RHIZOSPHERE MYCOFLORA OF SOME SPECIES OF MYRISTICACEAE OF THE WESTERN GHATS, INDIAP. RAMA BHAT AND K.M. KAVERIAPPA
Rhizosphere mycoflora of Gy mnacranthera farquhariana, Knema attenuata, Myristica dactyloides, M. fatua var. magnifica and M. malabarica was studied by soil plating and soil dilution methods. The soil samples were collected from the rhizospheres of each tree species in three seasons namely, summer, monsoon and post-monsoon over a period of two years from the forests of Gersoppa, Uttara Kannada district of Karnataka. The physico-chemical parameters such as soil moisture, temperature, pH, EC, OM, elements like N, P. K, Ca, Cu, Fe, Mn, Mg, Na and Zn were analysed using standard procedures. A total of 99 species of fungi were isolated from the rhizosphere of five tree species and 49 species from the non-rhizosphere region. Only six out of 49 species isolated from non-rhizopshere soils were not observed in the rhizosphere soils. However, fifty out of 99 rhizosphere fungal species were not observed in the non-rhizopshere soils. The Sorensen's index showed the dissimilarity between the mvcoflora of rhizosphere and non-rhizosphere soil to the extent of 35-38%. Among the five tree species, a maximum of 73 fungal species were isolated from the rhizosphere of M. fatua var. magnifica followed by 67 species in G. farquhariana, 65 species in K. attenuate, 64 species M. malabarica and 63 species in M. dactuloities. Whereas 37 species were common to the rhizosphere of all the five tree species and 17 species were observed in the rhiosphere of only one of the five tree species. The dissimilarity was 12-28% within five tree species. Season-wise maximum number of fungal species were recorded during monsoon in all plant species and minimum during post-monsoon as well as summer. The physico-chemical parameter of the rhizosphere varied in different plant species in different seasons. The dominant genera in terms of number of fungal species were Pcnicillium and Aspergillus. Trichoderma viride was dominant species in most of the seasons. The rhizosphere effect in the five tree species was in the range of 6.13-25.9 with the maximum (25.9) in Knem attettuata in the post-monsoon season. The rhizosphere fungal population of different seasons in each plant species was correlated with physico-chemical parameters of respective seasons and found that it was significant in some of the seasons or for some parameters only.
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