Examination of a Water-saving Type Sprinkler System with a Variable Time-step Temperature-based Controller for the Protection of Tea Shoots from Frost

Abstract

SummaryIn order to reduce of the amount water used for protection of new shoots from frost,we examined a sprinkler system that could adjust the amount of water supply by choosing from several watering intervals depending on the surface temperature of tea plant canopy.When the temperature of new shoots was lower than the critical level, our sprinkler system continued to supply water, and when the temperature was higher than the critical level, our system reduced the amount of precipitation.In our study area, the temperature of new shoots was higher than the critical level, which was assumed to be -2.4 during 3 examination seasons (from 2005 to 2007). Further, compared to a fixed interval sprinkler system, our system was found to be more effective in protecting the shoots from frost and in conserving water.During the examination periods, the amount of water used by our system was about 40% of that used by the ordinary continuative sprinkler system, and it was about 80% of that used by the fixed interval sprinkler system.