Air temperatures in agriculture greenhouses may become too high in summer season for cultivating some plants. So we investigated the effects on tomato plant yield of a groundwater cooling system for the inhibition of temperature rise under high temperature conditions in a tomato cultivation plastic house. The tests were carried out from June to August 2016, in the site of Ishikawa Prefectural Agricultural Experiment Station. The air temperature and OT (Operative Temperature) were reduced and a remarkable cooling effect was acquired with the groundwater cooling system. However, the subject remained about saturation deficit condition.
