No abstract

We investigated the mycorrhizal associations in 31 adult wild or cultivated green orchids (22 epiphytic, 8 terrestrial, and 1 species with both epiphytic and lithophytic life-forms) from different vegetation types of Western Ghats, southern India. All the orchids examined were mycorrhizal with the extent of colonization varying with species and life-forms. Mycorrhizal association has been reported for the first time in 25 orchids. The entry of mycorrhizal fungi into the roots was mostly through root hairs. In certain epiphytic species, the fungal entry was directly through the epidermis. The fungi formed highly coiled hyphal structures (pelotons) within the root cortex, and their size was related to the cell size. The fungal invasion of the cortical cells was through cell-tocell penetration. The cortical cells contained intact and lysed pelotons, and their ratio varied with species and lifeforms. No significant relationship existed between root hair characteristics and the extent of colonization. Chlamydospores and microsclerotia-like structure were frequently found within the cortical and root hair cells. The liberation of fungal reproductive structures was by spiral dehiscence of the root hairs.

-We examined roots of the shallot (Allium cepa L. var. aggregatum), one of the most popular cultivated crops of the family Aliaceae, cultivated under conventional agriculture for arbuscular mycorrhizal fungal (AMF) and dark septate fungal endophyte (DSE) associations. All the plants had dual colonization of both AMF and DSE associations. The intermediate-type AMF morphology in the shallot is the first report of this AMF type for the family Aliaceae. The extents of total AMF and DSE colonization ranged from 20.7 to 67.3% and 3.6 to 35.3% respectively and varied significantly among fields. Though no significant relationship existed between total AMF and DSE variables, they were correlated to the soil variables. Significant correlations existed between soil P and microscelerotia and also between soils N and K and AMF spore numbers. A total of six AMF spore morphotype belonging to Glomus and Scutellospora were identified. Scutellospora calospora was the most dominant morphotype in the studied fields.

No abstract

No abstract