Water Resources Research Act Program

Principal Investigators: Ramon Arancibia, Donald Bailey

Abstract: In spite of the favorable conditions to grow horticultural crops throughout the year in the U.S. Virgin Islands (USVI), production is restricted because of water deficit. This is particularly noticeable during the dry season (December to August) when evaporation is higher than rainfall. Heavy rains in the USVI are concentrated in the wet season (September to November) and the average rainfall in St Croix is 1041 mm per year which corresponds to 60% of the pan evaporation. This water deficit can be ameliorated in the horticulture industry by growing crops under shady conditions. Plants require substantially less water (40% to 60%) because of reduced evapo-transpiration under shade conditions. In addition, many tropical high value ornamentals perform better in shady conditions. This project proposes to develop a water budget for shade-house production of ornamentals. The specific objectives of this study are: a) to determine the optimal WP of anthuriums by quantifying the shading effect on crop evapo-transpiration (ETc), growth and flower production; b) to determine the crop coefficients that associates ETc under shade with pan evaporation and potential evapo-transpiration (ETo); c) to estimate irrigation water requirement throughout the year for anthurium cut flower production under optimal shade conditions. A greenhouse with three shading levels (treatments) will be used for this study. Potted anthurium, a tropical ornamental cut flower, will be grown under each treatment and monitored for soil moisture and water used. ETc, plant growth and cut flower yield will be evaluated to determine the shading condition for optimal water productivity and water requirements. Climatic data (rain, relative humidity, pan evaporation, light intensity, temperature, etc) from a weather station will be analyzed to determine ETo. Water requirements under optimal growing conditions will be associated with ETo and pan evaporation to determine crop coefficients. The information obtained in this project will help horticulturists in the USVI develop decision criteria for crop selection and adoption of a water-sustainable production system.