Effects of Rare Earth Lanthanum and Cerium on Antioxidant Enzyme Activities in Soybean Leaves

Rare earth has a long history of agricultural use and can improve the yield and quality of agricultural by-products,but its regulation mechanism is still unclear.The aim of the study was to investigate the effects of lanthanum and cerium on the activities of peroxidase,catalase and ascorbate peroxidase in leaves of soybeans [Glycine max （L.） Merr].Soybean varieties of Dongnong 42,Dongnong 47 and Dongnong 52 from Northeast China were used as experimental materials.The samples were tested by spraying different concentrations of LaCl3 (120,150 and 180 mg·L-1),CeCl3 (30,60 and 90 mg·L-1) and LaCl3+CeCl3 (30,40 and60 mg·L-1 mix) solutions on the leaves at the seedling stage and the early flowering stage of soybeans.The results showed that the suitable species and concentrations of lanthanum and cerium could increased the activities of antioxidant enzymes in soybean leaves,but the effects of lanthanum and cerium on different varieties of soybeans were also different.For Dongnong 42,the optimum lanthanum and cerium treatment was 60 mg·L-1 LaCl3+CeCl3,and the activities of peroxidase,catalase and ascorbate peroxidase increased by 11.36% （p<0.05）,13.89% （p>0.05） and 50.00% （p<0.05） compared with those of CK.The optimal lanthanum and cerium treatment of Dongnong 47 was40 mg·L-1 LaCl3+CeCl3.Compared with those of CK,the above three enzyme activities increased by 15.80% （p<0.05）,51.52% （p<0.05） and 20.75% （p>0.05）.The optimal lanthanum and cerium treatment of Dongnong 52 was 60 mg·L-1 LaCl3+CeCl3,which increased the activities of the three enzymes by 33.49% （p<0.05）,19.23% （p>0.05） and 23.53% （p<0.05） compared with those of CK.