Summer production of high soluble solid content tomato by the simple and low-cost nutriculture system in Hokkaido

Abstract

Tomatoes with Brix >8% are classified as high soluble solid content (SSC) fruits and are regarded as one of the more expensive vegetables in the Japanese market. These fruits are commonly produced by imposing some kind of stress, such as water stress (water deficit) or, salinity stress (high-level electrical conductivity) on plants. Summer is the off-season for high SSC tomatoes in the main production areas of Japan. These areas have a mild climate and they can experience high temperatures, therefore, inhibiting the ability to attain the precise stress controls needed for production of these valuable fruits. Hokkaido is the northernmost island of Japan and has a cool climate in summer. In this study, in order to explore the potential of establishing summer production of high SSC tomatoes in Hokkaido, we produced tomatoes using a simple and low cost nutriculture system with a nutrient solution containing sodium chloride (NaCl) in plastic greenhouses during 2013 and 2014. By applying 0-600 mL of nutrient solution adjusted to an electric conductivity (EC) of 3.0-4.0 dS m-1 to each plant cultivated in 21 cm diameter plastic pots every day, we were able to constantly harvest tomato fruits with Brix values higher than 8% from the 1st to the 5th truss throughout the experimental period in both years. Those with marketable yields (793 g plant-1 in 2013 and 611 g plant-1 in 2014) were sufficient for commercial production. These results suggest that it is possible to produce high SSC tomatoes in summer by using a simple and low-cost nutriculture system in a plastic greenhouse in Hokkaido.