CO₂ enrichment with light control improves photosynthetic response and flower quality in Phalaenopsis Queen Beer 'Mantefon'

Phalaenopsis are easy to market as they are valued commercially worldwide. CO₂ supply has the potential of enhancing plant growth rate, shortening the growth period, and reducing energy costs associated with plant production. We investigated the flowering and photosynthetic responses of Phalaenopsis Queen Beer 'Mantefon' to CO₂ enrichment and light level. Potted plants at the flowering stage were supplied with low light intensity (LL; 90±10 μmol m^‑2 s^‑1) or high light intensity (HL; 260±40 μmol m^‑2 s^‑1) and different levels of CO₂. CO₂ was supplied to the plants, which perform CAM metabolism, during their dark period at three concentrations: 400 (control), 800, and 1200 μmol mol^‑1 CO₂. Net CO₂ assimilation rate (P_n) of leaves of 1200 μmol mol^‑1 CO₂ was higher than those grown under 400 μmol mol^‑1 CO₂ grown under HL at 8 and 12 weeks after treatment. Flower spike length elongated more in the plants of 1200 μmol mol^‑1 CO₂ under HL than those under LL. Flower bud production fastened most in the plants of 1200 μmol mol^‑1 CO₂ under HL. The number of flowers was highest in the plants of 800 and 1200 μmol mol^‑1 CO₂ under HL among the other treated plants. We conclude that photosynthesis is enhanced in CO₂-enriched plants and flower quality is maximized at CO₂-enriched with high light intensity combined condition in Phalaenopsis.