Generation Mechanisms of Bark Split Frost Injury of Tea Plant by the Artificial Freezing Treatment

Abstract

Bark split frost injury of tea plant occurs to young trees in early winter and early spring. If the damage is severe, the tea plant can wither and die. This led us to investigate the mechanism of bark split frost injury. Bark splitting caused by the formation of ice, was observed near the cambium layer of tea branch within 2cm above the surface of rock wool fully absorbed with water, when treated at -5°C. Bark splitting was not observed when the tea branches were inserted into dry rock wool. These facts indicate that bark split frost injury is caused by water. Liquid leaks were observed at several places of tea branches when the temperature was returned from -5 °C to room temperature. This phenomenon is possibly involved in bark split frost injury of tea plant. Although a split in cortex at the part of damage was confirmed with MRI, the blockage of sap-flow could not be confirmed.