INFLUENCE OF PHOTOINHIBITION ON PHOTOSYNTHESIS AND LIPID-PEROXIDATION

The effect of photoinhibition at 10 and 30-degrees-C on photosynthetic electron transport, chlorophyll fluorescence and peroxidation of thylakoid lipids was studied in intact leaves, isolated chloroplasts and photosystem (PS) II and I particles. Photoinhibition impaired the photochemistry of PS II, whose activity was more significantly affected than that of PS I. The extent of the damage was greater at 30-degrees-C than at 10-degrees-C. Peroxidation of thylakoid lipids, measured in isolated chloroplasts and PS II particles, was also greater at 30-degrees-C, but peroxidation of PS I particles was almost the same at the two temperatures. The recovery of thylakoid lipids and the F(v)/F(m) ratio after 6 h of photoinhibition was complete within 12 h in intact leaves under the growth conditions.