isolation of mycorrhizal fungi
fungal isolates CMU-Aug 007,CMU-Aug 013,CMU-Aug 028,CMU-Aug 211 and CMU -AU 212 were isolated as described previously (Chutima et al.2011). The remaining fungai were isolated using amodified procedure of Zhu et al.(2008). Thirty roots (five cm segments) of each orchid species were first peeled by removing root hairs, epidermis and velamen with instruments,and then the segments were immersed in sterile water supplemented with 150µg/ml of streptomycin for 10 min and washed l time with sterile water.