Environmental effects on net carbon exchange in Alstroemeri

The influence of irradiance, CO$sb2$ concentration, and temperature on leaf and whole plant net carbon exchange rate (NCER) of Alstroemeria cv. Jacqueline was studied.;Light saturation occurred between 400-600, and 1200-1500 $mu$mol m$sp{-2}$ s$sp{-1}$ for leaf and whole plant, respectively, with maximum NCER's ranging from 9-11 for leaf, and 5.0-5.5 $mu$mol CO$sb2$ m$sp{-2}$ s$sp{-1}$ for whole plant. Carbon dioxide saturation was estimated at 1300-1500 $mu$L L$sp{-1}$ for both leaf and whole plant, with maximum NCER'S ranging from 17-19 and 8.5-9.5 $mu$mol CO$sb2$ m$sp{-2}$ s$sp{-1}$ for leaf and whole plant, respectively. While optimum temperature range for leaf photosynthesis was 15-20$spcirc$C, temperatures below 15$spcirc$C were favourable for whole plant NCER. Whole plant NCER declined considerably at temperatures above 25$spcirc$C. Whole plant dark respiration increased significantly with temperature.;A second order polynomial predicted whole plant NCER at various serial environments. Irradiance, CO$sb2$ concentration, and temperature contributed 58%, 23%, and 14%, respectively, to the total variation in NCER. Interactions between the above factors were significant.