Antioxidant system of tea (Camellia sinensis) leaves in response to phosphorus supply

Self-rooted, 10-month-old, uniform tea [Camellia sinensis (L.) O. Kuntze cv. Huangguanyin] trees were supplied for 17 weeks with 0, 40, 80, 160, 400 or 1,000 μM phosphorus (P). Thereafter, plant growth, leaf malondialdehyde (MDA), antioxidant enzymes and metabolites were measured to determine how antioxidant system functions to protect P-deficient leaves from photo-oxidative damage. Whole plant dry weight increased as P supply increased from 0 to 160 μM, and then kept unchanged with further increasing P supply. Phosphorus-deficient leaves displayed lower or similar activities of superoxide dismutase, ascorbate peroxidase, monodehydroascorbate reductase, dehydroascorbate reductase, glutathione reductase and catalase and contents of ascorbate and reduced glutathione depending on the degree of P-deficiency and enzyme species, but P supply did not significantly affect leaf MDA content. In conclusion, the antioxidant system in P-deficient leaves provides considerable protection to them against photo-oxidative damage.