Net Carbon Dioxide Exchange Rates and Predicted Growth Patterns in Alstroemeria `Jacqueline' at Varying Irradiances, Carbon Dioxide Concentrations, and Air Temperatures

The influence of irradiance, CO 2 concentration, and air temperature on leaf and whole-plant net C exchange rate (NCER) of Alstroemeria `Jacqueline' was studied. At ambient CO 2 , leaf net photosynthesis was maximum at irradiances above 600 μmol·m -2 ·s -1 photosynthetically active radiation (PAR), while whole-plant NCER required 1200 μmol·m -2 ·s -1 PAR to be saturated. Leaf and whole-plant NCERs were doubled under CO 2 enrichment of 1500 to 2000 μl CO 2 /liter. Leaf and whole-plant NCERs declined as temperature increased from 20 to 35C. Whereas the optimum temperature range for leaf net photosynthesis was 17 to 23C, whole-plant NCER, even at high light and high CO 2 , declined above 12C. Dark respiration of leaves and whole plants increased with a Q 10 of ≈2 at 15 to 35C. In an analysis of day effects, irradiance, CO 2 concentration, and temperature contributed 58%, 23%, and 14%, respectively, to the total variation in NCER explained by a second-order polynomial model ( R 2 = 0.85). Interactions among the factors accounted for 4% of the variation in day C assimilation. The potential whole-plant growth rates during varying greenhouse day and night temperature regimes were predicted for short- and long-day scenarios. The data are discussed with the view of designing experiments to test the importance of C gain in supporting flowering and high yield during routine harvest of Alstroemeria plants under commercial greenhouse conditions.