Can vermicompost and biochar control Meloidogyne javanica on eggplant?

Abstract

Summary The root-knot nematode, Meloidogyne javanica, is the most damaging species of plant-parasitic nematodes in eggplant cultivation in Iran. We studied the effect of pistachio and date palm biochars, vermicompost and a mixture of each of these biochars with vermicompost on M. javanica. To investigate the effect of these organic materials on survival, hatching and attraction of the second-stage juvenile (J2) towards the root, bioassays were performed in the laboratory using extracts of organic material. Vermicompost extract increased J2 mortality and decreased hatching and the number of J2 attracted to the eggplant roots. However, either type of biochar alone or mixed with vermicompost did not cause J2 mortality, nor did they inhibit hatching and attraction of J2 towards the root. To determine the effect of organic matter on J2 invasion and reproduction, pot experiments were performed in a completely randomised design with four replications in the glasshouse. Vermicompost reduced the number of J2 that penetrated the roots, number of egg masses and the final population of M. javanica eggs and J2. The suppressing effect of vermicompost might be attributed to the release of toxic compounds such as ammonium and improved soil nutrient and plant growth, leading to plants more tolerant to nematode damage. Pistachio and date biochars alone or combined with vermicompost had no adverse effect on the nematode reproduction compared to non-treated soil. Both types of biochar reduced the suppressing effect of vermicompost, most probably due to the absorbance of suppressive compounds in vermicompost by the high surface area of the biochar.