Relationship between SOD Activity and Chlorophyll Content and Abnormal Defoliation of Soybean (Glycine max)Leaves Exposed to Airborne Fluoride

The relationship between superoxide dismutase(SOD)activity in soybean( Glycine max )planted in pot and some physiological indexes suchas chlorophyll(Chl)content,production of ethylene(C 2H 4)and activity of cellulase were studied by using the method of artificial fumigation with hydrogen fluoride(HF).Results showed that:(1)HF decreased the content of Chl in leaves by inhibiting activity of SOD;(2)HF raised the activity of celluase,an enzyme leading to abnormal defoliation,by inhibiting SOD activity and increasing C 2H 4 production. Therefore,the stability of SOD plays an important role in enhancing fluoride tolerance of plants.