Shivani Mahra, Sobhitha Mathew, Kritika Singh, Kavita Tiwari, Sneha Tripathi, Shivesh Sharma
The increasing demand for sustainable and precision-driven agricultural practices has increased the interest in biopolymer-based nanoparticle systems for the delivery of plant growth regulators (PGRs). Although there have been advancements in the development of nanoparticles as carriers for plant growth regulators, there is still no systematic understanding of what role nanoparticles play in either protecting or controlling the delivery of hormone-based PGRs. Among these, the plant hormone salicylic acid (SA) is a key component of plants response to various stimuli (e.g., growth and defense against biotic stress, such as insects and pathogens) and in how they adapt to environmental stresses (e.g., temperature and/or light). The practical use of SA is limited by its instability when exposed to certain environmental stresses (e.g., high temperatures, UV light, or changes in pH). This review summarizes the most recent advances in the use of biopolymers for nanoencapsulation of salicylic acid, with an emphasis on the benefits associated with the use of these delivery systems to maintain the stability of SA, reduce degradation and leaching losses, and control the release and delivery of SA during application. In analyzing the most commonly used encapsulation materials and describing their mechanism of action to achieve the highest yield in crops through the application of plant hormones, this review demonstrates the potential for the combination of nanotechnology with plant hormone management. In addition, it highlights what gaps exist in current knowledge and encourages the development of novel, innovative approaches to implement precision and eco-efficient crop management practices.