Non-linear mixed-effects modeling for photosynhetic response of Rosa hybrida L. under elevated CO₂ in greenhouses - short communication

Photosynthetic response to light was measured on the leaves of two cultivars of Rosa hybrida L. (Escimo and Mercedes)
in the greenhouse to obtain light-response curves and their parameters. Th e aim was to use a model to simulate leaf
photosynthetic carbon gain with respect to environmental conditions. Leaf gas exchanges were measured at 11 light
intensities from 0 to 1,400 µmol/m2s, at 800 ppm CO2, 25°C, and 65 ± 5% relative humidity. In order to describe the data
corresponding to diff erent measurement dates, the non-linear mixed-eff ects regression analysis was used. Th e model
successfully described the photosynthetic responses. Th e analysis indicated signifi cant diff erences in light saturated
photosynthetic rates and in light compensation points. Th e cultivar with the lower light compensation points (Escimo)
maintained a higher carbon gain despite its lower (but not-signifi cant) quantum effi ciency. Th e results suggested acclimation
response, as carbon assimilation rates and stomatal conductance at each measurement date were higher for
Escimo than Mercedes. Diff erences in photosynthesis rates were attributed to the adaptive capacity of the cultivars to
light conditions at a specifi c day when the experiments were undertaken.