Exogenous application of biostimulants for As stress tolerance in crop plants

Arsenic (As) is a nonessential toxic metalloid existing in two different inorganic forms: arsenite As (III) and arsenate As (V) which cause hindrance in plant developmental processes and are hazardous to human beings. As contamination is a major environmental issue as it stimulates physiological and metabolic dysfunctions, for instance, nutrient and redox imbalance, rate of photosynthesis, and membrane integrity, ultimately leading to reduced crop yield. Plants show detoxification processes to overcome As toxic effects by effluxing excess metal ions through metal transporters, accumulating As in the vacuole, and producing antioxidant enzymes. In recent times, the exogenous application of various biostimulants such as hormones, antioxidants, osmolytes, and others is being explored to combat As-mediating injuries to crop plants. These compounds are effective in improving seed germination, antioxidant enzyme activity, plant biomass, and overall growth of the plants. The objective of this chapter is to provide recent knowledge on the biostimulants hallmarks to alleviate As stress in crop plants.