Acclimation of Young <i>Doritaenopsis</i> Queen Beer‘Mantefon’Plants under Increased CO<sub>2</sub> Concentration

Abstract

This study was conducted to investigate the CO2 exchange rate and growth characteristics of young Doritaenopsis plants acclimated to increased CO2 concentrations. Six-week-old clones of Doritaenopsis Queen Beer ‘Mantefon’ were grown for 27 weeks in four controlled-environment growth chambers maintained at 400 ± 100, 900 ± 100, 1500 ± 100, or 2100 ± 100 μmol CO2·mol-1 during the dark period. The highest CO2 uptake of the uppermost mature leaf, which existed before treatment, was observed in the 900 μmol CO2·mol-1 treatment, followed by the 2100, 1500, and 400 μmol CO2·mol-1 treatments. However, after CO2 treatment, plants acclimated at 2100 μmol CO2·mol-1 showed the highest CO2 uptake in the first newly developed mature leaf, and the amount of CO2 absorbed increased with increasing CO2 treatments. Leaf length and width of the uppermost mature leaf and total biomass decreased in the 900, 1500, and 2100 μmol CO2·mol-1 treatments, whereas new leaf development was significantly promoted under elevated CO2 conditions. These results indicate that acclimation to increased CO2 concentrations can enhance the CO2 uptake and development of new leaves in young Doritaenopsis plants, but leaf growth and biomass accumulation might decrease at concentrations over 900 μmol CO2·mol-1. Therefore, we recommend further research to investigate the effects of acclimation to high concentrations of CO2 on Doritaenopsis plants.