Exogenous application of biostimulants and Cd stress tolerance

Cadmium (Cd) contamination in natural resources and its prominent and inevitable position in the food chain is a serious concern. It poses detrimental impacts on all the living organisms but plants are more susceptible to the presence of contaminants such as Cd because of being rooted in a fixed spot. Cd stress leads to impaired growth of the plants by reducing germination, disturbed mineral nutrition, water imbalances, oxidative stress, and inhibition of enzyme activity thereby disturbing potential physiological processes and declining plant growth and economic traits. Therefore the plants have to withstand the Cd toxicity in environmental sources and develop tolerance against Cd stress. To enhance the tolerance of plants against Cd stress, the role of biostimulants has been greatly acknowledged by researchers as they are promising candidates for sustaining the growth of plants under different stress conditions including heavy metal stress. Biostimulants tend to enhance the plants’ tolerance by activating several mechanisms such as improving ion homeostasis, enhancing antioxidant capacity of plants that scavenge oxidative radicals, and improving the growth status of plants. Research has been carried out using several biostimulants such as micro-organisms including rhizobacteria, algae and fungi, phytohormones, and other plant-derived biostimulants and testing their efficacy in inculcating Cd stress tolerance in plants.