Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/1/2004
Publication Date: 9/1/2004
Citation: Sharratt, B.S., Gesch, R.W. 2004. Water use and root length density of cuphea influenced by row spacing and sowing date. Agronomy Journal. 96:1475-1480. Interpretive Summary: Cuphea is a potential new crop enriched in medium-chain fatty acids (MCFA) that are used to manufacture personal care and nutritional products. Although domestication began a decade ago, virtually nothing is known about the adaptation of and best agricultural management practices for Cuphea. Cuphea was found to produce more seed, develop a denser root system, and use water more efficiently when sown earlier rather than later in the spring in the northern US Corn Belt. Compared to other oilseed crops, Cuphea utilizes water less efficiently as a result of its indeterminate growth habit. Cuphea production under dryland conditions in the northern US Corn Belt must be increased before this crop becomes an economic and renewable source of MCFA in the American pharmaceutical industry. Federal and state plant breeders, genetic engineers, agronomists, and soil scientists are therefore challenged to develop more drought tolerant hybrids or identify alternative management practices (supplemental irrigation) that will mitigate water stress and increase seed yield of Cuphea.
Technical Abstract: Cuphea is a potential new crop enriched in medium-chain fatty acids (MCFA) that are used to manufacture personal care and nutritional products. Although domestication began a decade ago and most species thrive in tropical environments, little is known about the adaptation of and best agricultural management practices for Cuphea. A field study was initiated in western Minnesota to determine the impact of sowing date and row spacing on soil water use and rooting characteristics of Cuphea. Cuphea was sown on 4, 18, and 30 May 2001 and 30 April, 14 May, and 28 May 2002 in rows 200, 400, and 600 mm apart. Water use was assessed by measuring rainfall, soil water content, and water flux below the root zone. Root length density was determined at the onset of seed fill. Aboveground biomass, seed yield, and water use were increased by sowing Cuphea in late April or early May rather than in late May. Sowing date also influenced water-use efficiency (WUE), but only in 2002. Sowing earlier in the spring also increased root growth as root length density in the upper 0.2 m of the soil profile. Row spacing did not affect seed yield, water use, or root length. This study suggests that biomass, seed yield, water use, and root growth of Cuphea are favored by sowing early in the spring. Although water use was accentuated by sowing early, a tendency existed for Cuphea to utilize water more efficiently in seed production when sown earlier in the spring.