Impact of simulated acid rain on peroxidation of membrans lipids in leaves of papaya seedlings

Impact of simulated acid rain with various pH values(4. 5,3. 5,3. 0,2. 5)on leaf in different stages of papaya(Carica papaya L, )seedlings were studied. The results showed that permeability,MDA content,LOX activity,leakage amount of K+ ,Ca2+ and Mg2+ ,and saturated fatty acid increased with the decline of the pH value of simulated acid rain, unsaturated fatty acid and IUFA decreased with the decline of the pH value of simulated acid rain. The sensibility to acid rain of spire was higher than climax leaf. The injury threshold value of teneral leaf to simulated acid rain was pH≤3. 0 by the standard of the result using significance tested with L. S. D. at 0. 05 level,and that of adult leaf was pH≤3. 5.