Changes in Leaf Water Potential, Lethal Temperature and Carbohydrate Content of Wintergreen (Pyrola japonica Klenze) during Overwintering

越冬 중 노루발의 水分포텐셜, 致死溫度 및 炭水化物量의 變化

Changes in water potential, lethal temperature and carbohydrate content in the leaves of wintergreen (Pyrola japonica) during overwintering were investigated. Leaf water potential was kept at -2 bars in the tender stage before October, decreased to -46 bars in the dormancy stage and increased to -2 bars again after dehardening Lethal temperatures of the leaf tissue were $-7^{\circ}C$ in the tender stage and $-7^{\circ}C$ in the dormancy stage, but did not recover up to that of the tender stage during dehardeding. Peak of soluble sugar content coincided with the nadir of the leaf water potential. There were close relationships among daily minimum air-temperature, leaf water potential and lethal temperature in changing patterns during overwintering.