Abstract: A pot experiment was conducted to study the distribution of Hg forms in soil and the distribution and accumulation characteristics of Hg in rice (Oryza sativa L.) plant during its various growth stages under different concentrations of soil Hg. The main Hg forms in the soil were in the order of organic bound > residual >> oxidizable >> dissoluble and exchangeable ≈ specifically adsorbed. During rice growth season, the Hg in soil presented a transformation trend from residual to organic bound, and the organic bound Hg occupied 61.7% of the total Hg, being the most important existing form of Hg in soil. The Hg concentration in different organs of rice was in the order of root > leaf > stem > ear > grain. The Hg concentrations in rice root, stem, and grain were significantly positively correlated with the concentrations of all the Hg forms in soil. However, at the late growth stages of rice, the leaf Hg concentration had less correlation with soil Hg concentration, indicating that the exchange between leaf Hg and atmospheric Hg played a major role, and changed the Hg accumulated status. With the increase of soil Hg concentration and the extension of rice growth phase, the Hg binding capacity of rice root increased gradually, and the cumulative amount and the proportion of root Hg increased, while the accumulation amount of stem and leaf Hg was relatively stable.

Key words: state transition, LHCⅡ phosphorylation, photosystem, NPQ.