S. RAJASEKARAN AND S.M. NAGARAJAN
Abstract
In total thirty common herbaceous plants of indigenous medicinal value, belonging to fourteen families of angiosperms growing in four different essentially agricultural areas of Thanjavur District in Tamil Nadu, India were screened for VAM colonization and their rhizospheric soils were analysed for different VAM spore structures. Of these 30 plants screened, only 26 were positive for VAM colonization. A very high degree of root colonization showing more than 75% was observed in 10 plant species. There was a fair correlation between the % of infection and the number of spores in root zone soil in many cases. Total 20 VAM fungal species belonging to seven different genera, viz. Glc»nus, Acaulospora, Sclerocystis, Scutellospora, Gigaspora, Entrophosphora and Endogone were recorded. Soil physicochemical characteristics played an important role in distribution and density of mycorrhizal fungi. A fairly detailed study employing different methods in histochemistry revealed the universal presence of chitoson, lipids and several insoluble polysaccharides in VAM structures.