Abstract: The method of alkaline hydrolys acid fuchsin staining was used for determining the colonization of AM fungi in the root of Paeonia ostii. The content of soil hypha, spore density in soil and the activity of soil enzyme were also determined. The results showed that all roots samples were infected by AM fungi and formed the structure of Arum-type AM. AM fungal colonization rate in Triennial Paeonia ostii is smaller than the four-year-old Paeonia ostii′s which was smaller than the Biennial Paeonia ostii′s. Hypha colonization rate, content of paeonol and spore density in different years′ root samples showed the same trend as the AM fungal colonization rate. The colonization of vesicle in Triennial Paeonia ostii was smaller than that in Biennial Paeonia ostii′s, the biggest one was four-year-old Paeonia ostii′s. The colonization of hyphal coil showed the same trend as the colonization of vesicle.The activity of acid phosphatase, urease, sucrase and polyphenol oxidase was positively correlated with the content of soil hypha and negatively correlated with the colonization of Vesicle. The activity of acid phosphatase, sucrase and polyphenol oxidase was positively correlated with the colonization of hyphae circle and spore density, but negatively correlated with the urease activity. The activity of acid phosphatase was positively correlated with the colonization of hypha and AM fungi, but negatively correlated with the urease, sucrase and polyphenol oxidase′s activity. The research reveals the symbiotic relationship of AM fungi with the different year-old root of Paeonia ostii during period of dormancy and determinates the content of cortex moutan phenol and the activity of soil enzyme.

Key words: Paeonia ostii, arbuscular mycorrhizal fungi, colonization rate, soil enzyme activity, cortex moutan phenol, spore density, the content of soil hypha