Molecular characterization and influence of soil factors on isolates of Rhizoctonia solani in Meghalaya
2016
B.U. CHOUDHURY, D. MAJUMDER, T. RAJESH | D.M. FIRAKE, K. MAHENDRA, P. BAISWAR*, S. CHANDRA,
Disease samples of sheath blight of rice, and banded leaf and sheath blight of maize were collected randomly from four districts of Meghalaya. Molecular characterization using specific primers and universal fungal primers revealed that most of the isolates belonged to anastomosis group AG1-IA. Differential growth rate was observed in 15 rice isolates of R. solani with maximum growth rate observed in two rice isolates, KMR6 and KMR8 that covered whole petri plates within 2 days of inoculation. Out of 12 maize isolates, KMM7 covered whole plate in 36 hours of inoculation. Virulence analysis of 15 rice isolates by detached tiller method revealed that isolates KMR2, KMR3, KMR4, KMR5, KMR6, KMR7, KMR8, KMR11, KMR12, KMR13 and KMR15 were virulent and other isolates were non-virulent. While detached leaf assay of maize showed that the isolates KMM4, KMM6, KMM7 and KMM8 were virulent and other isolates were non-virulent. Thirty six soil samples were collected from across the Meghalaya state and analyzed for soil pH, soil organic carbon (SOC), soil texture and available nutrients (N, P and K). Correlation analysis revealed that growth of KMM7 isolate in soil was significantly correlated with sand%, SOC, pH and available phosphorus (kg/ha) in soil. By using Step wise regression analysis, soil pH was detected as the most important variable. Among all equations evaluated (quadratic, inverse, logarithmic and linear), quadratic (adjusted R2 - 0.52) and linear (adjusted R2 - 0.45) were found to explain the variability better than other equations.
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