Influence of Glomus Species and Soil Phosphorous on Verticillium Wilt in Bt Cotton

Amendment of single superphosphate to the soil was done at 20mg /kg and 300mg /kg. After that soil was treated with different treatments like a) Verticillium dahliae, b) Glomus species, c) both Verticillium and Glomus species d) None of Glomus species and Verticillium. The Verticillium wilt was more severe in plants infected with Glomus species than non-mycorrhizal plants fertigated at 20mg P / kg of soil. However, in plants fertigated with 300mg P / kg of soil, Verticillium wilt was equally severe in mycorrhizal and non-mycorrhizal plants. More propagules of V. dahliae were found in the plants fertigated with 20mg P / kg of soil, in petioles of mycorrhizal plants than that of non-mycorrhizal plants. The plants fertigated with 300mg P / kg of soil reported maximum number of propagules of V. dahliae were not significantly different in mycorrhizal and non-mycorrhizal plants. It was found that infection of V. dahliae in Bt cotton by Glomus species was not affected in plants fertigated with 20mg P / kg of soil. The infection was inhibited by phosphorous and further by V. dahliae in plants fertigated with 300mg P / kg of soil. The concentrations of phosphorous in the leaves of the treated plants were found similar to the treated mycorrhizal and non-mycorrhizal plants fertigated with 20mg P / kg of soil. The plants infected with V. dahliae alone were found lower than the plants infected with both V. dahliae and Glomus species.