Water deficit induced oxidative damage in tea (Camellia sinensis) plants.

When the tea (Camellia sinensis) leaf water potential was -1.1 MPa (Moderate water deficit), there was 58% inhibition of photosynthesis accompanied by increased zeaxanthin, malondialdehyde, oxidized proteins and superoxide dismutase activity. When the leaf water potential was -2MPa (severe water deficit), there was nearly complete inhibition of photosynthesis apart from a decrease in chlorophylls, beta-carotene, neoxanthin and lutein. Water deficit at this level caused further conversion of violaxanthin to zeaxanthin, suggesting damage to the photosynthetic apparatus. There were consistent decreases in antioxidants and pyridine nucleotides, and accumulation of catalytic Fe, malondialdehyde and oxidized proteins. It is inferred that, in tea plants, the increase in catalytic Fe and the decrease in antioxidant protection may be involved in the oxidative damage caused by severe water deficit, but not necessarily in the incipient stress induced by moderate water deficit.