Respiration of Leaves During Photosynthesis III. Respiration Rate and Mesophyll Resistance in Turgid Cotton Leaves, with Stomatal Control Eliminated

Abstract

Mixtures of carbon dioxide in air, nitrogen, or 1 % oxygen in nitrogen, prepared beforehand in plastic balloons, were passed through illuminated cotton leaves in a laboratory leaf chamber. This procedure enabled much more accurate calculation of intercellular carbon dioxide concentration than conventional gas flow techniques. It also made it possible to calculate leaf temperature from a measurement of the vapour pressure of the air leaving the chamber. From the measured flow rates and changes in the carbon dioxide concentration of the gas mixtures, the relation between the net rate of carbon dioxide exchange and the intercellular carbon dioxide concentration was calculated.