Rhizospheric Niche of Carrizo Citrange Seedlings Colonized by Arbuscular Mycorrhizal(AM) Fungi

In a pot experiment,citrange [Poncirus trifoliate(L.) raf.× Citrus sinensis(L.) Osbeck.] seedlings were inoculated with arbuscular mycorrhizal fungi(AM fungi) of Glomus intraradices,Glomus mosseae,Glomus versiforme and their mixture to study the impact of AM fungi inoculation on rhizosphere microecological environment of the seedlings.An infection rate of mycorrhizal fungi of 40%~80% was obtained in the roots of citrange seedling inoculated with AM fungi.Compared with the control,AM inoculation remarkably increased the vegetative growth of the seedlings,including their height,shoot base diameter and aboveground/belowground biomass.AM fungi inoculation influenced the microbial populations on the roots,and the numbers of bacteria,actinomycetes,fungi,azotobacteria,ammonifiers and cellulose decomposers and microbial biomass in the root zone increased significantly(p0.05).AM fungi enhanced the activities of alkalinity phosphatase and urease in the soil rhizosphere,and their activities were positively correlated with the infection rate of AM fungi(p0.01).Enrichment of N and P which could be directly absorbed by the plants occurred in the AM-inoculated rhizosphere soil,and their contents were significantly positively correlated with the mycorrhizal infection rate.Path analysis showed that mycorrhizal infection rate was co-influenced by soil microbes,enzyme activity,pH and nutrient contents in the rhizosphere through their direct or indirect actions.