CO2 Enrichment of Greenhouse Roses Affects Neither Rubisco Nor Carbonic Anhydrase Activities

The effect of prolonged CO 2 enrichment on the activities of ribulose l,5-bisphosphate carboxylase/oxygenase (Rubisco) and carbonic anhydrase (CA) of greenhouse roses were studied. Plants of Rosa × hybrids `Red Success' were grown for 2 years at ambient and 900 μl CO 2 /liter during winter and spring with 75 μmol·m -2 ·s -1 photosynthetically active radiation supplemental lighting for 2 years. Measurements of initial and Mg +2 -CO 2 -activated activities of Rubisco and CA were made during shoot development and at different positions within the plant canopy. Generally, there were no significant differences measured in the enzyme activities between the two CO 2 concentrations. The results suggest that the photosynthetic capacity did not change and that there were no characteristic adaptations to long-term growth (up to 20 weeks) at elevated CO 2 concentrations. The maintenance of Rubisco and CA activities with prolonged exposure to CO 2 -enriched atmospheres is proposed as the reason for long-term yield increases in roses when grown in enriched environments.