Effects of vermicompost water extract prepared from bamboo and kudzu against Meloidogyne incognita and Rotylenchulus reniformis

Potential of vermicompost extract in enhancing the biomass and bioactive components along with mitigation of Meloidogyne incognita-induced stress in tomato

Increasing inorganic fertilizer and pesticide use has been linked to increased health risks for humans and cattle, as well as substantial water and soil contamination. In recent years, vermicomposting has shown to be a viable alternative to chemical pesticides. Vermicompost and vermicompost products such as extract and leachate assist plants in a number of ways. According to recent studies, vermicompost extract (VCE), when used as a supplement, is thought to work as a growth and stress tolerance booster for plants. These liquid supplements also help to suppress a range of pests, such as root knot nematodes. In the present study, neem- and cattle dung-based vermicompost extracts of different concentrations (0, 20, 40, 60, 80 and 100%) were prepared and used for their application against nematode infection in tomato seedlings under laboratory conditions. Apart from its antagonistic action against Meloidogyne incognita, the influence of VCE on plant growth was investigated by analyzing its morphological characteristics in tomato seedlings infected and uninfected with M. incognita. Seeds were pre-soaked in VCE for the seed priming process before being allowed for germination. After 10 days of nematode inoculation, biochemical parameters like protein content, activity of antioxidative enzymes, non-enzymatic antioxidants, stress indices, photosynthetic pigments, proline content and secondary metabolites were also analyzed. The results revealed that neem-based VCE was fatal to second-stage juveniles, with an 82% mortality rate following exposure to the highest dose. When eggs were exposed to 100% VCE, 33.8% of hatching was suppressed, indicating that VCE had an antagonistic effect on nematode egg hatching. Further, all the morphological and biochemical parameters were significantly enhanced in VCE-treated tomato seedlings as compared to untreated seedlings. Stress indices were also found to be significantly lowered by the VCE treatments in the infected plants. The effect of VCE on seedling growth and physiology was shown to be concentration dependent. As a result, the current findings show that VCE has the potential to be used as a plant growth accelerator as well as an environmentally friendly biocontrol agent against nematode pathogenesis in tomato plants.

Combined effects of vermicompost and vermicompost leachate on the early growth of Meloidogyne incognita stressed Withania somnifera (L.) Dunal

Roots of Withania somnifera, an important medicinal herb, are prone to the infection of Meloidogyne incognita (a root parasitic nematode). The infection lowers the quality and quantity of plant material and poses a challenge in crop cultivation and obtaining desirable yield. In the present study, in vitro inhibitory activity of vermicompost leachate (Vcom-L) was assessed against % hatch and survival of M. incognita in a 96 h assay. Then, Vcom-L was used as soil supplement in combination with vermicompost (Vcom) to evaluate their nematode inhibitory and stress alleviating effect in W. somnifera, in a pot experiment. Root galling intensity and growth performance of nematode-stressed W. somnifera raised from seeds pre-soaked in distilled water (DW), Vcom-L, vermicompost tea (Vcom-T) and different dilutions of Vcom-L were assessed. We observed 79% suppression of egg hatching and 89% juvenile (J2) mortality after 96 h compared to control, at 100% concentration of Vcom-L. Significant reduction in gall formation with increase in growth parameters of seedlings was observed after combined application of Vcom (60% or 100%) + Vcom-L and was evident as enhancement in seedling biomass and contents of chlorophyll and protein. However, proline, total phenolics and malondialdehyde (MDA) content declined significantly in these combinations compared to the control (0% Vcom). Activity of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidise (APX), guaiacol peroxidise (GPX) and glutathione reductase (GR) declined with Vcom as well as Vcom + Vcom-L and corresponded with decline in the accumulation of reactive oxygen species in leaves. Further, 1:5 and 1:10 dilutions of Vcom-L in combination with Vcom (60%) proved beneficial in mitigating the nematode-induced stress in W. somnifera. Present results showed the potential of Vcom and Vcom-L in standardised combination as an effective strategy in controlling the pathogenicity of M. incognita in medicinal plants such as W. somnifera.