Analysis of Animal Protein Hydrolysates as Plant Biostimulants- A Review of Literature

The pursuit of sustainable agriculture has intensified the search for effective biostimulants to enhance crop productivity and resilience. Among the various categories, protein hydrolysates (PHs) have gained significant attention for their positive effects on plant growth, nutrient efficiency, and abiotic stress tolerance. While plant-derived PHs is widely studied, this mini-review focuses on the emerging role of animal-derived protein hydrolysates (APHs) as potent plant biostimulants. Sourced from by-products of the animal processing industry (e.g., collagen, epithelial tissues, meat, and feathers), APHs are rich in peptides, amino acids, and other bioactive compounds. The review synthesizes current knowledge on the production methods of APHs, primarily through chemical or enzymatic hydrolysis, and how these processes influence their bioactive properties. We discuss the direct and indirect mechanisms of action by which APHs influence plant physiology, including the stimulation of root development, enhancement of nutrient uptake (particularly nitrogen), and modulation of key metabolic pathways and hormonal activity. Furthermore, evidence of their efficacy in mitigating various abiotic stresses, such as drought and salinity, is summarized. Finally, the abstract addresses the challenges and future perspectives for the widespread adoption of APHs, including the need for standardized characterization, a deeper understanding of their structure-activity relationship, and considerations for their integration into sustainable cropping systems, highlighting their value in a circular economy model.