A Review of Phosphorus Nutrition and Quality Regulation in Tea Plants (Camellia sinensis)

Phosphorus (P) availability is a primary constraint on tea (Camellia sinensis) production in acidic soils, where the majority of P is immobilized as insoluble Fe–P and Al–P complexes. This review synthesizes current understanding of the tea plant P nutrition chain—from soil P cycling and microbial mobilization to root uptake, systemic signaling, and ultimately the regulation of quality-related metabolism. Recent molecular studies in tea have identified several P-responsive regulatory modules; however, many mechanisms remain based on a limited number of cultivars and controlled experimental systems. Phosphorus availability can influence the relative accumulation of nitrogen-containing and phenylpropanoid-derived quality metabolites; however, the direction and magnitude of these responses depend on genotype, P supply level, developmental stage, and environmental conditions. A universal theanine–catechin trade-off cannot yet be generalized across tea germplasm. A distinctive P–Al coadaptation mechanism enables tea plants to thrive in acidic soils, where low Al concentrations stimulate root growth and enhance P acquisition, further linking soil chemistry to quality outcomes. We propose a research roadmap integrating molecular characterization, breeding, and environmental management to translate mechanistic understanding into sustainable P management for tea production.