Table 1 Soil chemical property of each sampling site at sampling time.

1. AMF colonization rate (%) Fig.1 Effects of superphosphate on AMF colonization rate of soybean roots. a a a a b BAE b HRT a PSR ab b Fig. 3 MDS (Multi-dimensional scaling) analysis of AMF community colonizing in soybean roots of P0 and P2 Plots . Fig. 2 Dendrogram of AMF colonized in soybean root. Effects of Phosphorus Fertilizer Application on the Community Structure of AMF Infected in Soybean Roots Katsunori Isobe*, Kohei Maruyama, Nao Yoshikawa and Ryuichi Ishii College of Bioresource Sciences, Nihon University, 1866 Kameino Fujisawa-City, Kanagawa 252-8510, Japan Table 1 Soil chemical property of each sampling site at sampling time. Table 2 Effects of superphosphate on the growth of soybean. Table 3 AMF phylotype colonized in P0 and P2 plots of soybean root. Phosphate (P) is one of most important nutrient for crop growth. Therefore, the application of the P fertilizers is necessary to the crop production. And, it is simultaneously bring to change of soil environment condition and soil microorganism ecology. In generally, hyphal growth and colonization of arbuscular myccorhizal (AM) fungi were decreased by the application of P phosphate. But, it is not cleared that P phosphate application or the increase of soil P content was affected to the AM fungal community structure or not (Alkan et al. 2006, Santos et al.2006.). Then, we investigate the effects of P fertilizer (superphosphate) level on community structure of AM fungi in the soybean (Glycine max (L.) Merr.). In three fields (two fields (PSR and BAE field) were in Nihon University (Fujisawa city, Japan), and one (HRT field) was the farmers field of Hiratsuka city, Japan) applicated at three superphosphate levels (P0-plot (0g P2O5 m-2), P1-plot (10g P2O5 m-2) and P2-plot (20g P2O5 m-2). Soybean roots were sampled in August 2007. The soybean growth stage of this time was flowering stage(R2). We examined the AM fungal colonization rate by a grid crossing-point method , growth of soybean and the composition of AM fungi phylotype in soybean roots by the method of Gollotte et al. (2004). And we analyzed the resemblance of colonized AM fungi phylotype in P0 plot and P2 plot by MDS (Multi dimensional scaling) analyze. The available phosphate content in field soils was generally increased and AM fungal colonization rate decreased with increasing application of superphosphate level (Table 1, 2, Fig.1). Available phosphate content of the PSR field was higher than that of other two fields. In this field, decreasing rate of AM fungal colonization by the application of superphosphate was smaller than other two fields (Fig.1). The composition of AM fungi phylotype colonized in soybean roots slightly changed, when superphosphate was applicated in the fields (Fig.2, Table 3). For example, the number of colonized AM fungi phylotype was from 8 to 17 in P0 plot, and in P2 plot, the number of that were from 7 to 16 (Table 3). Moreover, by the MDS analysis, the resemblance of colonized AM fungi phylotype did not change constantly, even if superphosphate was applicated in the fields (Fig.3). From the results above, we suggest that application of superphosphate causes the decreasing of colonization rate of AM fungi, but, dose not affect the colonized AM fungal community in soybean roots. Key words: Arbuscular mycorrhizal fungi, Community structure, Soybean (Glycine max (L.) Merr.), Superphosphate. Materials and Methods Results and Discussion References Alkan, N. et al. 2006. Appl.Environ.Microbiol. 72:4192-4199. Gollotte, A. et al. 2004. Mycorrhiza 14:111-117. Santos, J.C. et al. 2006. New Phytol. 172:159-168. ＊E-mail address isobe64@brs.nihon-u.ac.jp