The multidimensional regulation roles and mechanisms of calcium in fruit quality

Calcium (Ca²⁺), a dual-functional mineral that serves both as an essential structural factor and a signaling molecule, plays a critical role in regulating fundamental physiological processes in plants, including development, stress response, and fruit quality traits. However, a comprehensive and systematic summary of calcium's regulatory functions in fruit quality is still lacking. This review aims to clarify the pivotal roles of calcium in regulating key fruit quality attributes, including external traits such as morphology and coloration; internal nutritional properties, such as flavor-related metabolites and bioactive compounds; and physiological disorders such as cracking, softening, browning, chilling injury, blossom-end rot, water core, and bitter pit. Considering its diverse regulatory functions, genetic manipulation of Ca²⁺ signaling pathways and the application of nano-calcium formulations offer promising strategies for improving fruit yield and quality in commercial production systems. This review further outlines the underlying mechanisms through which calcium influences fruit quality and suggests future research directions to address existing knowledge gaps.