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Change in the pattern of photosynthetic response to temperature in wheat leaves in winter

Jiang Hua, Shi Shengbo, Xu Daquan

Shanghai Institute of Plant Physiology,Chinese Academy of Sciences.Shanghai 200032；China

Abstract

There were two patterns of the response of net photosynthetic rate (Pn) to temperature in detached leaves of wheat grown in the field in winter. One pattern was observed at the beginning of December. After the air temperature around leaves was shifted from 10deg C to 30deg C by 5deg C steps, Pn increased gradually with time at 30deg C. And when the air temperature was decreased by the same steps to 10deg C, the values of Pn were higher than those measured at the same temperatures during the process of increasing temperature. The first pattern probably originates from an enhancement of the activities of some enzymes involved in the photosynthetic carbon assimilation, as shown by both the decrease of intercellular CO_(2) concentration (Ci) and the increase in phosphate content (Pi) in detached leave at 30deg C. Another pattern was observed after the middle of December. In contrast to the first pattern, Pn decreased gradually with time at 30deg C and the values of Pn measured in the subsequent process of lowering temperature were lower than those measured at the same temperature in the process of increasing temperature. The increases in both Ci and the membrane permeability observed at 30deg C indicate that the second pattern is likely a result of injury caused by high temperature to the membrane system of the photosynthetic apparatus acclimated to low temperatures in winter.

Key words: Net photosynthetic rate;Acclimation to low temperature;Response to temperature;Intercellular CO_(2) concentration;Phosphate limitation;Membrane permeability;Wheat

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Citing This Article：

Jiang Hua, Shi Shengbo, Xu Daquan. Change in the pattern of photosynthetic response to temperature in wheat leaves in winter. Acta Physiol Sin 2000; 52 (1): (in Chinese with English abstract).