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Roots and rhizosphere soils of Acacia auriculiformis A. Cunn. ex Benth., A. mangium Wild., Artocarpus heterophyllus Lamk. C., Dalbergia sissoo Roxb. ex A. P. D., Eucalyptus camaldulensis Dehnn., Hevea brasiliensis (Wild. ex Juss) Muell. Arg., Swietenia macrophylla King. and Tectona grandis L. were collected from different locations of Madhupur forest area to study the biodiversity of Arbuscular Mycorrhizal (AM) fungal colonization and spore population. All the plants showed AM colonization. Out of eight selected plants, mycelial colonization was lowest in the roots of A. heterophyllus (22%) and the highest was in the roots of H. brasiliensis (78%). Mycelial intensity was observed poor (25%−77%) and moderate (23%−57%) in all plants species and abundant (11%−40%) was in most of the plant species. Vesicular colonization was observed in five plant species. The lowest was recorded in E. camaldulensis (4%) and the highest was in H. brasiliensis (21%). Poor (24%−56%), moderate (16%−100%) and abundant (11%−40%) type of vesicular intensity were observed. Arbuscular colonization was observed in three plants. The highest was in A. mangium (72%) and the lowest was in S. macrophylla (17%). Arbuscular intensity was recorded as poor (12%−44%), moderate (22%−100%) and abundant (4%−47%). The highest AM fungal spore population was in A. auriculiformis (714) and the lowest was in D. sissoo (102). Five AM fungal genera were recorded. Glomus was found to be dominant. A few spores remained unidentified. Significant correlation was observed between percent colonization and spore population. The results of the present study indicate the occurrence of AM fungi and the mycotrophism of the plants of Madhupur forest area and the applicability of AM technology in the forest management of Madhupur forest.

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Biodiversity of arbuscular mycorrhizal colonization and spore population was investigated in different agroforestry trees and crop species collected from different locations of Dinajpur district of Bangladesh. Roots and rhizosphere soils of Albizia procera Benth., Capsicum frutescens L, Curcuma domestica Vahl., Dalbergia sissoo Roxb. and Swietenia macrophylla King. from Dashmail; C. domestica, D. sissoo, Eucalyptus camaldulensis Dehnn., Gmelina arborea (Roxb) DC and Oryza sativa L. from Kantaji and C. domestica, D. sissoo, Litchi chinensis Sonn. and O. sativa from Ramsagar were collected. Roots and soils were assessed following standard methods. The range of AM colonization was recorded 36%−79% from Dashmail. The highest AM colonization was recorded in C. frutescens (79%) and the lowest was in C. domestica (36%). The range of colonization was recorded as 33%−70% from Kantaji. The highest AM colonization was recorded in G. arborea (70%) and the lowest was in O. sativa (33%). The range of AM colonization was recorded as 35%−70% from Ramsagar. The highest AM colonization was recorded in D. sissoo (70%) and the lowest was in O. sativa (35%). Arbuscular mycorrhizal spore population varied from 54 to 140/100g dry soil in the soils from Dashmail. The highest was in the soils of D. sissoo (140) and the lowest was in C. domestica (54). The spore population varied from 63 to 221 in Kantaji. The highest was in G. arborea (221) and the lowest was in O. sativa (63). The range population in Ramsagar varied from 69 to 160. The highest was recorded in D. sissoo (160) and the lowest was in L. chinensis (69). No significant relationship of soil pH and soil OM with AM colonization and with spore population was observed. Simpson's index of diversity (Ds) and Shannon's index of diversity-(Hs) were highest in the soil of D. sissoo from Kantaji and the lowest in the soils of O. sativa from Ramsagar. Biodiversity of AM colonization, spore population and the distribution of AM fungi in the rhizosphere soils of different agroforestry plants indicated the occurrence of AM fungi, mycotrophic nature of the trees and crop species, contribution and necessity of AM fungi and the AM dependence of the agroforestry plants growing in Dinajpur district of Bangladesh.

Microbial Inoculants as Effective Microorganisms (EM) were applied to find out their effects on germination and seedling growth of Albizia saman in the nursery. The seedlings were grown in a mixture of sandy soils and cow dung (3:1) kept in polybags. The EM solution at different concentrations (0.1%, 0.5%, 1%, 2%, 5% and 10%) was incorporated before and after a week of sowing seeds. Germination and physical growth parameters, including shoot and root length, vigor index, collar diameter, leaf number, fresh and dry weight of shoot and root and total biomass increment over the control were measured. The nodulation status influenced by EM was also observed along with the estimation of chemical parameters like chlorophyll a, chlorophyll b and carotenoid. Both germination and the measured physical growth parameters were found significantly (P<0.05) higher in seedlings treated with different concentrations of EM solution in comparison to the control. Maximum growth was found at 2% followed by 1% EM solution. Nodulation was higher at 0.1% concentration but it normally decreased with the increase of concentrations. Although there were a higher amount of pigments in leaves of the treated seedlings than of the control, the variations recorded with respect to chlorophyll a, b and carotenoid were not significantly higher in most of the treatments. Treated seedlings showed variable results along with the increment of EM applications and most of the parameters showed best results at the medium range of concentrations. The study indicates that the Microbial Inoculant (EM) technology might be useful to improve the growth of seedlings in the nursery. This also indicates that the associated beneficial organisms along with the polybag soils might be of value in improving the degraded soil or poor field soil for better nutrient and water uptake during the initial growth of transplanted seedlings.