The response of soybean plants grown in newly reclaimed soil to different fungal species of arbuscular mycorrhizal and phosphorus fertilization

A pot experiment was conducted to study the response of soybean plants (Glycine max), grown in soil collected from the newly reclaimed area, to root colonization with the different species of arbuscular mycorrhizal (Glomus moseae, Glomus monosporum, and Gigaspora margarita) and soil phosphorus fertilization. Fungal phosphatases and succinate dehydrogenase (vital stain) activities as enzyme markers were also investigated to detect the physiological activity of the mycorrhizal fungi. Two concentrations of KH2PO4 (0 and 0.5 g kg-1 soil) were used. External addition of soluble phosphorus increased all growth parameters, nutrient contents and biochemical parameters of both the mycorrhizal and nonmycorrhizal plants. The mycorrhizal colonization significantly increased some of the growth parameters, P and N concentrations in root and shoot tissues, root nodulation, acid and alkaline phosphatase activities and total soluble proteins in root extracts when compared to nonmycorrhizal plants. Such stimulations in these parameters were highly related to the level of each species of mycorrhizal colonization in the root tissues of soybean plants, particularly in soil without phosphorus. The addition of phosphorus to soil reduced the level of mycorrhizal colonization in the soybean root tissues, and consequently the mycorrhizal benefits. The efficiency of mycorrhizal fungi in this study for stimulating plant growth and nutrient contents was positively related to the activity of fungal succinate dehydrogenase stained in the root tissues.