Creative Commons

In the present era, the concern regarding heavy metal pollutants in soil, water, and air has escalated significantly. This apprehension stems from the fact that heavy metals like Cadmium (Cd), Arsenic (As), Lead (Pb), among others, have the capacity to be absorbed by plants and eventually enter the human body through the food chain. These heavy metals pose serious threats to plants, impeding their growth and reproductive capabilities. In response, scientists are actively seeking solutions to shield plants from such detrimental effects. Various substances such as Silicon (Si), Sulfur (S), biochar, melatonin, chitosan, and notably, Selenium, have been tested and demonstrated effectiveness in this protective role. Selenium, a metalloid renowned for its antioxidant properties, plays a crucial role in aiding plants combat both biotic and abiotic stresses. The primary objective of this review is to comprehensively gather and analyse a substantial body of studies conducted between 2020 and September 2023 that focus on the application of Selenium in plants to mitigate heavy metal stress. Our survey encompassed 48 pertinent studies. Some studies individually applied Selenium and compared its efficacy with alternative substances, while others explored its combined application with other materials to assess potential synergistic effects. Categorizing these studies based on various criteria enabled us to uncover significant connections among them. The findings underscore a predominant focus on Cadmium as the most extensively studied heavy metal, followed by Arsenic and Lead. Additionally, our analysis highlights the prevalence of specific plant species, particularly those belonging to the Poaceae and Brassicaceae families (such as rice, wheat, and raphanus), in these studies. Pot experiments emerged as the dominant trial method for Selenium application, equally implemented through fertigation, soil/medium, and foliar application. Selenite was the most frequently employed form of Selenium, often utilized in Selenium Nanoparticles (Se NPs). Selenium was commonly combined with organic amendments like biochar and vermicompost. Furthermore, the review delineates that the primary mechanisms underlying Selenium's effectiveness against heavy metal phytotoxicity are associated with plant growth promotion, activation of plant defense systems, and alteration of soil properties. To enhance future research endeavors, emphasis should be placed on conducting more open field experiments and expanding investigations into the synergistic actions of Selenium with other substances across various significant plant species.