Abstract
On the preventing frost damage of the tea bush by thin straw mat covering the warm keeping effect was compared between two methods, one was putting the mat on the bush surface (direct covering), the other was holding the mat 60 cm. apart from the bush (indirect covering), the former of these frequently could not prevent severe damage. The air and leaf temperature under the either covering method were kept higher than that in the open plot, especially those under the indirect covering were much higher. The straw mat covering was more effective on a calm night than on a windy one. The difference of air temperature between direct covering and open plot was small, as the bush under the covering was influenced by the radiate cooling from the colder covering material. The leaf temperature under the covering was kept higher than open one, but the touched leaf to the covering material was colder than that of the untouched. These fact suggested that the cold mat more influenced on the air and leaf temperature owing to its nearer situation, and the touched leaf was cooled by heat conduction from colder covering material.
