Sulfate accumulation and calcium balance in hydroponic tomato culture

Sulfate accumulation may reduce calcium (Ca) activity in solution. The objective of this study was to relate solution and foliar nutrients for greenhouse tomato (Lycopersicon esculentum Mill. cv 'Trust') receiving nutrient solutions enriched with 0.1, 5.2, 10.4, or 20.8 mM of sulfate. Solution components were expressed as crude or free concentrations, which were row-centered log ratioed (RCLR). As an expression for nutrient balance, RCLR adjusts any nutrient value to the geometric mean of all nutrient levels. Solution and foliar datasets were related to each other using canonical correlations. RCLR produced greatest redundancy between the two datasets (R-2 = 0.640-0.654), and raw data, the smallest (R-2 = 0.498-0.513). Canonical analysis of RCLR-transformed free concentrations indicated a dominant sulfate effect and significant secondary effects clue to adjustment of the anion-cation balance in solution. Free sulfate concentration as RCLR explained 66% of the variation in foliar sulfur (S) and 71% of the variation in foliar Ca. The RCLR transformation should be further examined in relation with Ca imbalance and interactions in fruit crops.