Abstract
Photosynthesis of bean leaves (Phaseolus vulgaris var. Bountiful) was markedly decreased by temperatures below 20[degree]. When the roots of the plants were watered daily with 10-3 [image] decenylsuccinic acid, no decrease in photosynthesis was observed from 25[degree] to 5[degree]. An analysis of the resistances to transport of CO2 was made, and the effect of the treatment is explained as an induced increase in carbon dioxide permeability of the plasma membranes of the mesophyll cells.