The data for photosynthesis and chlorophyll fluorescence were similar for tomato plants grown in a growth chamber at a similar age (Nogués et al., 2002). Measures of photosynthesis showed that plants grown in CM behave as plants grown at high light intensity (measure carried out at 1200lmolm2s1 PPFD). This value contrasts with that found for plants grown in all other treatments, which were saturated at this light level. Measures of chlorophyll fluorescence were similar among treatments and the Fv/Fm ratios in all treatments were over 0.75, which is considered the limit for photoinhibition (Björkman and Demmig, 1987).