Effects of Varying Sulfate Concentrations on Growth and Mineral Nutrition of the Greenhouse Tomato

Abstract

In hydroponic recirculating systems, sulfate ions can accumulate to excessive levels and interfere with other nutrient ions. The objective of this research was to determine the effects of four sulfate concentrations on growth and mineral nutrition of greenhouse tomato plants (Lycopersicon esculentum Mill. cv. Trust). Tomato seeds were sown in flats and subsequently transplanted into rockwool slabs. Ten days after transplanting, plants were given four sulfate concentrations in nutrient solutions (S0 = 0.1, S1 = 5.2, S2 = 10.4, and S4 = 20.8 mM). The plots were arranged in a randomized complete-block design with four replications. Treatment S0 reduced dry weight of the top portion of the plant. A sulfate shortage in the nutrient solution decreased S concentrations in the leaf and decreased fruit number. Activities and concentrations of major ions in solutions expressed in mM or as row-centered logratios were correlated with corresponding foliar concentrations expressed in grams of nutrient per kilogram of dry matter or as row-centered logratios. Data were presented in this manner in order to explore interactive models describing relationships between mineral composition of both nutrient solutions and plant tissues. High concentrations of sulfate ions in the nutrient solution up to 20.8 mM did not affect tomato growth or yield. Tomato plants appeared prone to sulfate deficiency, but tolerant to sulfate concentrations up to 20.8 mM in the nutrient solution.