Evaluation of nematicidal potential of neem sawdust against Meloidogyne arenaria on eggplant

Abstract

The present study was conducted to evaluate the impact of amending soil with decomposed neem (Azadirachta indica) sawdust at different concentrations (0-100%) against different inoculum levels (0-4000) of root-knot nematode (Meloidogyne arenaria) infecting the eggplants. Various physico-chemical properties of the soil increase as the concentration of decomposed neem sawdust (NSD) in the field soil increases. Nevertheless, the nitrogen content of the soil decreased with a progressive fluctuation in NSD. Lower levels (10-30%) of NSD, with and without different inoculum levels, improve the plant growth and photosynthetic pigment content significantly compared to controls (plants with uninoculated soil) as well as inoculated plants. The maximum improvement in the growth and photosynthetic pigments was recorded at 30% NSD soil amendment and this was continuously effective against all the nematode inoculum levels. At higher levels of NSD (40-100%), all the studied growth and photosynthetic parameters were decreased gradually to control and a similar reductional trend was also observed on nematode inoculated eggplants. On root-knot nematode reproduction, NSD at all levels progressively suppressed the number of egg masses but enhanced the number of galls only up to 30%. Galling was, however, totally absent in 70% and onward dust treatments of eggplants. Conclusively, NSD suppressed plant growth and photosynthetic pigments along with nematode buildup beyond 40% amendments. Thus, lower NSD levels (up to 30% amendments) will be recommended as growth and photosynthetic pigments supplement to eggplants, which also have nematicidal potential against egg masses of nematodes.