A regime of high CO2 concentration improves the acclimatization process and increases plant quality and survival

A change in the environmental conditions through CO2 enrichment was used to improve acclimatization of Cynara scolymus tissue-cultured plants. Plants were transferred from tissue culture conditions to a climatic chamber, where the acclimatization was carried out at 800 mu mol mol(-1) CO2 and at the ambient CO2. The experiment lasted 3 weeks and physiological measurements-such as plant water status and growth, electrolyte leakage, net CO2 assimilation, internal CO2, stomatal conductance, transpiration, chlorophyll fluorescence, free amino acids, photosynthetic pigments and lipid peroxidation-were taken every 4 days. During the experiment plants cultured under CO2 enrichment exhibited earlier stomatal control and a rapid increase in the photosynthetic rates. As a result, the water potential increased rapidly and the relative water content and the water use efficiency were higher than in plants cultured at ambient CO2. At the end of the experiment the plant survival was completely successful under the elevated CO2, which enhanced the acclimatization process-diminishing plant mortality through attenuation of plant damage and allowing better adaptation of plants to the environmental conditions.