Abstract
Biostimulants have shown great promise for sustainable agriculture and horticulture in general. Protein hydrolysates are biostimulants obtained through chemical and enzymatic hydrolysis of animal and plant proteins. The current study provides a summary of the effects of protein hydrolysates (PHs) on morphology, physiology, growth, yield, and stress tolerance of horticultural crops. Additionally taken into account are the impacts of PHs on plant growth and root development, their role in stimulating hormone-like activity, and their capacity to improve nutrient uptake and assimilation. These effects are explained by the high amino acid content of PHs, which can influence chlorophyll synthesis, photosynthetic efficiency, and enzyme activity. Numerous studies demonstrate that by boosting osmolyte accumulation and antioxidant activity, PHs can mitigate abiotic stressors such as drought, salinity, and temperature extremes. Additionally, PHs can affect microbial activity in the rhizosphere and bulk soil, thereby enhancing microbial interactions. For effective administration, PHs can be applied as foliar sprays, root drenches, or through fertigation. PH application depends on plant species, formulation, application rate, and response. More information is needed on signaling pathways, metabolic processes, and biochemical mechanisms to enhance plant-specific responses.
Keywords: biostimulants, protein hydrolysates, amino acids, stress resistance