Arbuscular Mycorrhizal Fungi Alter Plant Growth, Soil Aggregate Stability, and Rhizospheric Organic Carbon Pools of Citrus

The effects of an arbuscular mycorrhizal fungus, Glomus mosseae, on plant growth, soil aggregate stability, and rhizosphere carbon pools of young Citrus junos seedings were investigated with potted experiment in greenhouse. After three months of mycorrhizal inoculation, root colonization was 54.25%. Inoculation with G. mosseae significantly promoted plant height, stem diameter, leaf number, and shoot and root fresh weights. Colonization by G. mosseae significantly increased soil aggregate stability of the citrus rhizosphere through increase of mean weight diameter. G. mosseae could release a specific glycoprotein viz. glomalin into the rhizosphere as glomalin-related soil protein (GRSP). Meanwhile, mycorrhizal colonization was significantly positively correlated with two GRSP fractions. In stabilization of aggregate stability, in GRSP fractions only easy extractable -GRSP might contribute the role. The mycorrhizal symbiosis could increase soil organic carbon, hot-water extractable carbohydrates, and hydrolyzed carbohydrates concentrations, but the differences were not significant. Combined with the correlation analysis, it suggests that GRPS did not significantly regulate rhizospheric carbon pools, due to the short treated time (only 3 months).