A Mobile Apparatus for Measuring Leaf Photosynthesis in the Field

Abstract

An apparatus is described that has been designed to measure the gas exchange of individual cereal leaves in the field, using infrared gas analysis. Measurements on leaves of winter wheat showed that there was true saturation of net photosynthesis at high irradiances but as irradiance decreased there was a proportional decrease in net photosynthesis. Measurements made on wheat plants grown in a controlled environment, for comparison, showed the photosynthesis–light response curve to be better fitted by a rectangular hyperbola. This dissimilar response of photosynthesis to irradiancc for plants grown in controlled environments indicates the possible problems of extrapolation from the laboratory to the field.