NaCl-induzierter crassulaceen-Säurestoffwechsel bei der salzpflanze Mesembryanthemum crystallinum : Abhängigkeit des CO2-gaswechsels von der Tag/Nacht-temperatur und von der wasserversorgung der pflanzen

Abstract

The halophytic species Mesembryanthemum crystallinum was induced to exhibit CAM-like CO₂ gas-exchange reactions with a depression of net CO₂ uptake during the day and a net CO₂ uptake during the night by treatment with 400 mM NaCl. The induction of CAM is favored by relatively high day temperatures and relatively low night temperatures. Net CO₂ uptake in the dark is largely increased by an interruption of water absorption by the plants, whereas light CO₂ fixation is decreased by this treatment. When plants are rewatered after a two days drought period, net CO₂ uptake in the dark is clearly favored over CO₂ light fixation. During the post-stress period a slight reduction of leaf chlorophyll content becomes apparent. Under the experimental conditions used a reversibility of CO₂ fixation metabolism from CAM to C₃ is observed when salt-treated plants are transferred to non-saline root medium. This is paralleled by a largely enhanced leaf expansion and a drastically increased leaf water content.