Detection and management of seed-borne microflora associated with rice seeds in Himachal Pradesh

Twelve seed samples of different rice varieties from two agroclimatic zones of Himachal Pradesh tested for associated microflora, showed the presence of 15 fungi by blotter method and 17 fungi and 1 bacterium sp. by agar-plate method. Among various methods, agar plate method was more efficient in detection of microflora. Curvularia lunata, Drechslera oryzae and Xanthomonas sp. were the predominant pathogens with highest frequency whereas Fusarium solani was detected from all the varieties with 100 per cent sample mean. Among the varieties, maximum microflora was detected from variety Kasturi Basmati and minimum from variety Pusa-1121, Jhumka and HKR-126. Only one nematode species, Aphelenchoides besseyi was detected from varieties Pusa-1121 and Jattoo. Seed treatment with chemicals (Bavistin + Dithane M-45 @ 1.25 + 1.25 g/kg seed) had significant effect against different seedborne fungi. In all 12 species were recorded on the chemical treated seeds though the number of fungi on individual seed lots ranged from 0 to 7 species with complete control of microflora from variety HKR-126. Seed treatment with bioagents Trichoderma harzianum talc based formulation @ 4 g/kg seed restricted the growth of pathogens in all varieties and gave complete control of a number of fungi and bacteria associated with rice seeds through agar plate method.