Studies on Matter Production in Wheat Plant

V. The mechanism involved in an after-effect of low night temperature

Abstract

Using potted wheat seedlings, the authors attempted to determine the mechanism of depression in apparent photosynthesis brought about as an after-effect of low night temperature. From the results obtained it was inferred: that the depression of apparent photosynthesis brought about as an after-effect of low night temperature is attributable not to the acceleration of photorespiration, but to the depression of photosynthesis itself, that the photosynthetic depression mentioned above is caused by both decreases in the stomatal aperture and the photosynthetic activity within mesophyll cells, and that the decrease in the photosynthetic activity within mesophyll cells is caused, at least in part, by a decrease in the activity of light reaction. However, the decrease in the photosynthetic activity was not always associated with a decrease in the activity of dark reaction.