Submitted to: Industrial Crops and Products
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 27, 2004
Publication Date: March 1, 2005
Citation: Olness, A.E., Gesch, R.W., Forcella, F., Archer, D.W., Rinke, J.L. 2005. Importance of vanadium and nutrient ionic ratios on the development of hydroponically grown cuphea. Industrial Crops and Products. 21:165-171. Interpretive Summary: Cuphea is a potential new or alternative crop that shows promise for production of low molecular weight oils. Almost nothing is known about the nutritional needs and responses of cuphea to fertilizers. A growth chamber study was conducted to test the ability of cuphea to resist effects of vanadium, an element common in soils that is very toxic to most plants. Vanadium and magnesium sulfate levels were varied in hydroponic cultures of individual cuphea plants for 28 days. Plants were evaluated for total growth, relative root growth, root area, root length, total above ground leaf and stem growth and chlorosis resistance. Results show cuphea is very sensitive to vanadium and that additions of magnesium sulfate increased the sensitivity to vanadium. Without vanadium, the additions of magnesium sulfate enhanced growth by about 20%. Attempts to produce cuphea commercially should avoid sites rich in readily available vanadium. Sites with little vanadium but rich in magnesium should produce superior yields. Future commercial producers will benefit from this research through the identification of the critical nutrient relationship that inhibits cuphea production.
Technical Abstract: Cuphea seed contains oils that have industrial application. However, little is known regarding its optimal mineral nutritional requirements or responses to inhibiting elements. Oil seed crops often need additional phosphorus (P) to achieve optimal economic yield. Vanadium (V), a commonly occurring soil constituent, interferes with plant P uptake and earlier work showed that V is a factor in lipid metabolism. Hydroponic culture was used to evaluate the relative effect of V on growth and development of cuphea (Cuphea viscossisima x C. lanceolata 'PSR 23'). Relative root length, root surface area, root weight, and aerial dry weights decreased exponentially as rates of the V concentration increased from 0 to 153 uM. In contrast to field observations of other crops, additions of MgSO4 to increase the Mg:(Mg + Ca) ratio further decreased plant growth by as much 50% at V concentrations greater than 31 uM. Root length decreased by about 50% of the control when grown in 153 uM V and relative root area and dry weight decreased by > 75%. Increases in V concentration sharply reduced secondary and higher order lateral branching. Reduction in root growth was accompanied by a general chlorotic appearance. The results suggest that readily available V in field situations will result in poor root growth and crop performance of cuphea. Also, the interaction of V and MgSO4, common in soils in the region, will lead to further reductions in yields in the field.