Winter-depression of Photosynthesis in Tea Plants with Special Reference to Cultivar and Leaf Age.

Abstract

Winter-depression of photosynthesis in overwintering leaves of tea (Camellia sinensis (L.) O. Kuntze) plants was investigated with special reference to cultivar and leaf age. Photosynthetic activity of the leaves was measured with an oxygen electrode. In cold-resistant cultivars 'Yamatomidori' and 'Yabukita', depression of leaf photosynthesis in winter was relatively slight and recovered of the activity in early spring progressed favorably. Conversely, winter-depression of photosynthesis was severe in the cold-sensitive cultivar 'Inzatsu-131', and the recovery in spring was slight. Less cold-sensitive cultivar 'Benihikari' showed the intermediate response to low temperature between these two groups. Thus, there was a close relationship between the degree of depression of photosynthesis during winter and the extent of cold-resistance among the four cultivars examined. As the late-sprouting immature leaves showed marked depression of photosynthesis in winter, photosynthetic activity during winter was compared among leaves with different leaf ages. Maximum activity before the winter cold was highest in the fourth crop leaves which were most recently matured, followed by the third and the second crop leaves. Under winter cold, however, photosynthetic activities were equally depressed by 40% in leaves of all ages, indicating that the depression of photosynthesis was not affected by the leaf age. These results suggest that fully mature tea leaves with different ages would have same susceptibility to low temperature stress.