Some Observations on Salinity-induced Crassulacean Acid Metabolism in Mesembryanthemum crystallinum: Effect of Ouabain

Abstract

Plants grown in uncovered pots and watered daily with either 350 mM KCl or NaCl showed a net uptake of CO₂ during the day followed by CO₂ release during the night, whereas plants grown under identical conditions, but in polyethylene-covered soil (covered pots) showed net CO₂ accumulation and acidification during the night phase (CAM expression). Spraying the tops of plants with 5 mM ouabain either induced CAM in the case of plants grown in uncovered pots or enhanced CAM in plants grown in covered pots. This effect of ouabain and some aspects of the gross ion relations of M. crystallinum are discussed.