Phytoextracts as Crop Biostimulants and Natural Protective Agents—A Critical Review

Excessive application of synthetic chemicals to crops is a serious environmental concern. This review suggests that some potential natural compounds can be used as alternatives and could be applied directly to plants to improve crop growth and productivity. These phytoextracts can serve as biostimulants to induce abiotic and biotic stress tolerance in different crops growing under diverse environmental conditions. The biosynthesis and accumulation of a variety of chemical compounds such as glycinebetaine, vitamins, nutrients, and secondary metabolites in some plants are of great value and an environmentally friendly cheaper source than several synthetic substances of a similar nature. The review summarizes the information regarding the potential role of different plant phytoextracts and suggests subsequent applications to modulate crop stress tolerance. Future studies should focus on the relative effectiveness of these plant-based extracts compared with their synthetic counterparts and focus on practical applications to signify sustainable practices linked with the use of natural products.