Effects of root cooling on fruit quality of cocktail tomato

Modern horticulture systems rely on the ability to alter microclimate components surrounding crops, such as temperature and light, to improve yield and quality of products. Root temperature has also long been considered as an important ecological factor that determines a variety of structural and functional characteristics. However, little is known about the effect of root temperature on food quality of horticultural crops. Cocktail tomato, as the hybrid of cherry tomato with normal sized tomato, is getting increasingly popular among the consumers, due to its suitable size. Additionally, cocktail tomatoes contain higher level of rotenoids and other antioxidants than normal sized ones. The effects of root temperature on fruit quality (sensorial attributes and nutritional components) were examined in two cocktail tomato varieties “Amoroso” and “Delioso” during the winter of 2017-2018. Plants were grown hydroponically on rockwool with varied root temperature (16-24°C and 10°C) from inflorescence to harvest inside the greenhouse. Root emperature 10°C was manipulated independently from air temperature (16-29°C) by circulating cooling water. Reductions of total and marketable yield per plant in both varieties were observed in response to root cooling by 7.7-17.9% and 7.9-20.9%, respectively. Glucose and fructose concentration increased by 7.8-16.1% and 7.4-14.0% with the application of root cooling. Lycopene concentration increased 15.9% in “Delioso”, β-Carotene increased 10% in “Amoroso” and ascorbic acid concentration increased 21 % in “Delioso”. Besides, N, K, S, Fe concentration reduced by 6.8-18.1% in “Delioso”, whereas no statistical changes in elements concentration were observed in “Amoroso”. Thus, manipulation of root temperature could be a feasible method to improve overall fruit quality of cocktail tomato