EFFECTS OF LIGHT-INTENSITY ON PHOTOSYNTHESIS AND TOXIC O-2 SCAVENGINGENZYMES DURING ACCLIMATIZATION OF MICROPROPAGATED CALATHEA

Directly after transplantation, micropropagated Calathea louisae GAGNE P. 'Maui Queen' plantlets did not show any positive net photosynthetic activity (= heterotrophic metabolism), and photoinhibition exacerbate d with increasing light intensity as was shown by the decrease in F-v/ F-m. Recovery from light stress was observed during the second week af ter transfer, when plants became fully autotrophic. An inverse relatio n between light intensity and the total chlorophyll over carotenoid ra tio was found. Also changes in activities of antioxidative enzymes wer e observed. Catalase and glutathione reductase increased during the fi rst three weeks of acclimatization, while an increase in guaiacol pero xidase and ascorbate peroxidase was observed later on in the acclimati zation. Both superoxide dismutase and guaiacol peroxidase activities i ncreased with increasing light intensity, while catalase activity was reduced. The results suggest an adaptive response of the plants to str ess conditions generated by changes in climatic conditions at transpla ntation.