Effect of cadmium on multiplication of the root-knot nematode, Meloidogyne incognita and its accumulation in tomato plants

Abstract

Heavy metal pollution is posing a problem as it is continuously being added to agricultural soils through industrial effluents in wastewater. In the present study, tomato (Solanum lycopersicum cv. Pusa Ruby) plants were treated with the soil pollutant cadmium in the presence of the root-knot nematode, Meloidogyne incognita. The soil was treated with 7.5, 15.0, 30.0 and 60.0 ppm concentration of Cd and subsequently inoculated with 5,000 second stage juveniles of M. incognita/pot. There was an antagonistic association between Cd and the nematode. Nematode disease severity (i.e. degree of galling) decreased with the increase in concentration of the heavy metal. A decrease was also observed in nematode reproduction (eggs/egg mass and egg masses/root system) and size of soil population at all concentrations of Cd. Accumulation of the heavy metal was greater in nematode infected plants than in uninfected plants and in roots as compared to shoots in both the infected and uninfected tomato plants. Cadmium not only caused retardation in the growth of females but also caused aberration in their shapes. The degree of retardation and aberration was directly proportional to the concentration of the heavy metal. The antagonistic interaction between Cd and M. incognita multiplication was also found to be concentration dependent.