EFFECTS OF SIMULATED ACID-RAIN ON THE PHOTOSYNTHETIC CHARACTERISTICS OF PHASEOLUS-VULGARIS L

A single treatment with a low pH solution of bean plants led to seriou s changes in the net photosynthetic rate (P-N) as well as in various p arameters of photosystem 2 (PS2) activity, A considerable suppression of P-N was established already in the first hours (3 and 5) following the acid treatment (pH 2.4-1.8). The period of strong inhibition of CO 2 uptake and photochemical activity was followed by the period of reco very (24-72 h), At a single spraying, pH values exceeding 2.0 did not lead to irreversible damages of the photosynthetic apparatus, The dama ges resulting from treatments with pH 2.0 and 1.8 were on the threshol d of irreversible ones and were the cause of faster ageing.