Biostimulants and their role in improving plant growth under drought and salinity

Biostimulants are products that reduce fertiliser requirements while also stimulating plant growth and protecting crops from abiotic stress by increasing tolerance. Biostimulants such as algal or other plant extracts, protein hydrolysates, humic and fulvic acids, and other enhanced combinations have been shown to promote further growth and stress adaptability. These outcomes consist of higher yield, enhanced nutrient absorption and utilization, increased photosynthetic activity, and tolerance to both biotic and abiotic stressors. While most biostimulants have a variety of effects on plant growth, this chapter concentrates on bioprotective effects against abiotic stress. Biostimulants have the potential to make agriculture more sustainable and resilient, as well as provide an alternative to synthetic protectants, which have proven increasingly unpopular with consumers. In this regard, this chapter seeks to discuss the specific function of biostimulants that have defensive effects against abiotic stress, but also highlights the urgent need to investigate the underlying processes that cause these benefits.