Effect of Water Deficit on Photosynthesis and Tuber Metabolism in Potatoes

The primary effect of a period of drought on potato plants was to reduce the rate of photosynthesis. Decreases in CO2 uptake could mainly be ascribed to an increase in the residual resistance to CO2 transport. Levels of sugars and of starch-synthesizing enzymes in extracts from tubers of droughted and control plants were similar, and it is likely therefore that the effect of drought on tuber growth is exerted mainly via a reduction in the supply of assimilate.