Interaction between Arbuscular Mycorrhizal Fungi and Pythium aphanidermatum in Tobacco Seedbeds

The interaction studies between five VAM fungi, i.e., Glomus mosseae, G. fasciculatum, G. constrictum, G. intraradices, Glomus spp. (local isolate), Acaulospora laevis and damping-off ischolar_main rot pathogen (Pythium aphanidermatum) along with fungicide (mancozeb + metalaxyl) check on tobacco (Nicotiana tabacum L.) seedbeds revealed that all the VAM fungi colonized the ischolar_mains efficiently within 30 days of inoculation. However, the per cent colonization was higher in the seedlings inoculated with local isolate Glomus spp. The per cent disease severity in 24 day old seedlings was significantly less in treatments with VAM fungi compared to non-mycorrhizal treatment. The disease severity in mycorrhizal seedlings ranged from 31.33 to 63.33, and it was 26.6 per cent in fungicide treatment and 100 per cent in non-mycorrhizal pathogen inoculated control seedlings. The minimum disease severity was observed in the fungicide treatment and in the seedlings inoculated with Glomus spp. The increase in plant growth characteristics such as seedling height, leaf area, fresh and dry weights of the seedling was significantly higher in pathogen inoculated mycorrhizal seedlings as compared to non-mycorrhizal pathogen inoculated seedlings. Total leaf cholorophyll content and nutrients N, P, K, Zn, Cu, Fe and Mn were higher in mycorrhizal seedlings compared to the non-mycorrhizal seedlings.