The effects of Zinc, Caffeine and NaCl on olive and tomato physiology and metabolism

The aim of the research was to evaluate the accumulation of certain organic and inorganic chemicals on plants, focusing on olive and tomato fruits, given the importance of these cultivars in the Mediterranean area. The responses of olive trees to caffeine (Annex I) and NaCl (Annex III) were tested. Olive plants cv Leccino were treated with caffeine (0.14 µg L-1), while in the third experiment the effects of NaCl (100 mM) on Leccino, Frantoio and Leccino grafted on Frantoio were studied. Tomato plants (Annex II) were exposed to treatments with caffeine (1 mg L-1) and Zn (1 mM Zn) to evaluate possible effects on tomato fruit yield and quality. The accumulation of the caffeine and polyphenol profile in the plant organs was evaluated by LC-MS/MS analysis. Heavy metals and micro and macro elements were measured by MP-AES analysis. Fruit ripening index and plant growth parameters (shoot length, number of leaves and fruits, and plant biomass) were monitored in all experiments. Olive gas exchange (CIRAS 2), chlorophyll a fluorescence (FMS2) and SPAD parameters were monitored during the experiments. Tomato quality was tested by Brix and ethylene production was measured by gas chromatography.