THE PERMEABILITY OF NON-STOMATE LEAF EPIDERMIS TO CARBON DIOXIDE

Abstract

A leaf cup was sealed to the upper, non-stomate, surface of Hydrangea and Coleus leaves and radioactive CO2 at 1, 5 and 10% was passed through the cup for 4 hrs. The quantity of CO2 penetrating the epidermal layer was detd. by the use of a G. M. counter and by radioautographs. Expts. were conducted in the light and in the dark with the cup attached to the stomate and non-stomate surface. The degree of permeability of the upper epidermal layer of Hydrangea to CO2 was found to be proportional to the partial pressure of the gas above the epidermis. At 1% CO2, the amt. of CO2, gas penetrating the non-stomate epidermis of Coleus is equal to the amt. entering the leaf when the stomate side is exposed. The results indicate that light does not influence the permeability of the leaf epidermis to CO2.