Mepiquat chloride-driven regulation in cotton in China: a review of physiological mechanisms, agronomic integration, and future trajectories

Abstract Crop chemical regulation using plant growth regulators (PGRs) represents a key strategy for achieving high-efficiency cotton production in China. This review synthesizes four decades of research on mepiquat chloride (MC), an inhibitory PGR pivotal to optimizing cotton growth architecture, stress resilience, and yield-quality parameters. We detail MC's stage-specific roles—from root development and flowering acceleration to canopy optimization and assimilate partitioning—and its mechanistic interactions with hormones (e.g., gibberellin suppression, cytokinin enhancement) under biotic/abiotic stresses. Furthermore, we conceptualize MC deployment into three evolutionary tiers: (1) symptom-guided remedial application, (2) systemic growth-stage programming, and (3) integrated management with agronomic practices. These paradigms, supported by field validation across China's cotton belts, offer a roadmap for precision regulation. Future advancements in nano-formulations, digital agriculture, and PGR synergism are discussed to unlock next-generation yield frontiers.