EFFECT OF CARBON-DIOXIDE ENRICHMENT DURING IN-VITRO CULTIVATION AND ACCLIMATION TO EX-VITRO CONDITIONS

Tobacco and carnation plantlets were grown in vitro on Murashige and S koog's medium with 2% saccharose. Carnation plantlets were also grown fully photoautotrophically on a medium without saccharose. The ambient CO2 concentration was increased from 0.6 to 10 or 40 g m(-3) during t he last 3 weeks of in vitro cultivation or during the first 3 weeks of acclimation to ex vitro condition (plantlets transplanted to pots wit h sand and nutrient solution) or during both growth phases. CO2 enrich ment during in vitro cultivation markedly stimulated growth of tobacco plantlets, and also of carnation plantlets, both with and without sac charose. CO2 enrichment during the acclimation period promoted plant g rowth more effectively in plantlets grown in vitro at a CO2 concentrat ion of 0.6 g m(-3) than in plantlets grown in either growth phase at h igher CO2 concentrations.