Calcium deficiency - Influence on the antioxidative defense system in tomato plants

In this study the influence of a deficient calcium supply on the antioxidative defense system in Lycopersicon lycopersicum leaves was investigated. Trials were performed in the greenhouse employing soilless culture technique. For the induction of calcium deficiency, calcium content in the nutrient solution was reduced from 2.9 mmol/L to 0.29 mmol/L. Within 6 weeks fruits and leaves developed distinct calcium deficiency symptoms. Chlorophyll fluorescence parameters, e.g. Fm and Fv/Fm, chlorophyll and tocopherol contents dropped below control level; also, superoxide dismutase activity was reduced. Additionally, malondialdehyde as a degradation product of lipid peroxidation increased in the calcium deficient leaves. Spray application of formulated CaCl2 solution on a weekly basis reduced blossom-end rot symptoms to about 50 percnt;. Furthermore, chlorophyll fluorescence parameters Fm and Fv/Fm as well as chlorophyll and tocopherol contents were less affected than in the calcium deficient group. No differences in malondialdehyde production could be established. SOD activity was higher in the Ca2+-treated leaves, while PO activity was lower compared to calcium deficient leaves.