), swathed (SW), and desiccated-swathed (DSW)). Maximum seed moisture was 544 g kg-1, but seed moisture decreased 181 g kg-1 as plant-kill date was delayed for the DND-harvest treatment. Seed moisture reduction for the DD-harvest treatment compared with the DND-harvest treatment was 127 g kg-1 for KD1. Seed moisture reduction for the SW-harvest treatment compared with the DND-harvest treatment was 216 g kg-1 for KD1. Swathing would be a better method to reduce seed moisture at harvest. The harvested seed yield was the same for the DND-, DD-, and SW-harvest treatments. Seed yield reduction was observed only for the DSW-harvest treatment. Cuphea could be harvested direct without desiccation at approximately 1200 growing degree days ('C) after seeding, although seed drying would be necessary. Swathing is also recommended, since no seed yield reduction due to swathing was observed; however, economic analysis indicated that direct harvest without desiccation was the most economical harvest treatment. Thus, direct harvest without desiccation is recommended for producers.