Nutraceutical quality of grafted tomato and cultivated in the NFT system

ABSTRACT Malnutrition problems are related with diets lacking one or more essential elements, which are extremely important for food enrichment to improve the content of compounds effective for health. The objective of this study is to evaluate the effect of the addition of Ca2+, K+ and Mg2+ on the induction of nutraceutical quality in grafted tomatoes grown in the NFT (Nutrient Film Technique) system. In the experiment, two factors were evaluated: plants with and without grafting and the foliar application of 10 mL/L Ca2+, 4 mL/L K+ and 10 mL/L Mg2+ cations separately for each case, in addition to the control (grafted and non-grafted plants without foliar applications). The treatments were evaluated using a completely randomized design, with 5 repetitions per treatment. The interactive effects between grafting and foliar application of Ca2+ induced a greater content of lycopene, β-carotene and total flavonoids in tomato fruits. The interactive effects between the graft and the Mg2+ foliar applications obtained the best results in the phenol content. About the antioxidant capacity of 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′ -Azino-bis-[3-ethylbenzothiazoline-6-sulfonic acid (ABTS)], the graft decreased the concentration, increasing the content of these through foliar applications of calcium. Regarding the enzymatic variables, graft factor increased the activity of catalase, glutathione peroxidase and phenylalanine ammonium lyase and obtained the best results of graft interaction and foliar application of calcium and magnesium. The foliar application of K obtained a low response on antioxidant defense systems. The obtained results demonstrate the influence of grafts and foliar applications of calcium and magnesium as tools that could improve the nutraceutical quality of tomato.