2018 ASHS Annual Conference

Separate plastic tissue culture containers containing four ornamental plant species/hybrids (Anigozanthus flavidus, Aloe vera, Dionea muscipula, a Trichopilia hybrid, and a Phalaenopsis hybrid) that differed in perceived irradiance requirements were acquired from two commercial laboratories. Holes were drilled in the sides of the containers and a plastic tube and rubber stopper were inserted in each (a hole was drilled in the stopper to insert the plastic tube) to create an air-tight flow-through system compatible with a portable photosynthesis meter (LiCor LI-6400) to determine initial container carbon dioxide concentration (CO₂) under typical lab conditions (50 umol m^-2s^-1, 23 ^oC). Following this initial CO₂ measurement, photosynthetic CO₂-response curves were developed for the change in CO₂ entering versus exiting each chamber (approximates photosynthesis) as CO₂ levels increased from 25 up to 1300 ppm (species specific) while maintaining irradiance at 50 umol m^-2s^-1. Photosynthetic irradiance-response curves (0 up to 1300 umol m^-2s^-1; species specific) were then determined (based on changes in CO₂ concentration entering versus exiting containers) at the initial CO₂ levels measured for each flask (approx. 25 to 275 ppm for each species) to ascertain the impact of increasing irradiance under lab conditions. Lastly, both irradiance and CO₂ were simultaneously increased from lab conditions to the irradiance and CO₂ saturation levels determined above to establish the maximum potential increase in photosynthesis of each species. Implications of this work in tissue culture production when considering increasing irradiance and/or injecting CO₂ will be discussed.