Studies on seed borne nature of Fusarium oxysporum f. sp. carthami causing wilt of safflower.

摘要

Experiments were conducted to study the seedborne nature of Fusarium oxysporum f.sp. carthami on safflower seeds using the blotter paper method. Seeds of 5 safflower cultivars, i.e. Bhima, PBNS 12, Manjira, HUS-305 and PBNS-40, were placed on water soaked blotter paper and incubated at 20+or-2 degrees C in petri dishes for 7 days in alternating cycles of 12 h light and darkness. The individual seeds were examined and fungi were identified. The effect of seed treatment with fungicides, HgCl₂ and hot water on seed borne mycoflora of safflower was studied. Seeds of safflower cv. Nira were treated with carbendazim (0.3%), thiram (0.3%), carbendazim (0.15%) + thiram (0.15%) and captan (0.3%), surface sterilized with 0.1% HgCl₂ and treated with hot water at 52 degrees C. Untreated seeds were used as controls. After treatment, the seeds were placed on petri plates containing Fusarium-selective medium. Results showed that the highest incidence of F. oxysporum f.sp. carthami was observed in Manjira, which was at par with PBNS-12, while the lowest incidence was observed in HUS-305, but at par with PBNS-40. The lowest incidence of Rhizopus spp. was also observed in Manjira, followed by PBNS-12, while HUS-305 had the highest incidence. Aspergillus spp. was high in HUS-305, followed by PBNS-40 and Bhima. In the agar plate method, the incidence of F. oxysporum f.sp. carthami was highest in unsterlized seeds, followed by seeds sterilized with mercuric chloride and captan. Lowest F. oxysporum f.sp. carthami was observed in seeds treated with hot water. Lowest incidence of Rhizopus spp was observed in seeds treated with carbendazim followed by unsterilized seeds, while maximum incidence was observed in seeds sterilized with mercuric chloride. The lowest Rhizopus spp. incidence was observed in seeds treated with carbendazim, followed by unsterilized seeds, while maximum incidence was observed in seeds sterilized with mercuric chloride. The lowest Aspergillus spp. incidence was observed in seeds treated with carbendazim + thiram, followed by seeds treated in hot water and captan.