Airspora Studies Over a Rice (High Yielding Variety) Field in Rabi Season in the State of West Bengal, India

Aeromycoflora studies over a paddy field in West Bengal during rabi season were initiated with the help of culture plate exposure technique for two consecutive crop seasons. The total CFUs was found to vary with growth stages, since the null hypothesis about the number of spores at different stages got rejected at 5% level of significance. A more or less uniform spore count was recorded up to maximum vegetative growth stages after that there were a gradual rise in count with peaks (214 and 444CFUs, respectively) during harvesting of the two crop seasons. A number of fungi was isolated.. The dominant genus identified was Cladosporium which appeared in huge amount in the earlier stages; declined gradually in late stages with the onset of summer showing a seasonal periodicity. Penicillium showed a reverse picture. Its' predominancy was increased with the termination of winter and simultaneously increased with increase in temperature. Curvularia showed no seasonal variation. Alternaria, Fusarium, Helminthosporium and Nigrospora were the phytopathogenic fungi recorded from air; of which Alternaria was the dominant. Alternaria was recorded to be present regularly with peaks at flowering onwards. A species of Alternaria was detected as a virulent disease causing agent in this variety of rice which caused leaf damage to the host plant. It was heavily present at later stages, also confirmed by statistical analysis. Fusarium, Helminthosporium and Nigrospora were found more or less frequently. Fungi failed to sporulate were grouped under sterile forms and were found regularly throughout the period of investigation.