Abstract: After exposed to elevated CO₂ ［T₁: (600±40) μmol·mol^-1 and T₂: (900±40) μmol·mol^-1］ for 150 days, Guzmania‘Luna’ and Guzmania‘Denise’ were transferred to ambient CO₂ for 30 days to investigate the recovery of their photosynthesis and their key photosynthetic enzyme activities. The results showed that compared with that in CK, the net photosynthetic rate (P_n) of Guzmania‘Luna’ in treatments T₁ and T₂ was decreased by 7.41% and 13.33%, respectively. The P_n of Guzmania‘Denise’ in T₁ was approached to CK, and that in T₂ was higher than CK. After 30 days recovery, the accumulation of soluble sugar and starch in test bromeliads leaves decreased obviously, with the contents being close to those of CK. The rubisco and glycolate oxidase activities in treatments T₁ and T₂ had a decreased difference with CK, but were still lower than those of CK.

Key words: Crop water shortage index, Drought, Remote sensing, Monitoring