Water Spinach (Ipomoea aquatica) is a novel crop within the U.S. that is widely grown throughout southeast Asia. Although considered a noxious weed by USDA, interest from ethnic communities has led to the restricted permittance of cultivation within Georgia, USA. In order to determine nutrient requirements for hydroponic production of water spinach, a study was conducted using a deep-water culture in a greenhouse located in Watkinsville, Georgia, USA in the summer of 2023. Two selections of water spinach were grown in plastic containers filled either a ¼ or ½ strength Hoagland’s solution arranged in a randomized complete block design with four replications of each selection by nutrient solution combination. Initially, 15 plants of each selection were placed into the tubs. Beginning at 21 days after transplanting, two plants were removed from each tub for determination of biomass and nutrient concentrations. Additional plants were removed at 10-day intervals until a final harvest at 61 days after planting. The trial was then repeated. Results indicated that biomass (root and shoot) and nutrient removal within foliar tissues were significantly greater in the ½ strength solution compared to the ¼ strength solution. Total nutrient accumulation for most macronutrients exhibited a quadratic response, increasing until 51 days after planting and then plateauing. Plants grown in the ½ strength and ¼ strength Hoagland’s solution accumulated similar concentrations of foliar macronutrients though due to differences in biomass accumulation, total nutrient removal was significantly different between the two nutrient solutions. At harvest (day 61), ½ strength plants had an average potassium (K) concentration of 5.24% (dry weight), while those grown in the ¼-strength Hoagland’s solution averaged 4.48% K on a dry weight basis. However, due to significant differences in biomass production, K nutrient removal rates were more than twice as much in the plants grown in the ½ strength Hoagland’s solution compared to those grown in the ¼ strength solution. Our results suggest that although water spinach may grow in river systems in its native environments, that growth benefits from additional levels of fertilizer nutrients when cultivated in greenhouse systems and that a ½ strength Hoagland’s solution should be an appropriate baseline to develop recommendations for hydroponic nutrient solutions for greenhouse production of water spinach.
