Experimental Investigation of Ice Formation on Tea Leaves for Sprinkler Frost Protection

Sprinkler irrigation is an effective method to protect tea buds and leaves from frost injury. This study was conducted to investigate the freezing process of sprinkler irrigation water on leaves of tea cultivar “Zhongcha 108” under radiation frost events. The retention ice formation was observed in simulated experiments using a fluorescence tracer method. In field sprinkler irrigation experiments, the dimensions of the retained ice were measured, and the effects of ambient temperature and control mode on ice dimensions were analyzed. The main findings are as follows: Firstly, the retained ice on leaves consists of a leaf-surface ice layer and a cylindrical leaf-tip icicle. Secondly, both the ice layer thickness and the icicle length increase linearly with decreasing ambient temperature. Thirdly, the intermittent sprinkler irrigation significantly affected the dimensions of the retained ice: water consumption was cut by 50%, with the ice layer thickness and icicle length decreasing by 39.2% and 23.4%, respectively. These findings advance our understanding of sprinkler frost protection and provide a theoretical basis for predicting retained-ice quantities.