The interactive relationship between the root–knot nematode Meloidogyne incognita and the root-rot fungus Macrophomina phaseolina in a root–rot disease complex of chickpea (Cicer arietinum var. avrodhi) was studied in a net house. The present study was carried out in such a manner so that the pathogenic potential of M. incognita and M. phaseolina individually, simultaneously and sequentially could be monitored. The pathogens singly as well as in combination led to significant reduction in growth, yield, nutrient and biochemical parameters. Gaseous exchange parameters like photosynthetic rate, transpiration rate and stomatal conductance were also reduced following infection of plants by the pathogens. However, maximum reduction was noticed in simultaneous inoculation with both pathogens. Sequential inoculation, where M. incognita preceded M. phaseolina by 15 days, was more damaging to the crop in comparison to that where M. phaseolina preceded M. incognita inoculation by 15 days. Infection by M. phaseolina caused a considerable reduction in the number of galls, egg–masses and nematode multiplication, with the highest reduction observed in plants simultaneously inoculated with the pathogens. Those plants also showed the highest disease severity in terms of percent root–rot. Thus, a manifold action plan to reduce the impact of the root-rot disease complex on chickpea crops has to be formulated.
