Effects of N, P and K fertilizer on antioxidant activities of mulberry leaves

The effects of different amount and ratio of nitrogen(N)、phosphate(P) and potassium(K) on the protective enzyme activity and membrane lipid peroxidation (MDA) of mulberry leaves were investigated in later stage in field test.The results indicted the contents of soluble protein(Pro),malondialdehyde(MDA) and the activities of superoxide dismutase(SOD),catalase(CAT),peroxidase(POD) gradually increased with mulberry development in spring.The Pro contents and the activities of SOD,CAT,POD increased firstly and decreased afterward and MDA gradually increased in autumn.With the increase of single fertilizer amount,the Pro contents and the activities of SOD,CAT,POD significantly increased and MDA significantly decrease and the optimal level was N2P2K2 at developmental period.Suitable fertilizer amount and ratio (N2P2K2:N 600 kg·ha-1 ,P2O5 210 kg·ha-1 ,K2O 300 kg·ha-1) significantly increased the protective enzymes activities and decreased lipid peroxidation degree of mulberry leaves which delay its aging.