ARS | Publication request: CUPHEA SEED YIELD, BUT NOT SEED OIL CONTENT IS REDUCED BY DROUGHT

Submitted to: Meeting Abstract
Publication Type: Abstract
Publication Acceptance Date: September 22, 2004
Publication Date: September 22, 2004
Citation: Gesch, R.W., Sharratt, B.S., Cermak, S.C. 2004. Cuphea seed yield, but not seed oil content is reduced by drought [abstract]. Association for the Advancement of Industrial Crops. p. 38.

Technical Abstract: Cuphea can potentially serve as a domestic oil replacement for small and medium-chain fatty acids used in chemical manufacturing. Present domesticated lines of cuphea (Cuphea viscosissima Jacq. x C. lanceolata f. Silenoides W.T. Aiton) grow exceptionally well in the upper Midwest. However, cuphea does not have a deep root system, is not an efficient water user, and therefore, may be susceptible to drought stress. A field study was conducted in west central Minnesota in 2002 and 2003 to assess cuphea seed yield and seed characteristics under non-limiting soil moisture conditions. In both years, two levels of irrigation were compared to a non-irrigated control treatment. Drip irrigation was used to maintain soil moisture to field capacity (soil matric potential ~ 0.3 bar) for the fully irrigated treatment and at 50% of the available water-holding capacity of the soil (soil matric potential ~ 0.7 bar) for the partially irrigated treatment at a 30 cm wetting depth. In 2003, drought conditions were experienced from mid July throughout August. During this time, cuphea was flowering and setting seed. Between July 10 and September 9, only 3.2 cm of rain was received at the experiment site. Severe drought stress symptoms, including dramatically reduced leaf water potential and photosynthetic rates, were observed during late summer for non-irrigated plants. Seed yield of fully irrigated plants was over 2.5 fold greater than that of the controls. However, biomass production was not as dramatically affected and seed oil content was similar across treatments at about 34% (w/w). Results indicate that cuphea seed production, but not seed oil content is sensitive to drought. Likely, severe drought stress as observed in 2003 was partially due to poorly developed roots inherent to present domesticated lines of cuphea. Future, wide-spread regional success of cuphea may depend on genetic improvement of drought tolerance.