Effects of Heavy Metals on Plant Productivity: Source Identification and Mitigation Strategies with a Bibliometric Perspective

Abstract

On a worldwide scale, plant life, human health, and food security are under serious threats due to contamination of productive agricultural land by trace metals. Attributed from both anthropogenic as well as natural causes, heavy metals can spread through the environment in innumerable ways. Mining, abandoned mining sites, fertilizer and pesticide use, and sewage irrigation are examples of human-related factors; natural causes, in general, can include any process involving wind erosion and migration, as well as the mechanical redistribution of soil debris can affect crop health and yield when they reach dangerous concentrations. Physicochemical properties of soil and crop species, favorable or non- favorable conditions of growth of plants, toxicity of elemental composition of plants, developmental stages of crop plants, and the content of HM in soil solution are some of those factors that influence the harmfulness of HM to plant productivity. Excessive and continuous application of manure were found to have an impact on increasing the entire level of heavy metals such as CD, Zn, Cr, and Cu in soil but not Pb, Ni, and as in soil. The decomposition of organic matter, nutrient cycling & plant growth support are all made possible by these soil microbes. Heavy metals origin in soil by various researchers have also been mentioned in this review along with how they affect microbial diversity and abundance, enzyme activity, and functional activities. Further, adaptation and resistance mechanisms of microbes are reviewed. Methods for limiting heavy metal accumulation into crops, restoring contaminated land, and ensuring sustainable agricultural productivity are revisited in this review.