Enhancing heavy metal stress tolerance in plants through vermicompost-powered remediations

Abstract

Vermicompost (VC), a nutrient-rich mixture made from decomposing agricultural or food waste and bedding materials, is produced by various species of earthworms, primarily white worms and red wigglers, transforming organic waste into a humus-like substance. Soil exhibits improved bulk density, water retention ability, porosity, and aeration after being treated with VC. It also improves soil's chemical qualities including organic and pure matter, pH, and electrical conductance and contains essential nutrients and plant growth promoters like phytohormones, enzymes, and other beneficial microbes. Contamination of land by metals such as lead is a serious problem that affects soil health, plant growth, farm productivity, and food security. Sensitive plants growing in metal polluted soils exhibit altered metabolism, reduced growth and biomass production, deteriorated quality and low yield. In response to this, environmentally friendly and sustainable remediation strategies are becoming increasingly important. Plants possess various intricate and multifaceted systems to combat heavy metals (HM) stress, involving molecular, biochemical, physiological, and ecological interactions. These mechanisms include processes such as chelation, transport, sequestration, detoxification of metals in the plant's vacuole, reduced metals absorption and immobilization and the release of enzymes, cellular and root exudates. Meanwhile, VC has evolved as a reliable solution for alleviating HM stress in plants. It enhances soil health and quality and while strengthening plants'natural defence mechanisms against metal toxicity. This comprehensive review discusses the emerging significance and mechanisms of VC for metal stress tolerance in mature plants, underlining the present knowledge gaps and future research.