Abstract: Bruguiera gymnorrhiza seedlings in sandy culture were treated with Hoagland nutrient solution containing 0〖KG-*2〗-〖KG-*7〗40 mmol·L-1 of Pb(NO3)2. After treated for two months, the activities of peroxidase (POD), superoxide dismutase (SOD), and catalase (CAT) were determined, and their isoenzymes were analyzed by electrophoresis. The results showed that the activities of antioxidant enzymes in B. gymnorrhiza seedlings roots and leaves increased under 1〖KG-*2〗-〖KG-*7〗10 mmol ·L-1 Pb but decreased under 20〖KG-*2〗-〖KG-*7〗40 mmol·L-1 Pb. Lead mainly affected the activities of anion type POD isoenzymes. 20〖KG-*2〗-〖KG-*7〗40 mmol·L-1 Pb strongly inhibited the activities of all CAT isoenzymes in roots, while 30〖KG-*2〗-〖KG-*7〗40 mmol·L-1Pb induced one additional Cu/Zn-SOD isoenzyme LS-3 and three additional CAT isoenzymes RC-3, LC-2, and LC-3.

Key words: Pig manure, Composting, Microbial agent, NH₃