Effect of sulphate nutrition on arsenic translocation and photosynthesis of rice seedlings

The effect of sulphate nutrition on arsenic (As) concentration, photosynthetic and chlorophyll fluorescence parameters of rice was investigated in hydroponically grown rice seedlings (Oryza sativa L.), using three sulphate levels (1.8 μM, 0.7 mM, or 1.5 mM). The results showed that sulphate deficiency decreased As accumulation in root, but increased the translocation of As from root to shoot. Sulphate deficiency reduced maximum quantum yield (Fv/Fm), minimum fluorescence and electron transport rate (ETR) of a dark-adapted leaf. Compared with low sulphate treatments (1.8 μM), significant increases were observed in the parameters of rapid light curves, rETR_max and I _k of photosystem I (PSI) and photosystem II (PSII) of rice grown in the high sulphate treatments (1.5 mM) regardless of As additions. Therefore, an adequately high sulphate supply may result in less As translocation from root to shoot, and protecting the reaction pathways of PSI and PSII of rice seedlings grown in higher As-contaminated medium.