Relationship between population density of root-knot nematode, Meloidogyne graminicola and the growth and nutrient uptake of rice plant

Abstract

Root-knot nematodes cause hypertrophy and hyperplasia of the vascular and cortical root tissues that reduce the absorption and transport of nutrients and water from soil. Aboveground symptoms are mistaken as nutrient deficiencies. The farmers tend to apply higher doses of fertilizers than necessary for a nematode-free crop, that not only causes economic loss but also avoidable soil and groundwater pollution. The nitrogen (N), phosphorus (P), potassium (K), iron (Fe) and zinc (Zn) contents were determined in the rhizosphere soil and leaves of a non-basmati Pusa-44 and a basmati Pusa Sugandh-5 cultivars of rice grown in soil infested with varying levels of Meloidogyne graminicola under pot and field conditions. The N, P, K, Fe and Zn contents in the rice leaves were significantly reduced in both the rice cultivars infestated with M. graminicola under both pot and field conditions. The degree of reduction did not significantly differ in the two cultivars. Pusa Sugandh-5 had relatively greater biomass than Pusa-44, but both the cultivars appeared to be similarly susceptible to M. graminicola. The residual contents of N, P, K, Fe and Zn in soil were more with increasing nematode population. Thus, the nutrients remained unutilized in the soil while the plant suffered severe nutrient deficiencies and growth reduction in the presence of nematode infestation.