Harnessing plant growth regulators and biostimulants for resilient and productive agriculture

Agricultural systems face increasing pressure to sustain productivity under intensifying climate variability, soil degradation, and resource limitations. Plant growth regulators (PGRs) and biostimulants have emerged as complementary tools capable of enhancing plant performance beyond conventional fertilization strategies. However, existing literature largely treats these inputs independently, limiting a mechanistic understanding of their interactive potential. This review newly delivers an integrated, cross-disciplinary synthesis that connects hormonal regulation (PGRs) with microbial and metabolite-mediated stimulation (biostimulants) across physiological, molecular, and stress-adaptation pathways. We comparatively analyzed how PGRs regulate hormone signaling, gene expression, and plant architecture, while biostimulants enhance nutrient-use efficiency, rhizosphere interactions, antioxidant systems, and soil functionality. Special emphasis is placed on their roles in mitigating drought, salinity, lodging, heavy metal toxicity, and postharvest losses. By identifying critical knowledge gaps including hormone–microbiome crosstalk, dose optimization, formulation standardization, and long-term ecological impacts, this review provides a structured framework for their strategic integration. Looking forward, advances in omics technologies, precision agriculture, and nano-enabled delivery systems are expected to refine targeted applications and improve consistency under field conditions. Collectively, this synthesis positions PGRs and biostimulants as synergistic tools for climate-smart, resource-efficient, and sustainable agricultural intensification.