AIRSPORA MEASURED IN A PADDY FIELD IN WEST-BENGAL, INDIA

Aeromycoflora studies above an ''Aman'' variety of paddy (Oryza sativa L.) were carried out for two consecutive seasons, in 1990 and 1991, i n the vicinity of Barrackpore, West Bengal, by means of the culture pl ate exposure technique. A more or less uniform spore concentration was observed during the early part of the vegetative stages in 1990 with an abrupt increase and peak during the maximum vegetative growth perio d. In 1991, a uniform spore count was found up until the flowering sta ges. A gradual increase in spore count after flowering was recorded in both seasons with the highest peaks during harvesting, followed by a sudden decrease after the harvest. The dominant genera isolated were A spergillus, Curvularia, Cladosporium and Penicillium. Aspergillus appe ared in high concentrations from the very beginning of the crop season up to the flowering stages, with a gradual fall after flowering while Cladosporium showed the reverse pattern. Curvularia and Penicillium o ccurred regularly throughout the crop season. Phytopathogenic types we re represented by Helminthosporium oryzae, Fusarium, Alternaria and Ni grospora. Helminthosporium oryzae appeared in the air when the plants attained appreciable vegetative growth, bring seen as ''brown spots'' on the foliage, and reaching peak concentration during harvesting. Fus arium in contrast to Alternaria appeared regularly in the air except d uring the later part of vegetative growth. Nigrospora was recorded onl y occasionally. A considerable number of ''Sterile Forms'' were presen t throughout both seasons.