Effect of Physico-Chemical Properties of Soil on Rice Root-Knot Nematode (Meloidogyne graminicola) in Major Rice Growing Districts of Karnataka, India

The present study was conducted to find out the relationship of physico-chemical properties viz.,pH, electrical conductivity (EC), organic carbon (OC), soil moisture, nitrogen, phosphorus, potassium and micro nutrients content of rice growing soil with incidence of rice root-knot nematode (Meloidogyne graminicola) of rice. To investigate the effect of physicochemical properties of soil on incidence of Rice root-knot nematode (Meloidogyne graminicola)in major rice growing districts of Karnataka stateviz.,Shivamogga, Chikmagaluru, Davanagere, Mandya, Kodagu, Udupi and Karnataka. Systematic surveys were during Kharif2015 and 2016 in major rice growing districts and estimated nematode population and analyzed physicochemical properties of soil under laboratory. The results revealed thatin Chi-kadadkatte village of Davanagere district, V.C Farm of Mandya district, Tuduru, Beguvalli, Hasudi village of Shivamogga, Karagunda, Lakkavalli of Chickmagaluru and Mikere village of Kodagu district recorded highest incidence with nematode population ranging between 586.33 to 841.00 J2/200 cc of soil and Root Knot Indices(RKI) varying from 3 to 4. These locations had sandy loamy soil, with acidic soil pH, lower soil organic carbon, phosphorous and potassium and higher nitrogen and moisture content. Analyses of correlation of coefficient showed that population of M. graminicola had significantly positive correlation with soil moisture, nitrogen, soil organic carbon at (P<0.01) while significantly negative correlation with other physico chemical properties of soil viz., soil pH, soil EC, phosphorus, potassium, sulpher, zinc and manganese. The results of the present study show that the sandy loamy soil, with acidic soil pH, lower soil organic carbon, higher nitrogen, lower phosphorous and potassium and higher moisture play a major role in survival of M. graminicola and influence in incidence of rootknot disease incidence in rice.