Effects of artificial light intensity and ambient CO2 level on photosynthesis of Araceae Species commonly used for interior landscaping.

The photosynthetic light-response curves of Aglaonema commutatum ‘Sylver Queen’, Anthurium andreanum ‘Dakota’, Dieffenbachia picta ‘Camilla’, Philodendron erubescens ‘Red Emerald’, Spathiphyllum wallisi ‘Mauna Loa’, and Syngonium podophyllum ‘Maya Red’ plants were analyzed after a 3-month acclimatization period in a phytotron under 380-400 ppm CO2 concentration, 26 ± 2°C temperature and 8/16 hours of light/night (20 µmol m-2 s-1 by neon lamps). CO2 assimilation of completely expanded leaves, grown during the acclimatization period, was measured by infrared gas analyzer, increasing photosynthetically active radiation (photosynthetic photon flux density; PPFD) from 0 to 200 μmol m-2s-1 photon flux (common indoor conditions) and with two CO2 levels (400-800 ppm). Light compensation point (Lc; μmol m-2s-1), apparent quantum efficiency (AQE; μmol CO2 × μmol PPFD-1), respiration (Rd; μmol CO2 m-2 s-1) and photosynthesis rate at maximum PPFD (A200; μmol CO2 m-2 s-1) are discussed and used to classify species and define the suitable intensity for artificial indoor lighting. After the acclimatization period, Lc was lower than 9 µmol m-2 s-1 PPFD for all species and both CO2 concentrations while Rd was contained between -1.2 and -0.1, with significantly higher values at 800 ppm CO2 only in Aglaonema, Dieffenbachia and Spathiphyllum. At PPFD of 200 μmol m-2s-1, CO2 enrichment increased assimilation from 34.7 (Ph. erubescens) to 93.1% (Syngonium), reaching 1.42 in Ph. erubescens and 6.26 umol CO2 × m-2 s-1 in Ph. pertusum. The high AQE values in Ph. pertusum, Ph. erubescens, Syngonium and Dieffenbachia demonstrate the relatively higher capacity of the four Araceas to promptly react to increased light and sun flecks, when grown under a low photon flux density