DETECTION AND IDENTIFICATION OF SEED BORNE PATHOGENS OF IMPORTED HYBRID RICE VARIETIES IN BANGLADESH

Abstract

The experiment was carried out at Sher-e-Bangla Agricultural University during 2008-09 according to the 1STA rules following blotter method, agar plate method and rolled paper towel method. Thirteen imported hybrids, two local hybrids and two local high yielding varieties were tested to determine the seed health status. A total of twelve pathogens were associated with the collected seeds viz. Xanthomonas spp, Rhizopus stolonifer, Aspergillus spp., Bipolaris oryzae, Fusarium moniliforme, Curvularia lunata, Penicillum sp., Tilletia barclayana, Alternaria tenuissima, Chaetomium globosum, Phoma sp and Nigrospora sp. The incidence of different pathogens vary individually and independently among the hybrids and local varieties of rice seeds. Seed germination varied from 54.63%- 99.50% in blotter method. The incidence range of Xanthomonas spp. (0 -18.13%), Rhizopus stolonifer (0-19.75%), Aspergillus spp. (0-12.00%), Bipolaris oryzae (0- 18.00%), Curvularia lunata (0-4.25%), Penicillum sp. (0-1.75%), Tilletia barciayana (0-2.75%), Alternaria tenuissima (0-0.63%), Chaetomium globosum (0-1.25%), Phoma sp (0-0.50%) and Nigrospora sp.(0-0.25%) were detected by blotter method. Seed germination ranged from 8.25%96.38% was recorded in rolled paper towel method. Non germinated hard seed ranged from 1.63%86.50% and rotten seed 0.75%-12.00%. Post emergence mortality was observed 0-4.38% by rolled paper towel method. The vigour index ranged from 96.36%-2329.28%. The incidence range of Xanthomonas spp. (1.63%-5.13%), Rhizopus stolonifer (0-3.00%), Bipolaris oryzae (0-15.13%), Fusarium moniliforme (0-7.63%), Curvularia lunata (0-6.38%), Penicillum sp.(0-1.63%), Alternaria tenuissima (0-1.63%), Aspergillus flavus (0·6.50), Aspergillus niger (0-1.38%) sp and Nigrospora sp.(0-1.38%) was detected by agar plate method. The detected predominant pathogens were Xanthomonas spp., Bipolaris oryzae, Aspergillus sp. Fusarium moniliforme ,Rhizopus stolonifer.