[Effects of AM fungi on drought tolerance of citrus grafting seedling trifoliate orange/cara cara].

With pot experiment in a greenhouse, this paper studied the effects of arbuscular mycorrhizal (AM) fungi Glomus mosseae on the drought tolerance of citrus grafting seedling trifoliate orange/cara cara under natural water stress and rewatering. The results showed that inoculation with AM fungi significantly increased the plant height, stem diameter, leaf area, and shoot length of test seedling. At the 4th day of rewatering, mycorrhizal plant had significantly higher root soluble protein content and superoxide dismutase (SOD) and catalase (CAT) activities than non-mycorrhizal plant. An interaction between water and AM fungi could significantly promote leaf SOD activity. During natural water stress and rewatering, AM fungi inoculation could decrease the leaf content of malondialdehyde (MDA), increase those of soluble sugar and soluble protein, and enhance the activities of SOD, peroxidase (POD) and CAT. As a result, the capability of osmotic adjustment and protective recovery, and thus, the drought tolerance of mycorrhizal citrus grafting seedling were improved. The mechanism that AM fungi could enhance the drought tolerance of host plant might be related to the protective system of host plant.