Nematicidal performance of certain organic and inorganic compounds against Meloidogyne incognita infecting okra plants

Abstract

The present study was carried out to evaluate the nematicidal activity of some organic and inorganic compounds, as well as fosthiazate as a standard nematicidefor their hatching inhibitory and juvenile mortality potential and to ascertain their role as organic amendments for the management of root-knot nematode (Meloidogyne incognita) affecting okra plants in vitro as well as in vivo conditions. Five concentrations of all chemicals were prepared. Data of in vitro studies showed a marked nematicidal and nematode hatching inhibitory activity against root-knot nematode (M. incognita). However, the nematicidal activity differed between treatments as compared to control. Fosthiazate was found as the most toxic compound against J2 of M. incognita after 24 and 48 hour exposure time as well as inhibited the egg hatching significantly after 2, 5 and 7 days of exposure. Moreover, the juvenile mortality increased with increase in concentration of chemical compounds and the exposure time. In vivo studies data showed that all treatments reduced root galls, egg-masses, number of J2 in soil, total eggs, final population and reproduction rate significantly. Meanwhile, the applied treatments exhibited enhancement in plant growth parameters and decreased the host infection by M. incognita over control. Among all the treatments Fosthiazate proved to be the best treatment while cattle manure was found as the least significant.The biochemical response of treated plants showed that infected plants with M. incognita recorded the least increase of total phenols (0.42 mg/g) and highest suppression in total proteins (10.41 mg/g), total sugars (7.86 mg/g) and reduced sugars (3.09 mg/g) as compared with untreated check. Moreover, citric acid was the most effective treatment which exhibited the highest values of total phenols (0.69 mg/g), total protein (18.08 mg/g), total sugar (17.89 mg/g) and reduced sugar (10.05 mg/g), whereas cattle manure gave the least values of total phenols (0.47 mg/g), total protein (11.70 mg/g), total sugar (9.74 mg/g) and reduced sugar (4.39 mg/g).