The present study is concerned with investigation of the mycorrhizal dependency on the lettuce plants not only to determine their growth but also for the multiplication of mycorrhiza inoculum. Mycorrhizal spores were collected from five weed plants in Mawlamyine University Campus by using floating adhesion technique (Sutton and Barron, 1972) and wet sieving method (Gerdmann and Nicolson, 1963). Mycorrhiza, collected from five selected weeds plants were mixed with sterile soil and inoculate on lettuce plants. Spores density and mycorrhizal colonization from rhizosphere of lettuce plants were recorded in every two weeks. Among five selected weed plants, the maximum rate of spore number and the highest colonization percent of mycorrhiza (77% in November) were found from source plant of Eclipta alba ( L.) Hassk. (Kyeik hman). Mycorrhiza isolated from Eclipta alba ( L.) Hassk. (Kyeik hman) were used as natural mycorrhizal inoculum (nmi) and subjected into seedling of Lactuca sativa L.(lettuce) by using polyethylene bag experiments with different treatment. Mycorrhizal dependency of lettuce plants were evaluated with mycorrhizal inoculum potential assay (MIP) method (Jarstfer, A.G. 2002). According to the result, the highest mycorrhiza inoculum potential (MIP) index were obtained in combination of 1 kg (nmi) + 3.5 kg (Soil) T2 (10.50) and 1 kg (nmi) + 0.5 kg (Cow Dung) + 3.5 kg (Soil) T4 (10.50) respectively.

Keywords : Weed, Mycorrhizal Dependency, Mycorrhizal Inoculum, Spores, Eclipta Alba (L.) Hassk., Lactuca Sativa L.