Growth and development of cuphea

Abstract

Abstract Cuphea (Cuphea viscosissima Jacq. × C. lanceolata W.T. Aiton, PSR23) is a new oilseed crop being developed for the north-central USA. Cuphea oil is high in medium-chain fatty acids that are suitable for detergent/cleaner applications and have potential for use in cosmetics. Commercialization of cuphea will require a growth staging system to standardize pest and harvest management. A growth staging system is not currently available for cuphea. The objective of this study was to create a simple and descriptive growth staging system useful for individuals involved in cuphea production or research. Experiments were conducted at Prosper, ND, in 2005 and 2006; Morris, MN, in 2005; and Glyndon, MN, in 2006. Growth, development, and growing degree days (GDD) were recorded weekly from planting to harvest. Growth stages were classified as either vegetative or reproductive. A description of each stage was developed according to observations made to the crop regarding development of the main stem. Cuphea required 115 to 168 GDD to reach 50% emergence. Vegetative stages from V2 to Vn are determined by counting the number of nodes on the main stem that have fully expanded leaves. Reproductive staging begins at the R1 stage when the first flower opens on the main stem. This stage occurs at approximately 600 to 800 GDD after seeding. When there are six or seven developing seed capsules on the main stem, the crop has reached stage R2 which is described as “full bloom”. Stage R3 is reached when the first developing seed capsules, from the lower nodes, begin to split open along the upper capsule surface. This occurs at approximately 800 to 1000 GDD after seeding. Stage R4, or physiological maturity is reached at 900 to 1000 GDD after seeding and is described as when approximately one-third of the seed capsules on the main stem are beginning to split open. Stage R5, or harvest maturity, is reached between 1000 and 1250 GDD after seeding and occurs when approximately two-thirds of the seed capsules on the main stem have opened and initial seed shatter has begun.