Applications of Abscisic Acid and Increasing Concentrations of Calcium Affect the Partitioning of Mineral Nutrients between Tomato Leaf and Fruit Tissue

This study examined how abscisic acid (ABA) and calcium (Ca) concentrations in nutrient solution affect concentrations of mineral nutrients in tomato leaves and fruit. Tomato plants were grown in a greenhouse at 25/20 °C (day/night) under a 16 h photoperiod. Plants were treated with different concentrations of ABA and Ca. Calcium was applied via the irrigation lines at 60, 90, or 180 mg·L−1. ABA was applied as a combination of foliar sprays and root applications. For foliar ABA applications, treatments consisted of deionized (DI) water control (0.0 mg·L−1 ABA) or 500 mg·L−1 ABA. For ABA root applications, treatments consisted of no ABA control (0.0 mg·L−1 ABA) or 50 mg·L−1 ABA applied via the irrigation lines. Results indicate that mineral nutrient concentrations in tomato leaf and fruit tissue varied in connection with each exogenous application of ABA. Variability in mineral nutrient concentration depended on if ABA was applied to the leaf or root tissue. Additionally, increasing Ca treatment concentrations either decreased or did not change mineral nutrients in tomato and fruit tissue. Thus, tomato plants react to acquiring mineral nutrients in numerous mechanisms and, depending on how the applications of exogenous ABA are applied, can have varying effects on these mechanisms.