Abstract
The freezing method is most effective for frost protection in tea production; however, preparation of enough water for application has been difficult. Recently, Zero-control, a new water-saving-type sprinkler system that helps maintain the tea canopy temperature above its critical temperature by controlling water application via a temperature sensor, has been developed. In this study, we report the establishment and extension of Zero-control adapted to a 100-second rotation application system popular in the Soo region of Kagoshima Prefecture. In the test tea field, Zero-control maintained the tea canopy temperature above -1℃ after freezing, and no frost damage was observed in the spring of 2011, which had frequent hard frost. In addition, water consumption by Zero-control was 57% less than that by the 100-second rotation application system. For the use of Zero-control, both sensitivity and setting location of the temperature sensor of the system are important, especially in tea fields that have a temperature gradient. Because it has been proven that Zero-control can protect tea shoots from frost damage and save water effectively, many tea farmers have introduced Zero-control in their sprinkler systems. We taught practical use of Zero-control to tea farmers. After water application using Zero-control was started in the autumn of 2011, shortage of water supply and frost damage of tea shoots have not occurred.
