CO2Compensation Concentration, Rate of Photosynthesis, and Carbonic Anhydrase Activity of Plants

Abstract

Leaves of a number of plant species were surveyed for their CO2compensation concentration which is one of the distinguishing characteristics used to classify plants on the basis of their photosynthetic capacity. Monocot genera with low CO2compensation values are mainly limited to tribes of Chlorideae, Paniceae, Andropogoneae, Tripsaceae, and a part of Festuceae in Gramineae. Major grain crops, except corn (Zea maysL.) and sorghum (Sorghum vulgarePers.), are primarily in the tribes of Hordeae, Aveneae, and Oryzeae, and have high CO2compensation concentrations. Seven genera of dicots with low CO2compensation occur in the four families of Amaranthaceae, Chenopodiaceae, Portulacaceae, and Euphorbiaceae. Major dicot crops are in the families Leguminosae and Malvaceae and have high CO2compensation points. Low CO2compensation concentration also is correlated with low carbonic anhydrase activity. Conversely, high CO2compensation concentration plants have a high carbonic anhydrase activity. Data on the influence of light intensity and temperature on the rate of photosynthetic CO2fixation in leaves from plants with high and low CO2compensation concentration indicate differential responses of photosynthesis to these environmental factors. The data are interpreted as supporting a hypothesis for competition by specific plants.