Many studies have demonstrated that the application of organic amendments can improve the systematic resistance of plants [7,14]. Lipid peroxidation, which occurs in response to stress, results in the accumulation of MDA [21]. Therefore, increased level of MDA are indicative of the oxidative damage to cell membranes as a result of lipid peroxidation. In the present study, the application of seaweed fertilizer increased the activities of SOD, CAT, and POD, leading to reduced concentrations of MDA in the roots of M. hupehensis Rehd. seedlings