Impact of Exogenous Melatonin on Fruit Quality and Storability of Tomato (Solanum lycopersicum L.)

our study revealed the beneficial effect of melatonin, an indole amine hormone, on food value and storability of tomato. We have taken four doses of melatonin viz. 50, 100, 250 and 500 µmol/L. Two sprays were done at fruit setting and color break stage. Application of melatonin @ 250 µmol/L was found to be advantageous in improving the carbohydrate, protein, fat, total sugar and total soluble solids content in tomato fruits as compared to control (without melatonin). Melatonin application @ 250 µmol/L showed reduced activity of polygalacturonase-I (37.16%), polygalacturonase-II (39.40%) and ascorbic acid oxidase (35.14%) as compared to control; whereas maximum reduction of polyphenol oxidase activity (28.03%) was associated with melatonin (500 µmol/L). Melatonin application on phenolics, flavonoids, ascorbic acid and antiradical activity in tomato also shown interesting results. Overall, exogenous application of melatonin @ 50 to 100 µmol/L was found to be beneficial for higher bioactivity in tomato in terms of lycopene content (15.56 ± 0.99 mg/kg of tissue), total phenolics (27.8 mg GAE/100 g), L-ascorbic acid (28.45±2.51 mg/100 g) and DPPH radical scavenging activity (12.80 mg AAE/100 g). Total flavonoids content was found to be highest (3.30 mg QE/100 g) with melatonin @ 250 µmol/L.  Moreover, application of Melatonin (250 µmol/L) increased the shelf life up to 25 days as compared to 15 days under control at room temperature. The findings clearly suggest that application of exogenous melatonin is a potential option for enhancing food value and storability of tomato.