The rhizospheric soil and roots were collected from five different sites of Northeast India, where Oroxylum indicum was naturally growing in its ecological habitat and were analysed. The study revealed that the roots of
O. indicum were colonized with AM spores and the soil nutrient content plays a major role in the colonization of the AM spores. A total of 23 species of AM fungi belonging to four genera viz., Glomus, Acaulospora, Gigaspora,
Entrophospora and Pacispora were recovered from the rhizosphere of O. indicum. The statistical analysis of the data revealed that the AM spore count is positively correlated with the soil nutrient status. AM spore count was maximum in forest fringe and agricultural farmland, hyphal and arbuscular colonization percentage was higher in agricultural farmland, while the vescicular colonization percentage was maximum in the rhizospheric soil of agricultural farmland and forest fringe areas. The AM spore count of O. indicum growing near the roadside showed positive correlation with root colonization. The correlation value of (0.766, 0.413, and 0.567) was obtained when root colonization was compared with soil organic carbon percentage, soil nitrogen and potassium content.
