Potential of Organically-Sourced Fulvic Acid to Increase Bioavailability of Calcium in Hydroponic Lettuce (Lactuca sativa) and Reduce Tip Necrosis

Fulvic acid may reduce tip necrosis in the Salanova® Red Gem lettuce cultivar, often caused by calcium deficiency. We treated lettuce with Hoagland’s fertilizer and FA in a full factorial experiment, hypothesizing FA-treated groups would increase calcium concentration and reduce tip necrosis. Response variables of tissue calcium concentration and tip necrosis percentage were analyzed using multifactor ANOVA and regression. Tissue calcium concentration was measured using the Dumas Method and ICAP. FA increased calcium uptake (P = 0.03) yet did not reduce tip necrosis (P = 0.94). Other factors beyond calcium uptake likely contributed to tip necrosis, notable for future research.