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

hotosynthetic 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. The 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 different measurement dates, the non-linear mixed-effects regression analysis was used. The model successfully described the photosynthetic responses. The analysis indicated significant differences in light saturated photosynthetic rates and in light compensation points. The cultivar with the lower light compensation points (Escimo) maintained a higher carbon gain despite its lower (but not-significant) quantum efficiency. The results suggested acclimation response, as carbon assimilation rates and stomatal conductance at each measurement date were higher for Escimo than Mercedes. Differences in photosynthesis rates were attributed to the adaptive capacity of the cultivars to light conditions at a specific day when the experiments were undertaken.