We investigated the mercury (Hg) uptake by seedlings of rice (Oryza sativa L.) grown in solution and interactions between Hg and arsenate uptake. The results showed that increasing Hg 2+ concentrations in the nutrient solution decreased both root and shoot biomass. Hg 2+ at concentrations of 1.0 and 2.5 mg L −1 caused 50% reduction in root biomass. A 50% reduction in shoot biomass occurred at Hg 2+ concentrations of around 0.5 mg L −1 . Nevertheless, 0.5 mg As L −1 has no significant effect on plant yield. Hg accumulated in rice roots, and the Hg concentration factor in roots reached nearly 1900 at 2.5 mg Hg L −1 . The addition of As slightly increased the Hg concentration in the roots. However, As concentrations in the roots decreased significantly with increasing Hg concentration in the growth solution to 1.0 or 2.5 mg Hg L −1 . Shoot As concentrations decreased with increasing Hg concentrations in the growth solution, but increased again with further increase in Hg concentration to 2.5 mg L −1 . Possible mechanisms of Hg uptake and interactions between Hg and As in the uptake process are also discussed.

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Schisandra chinensis (Turcz.) Baill. is an important medicinal plant in northeast China. Cutting propagation is an effective method for the rapid propagation of many tree species. This research aimed to determine a suitable growing medium and appropriate root hormone type, concentration and treatment time through the utilization of different substrates and hormones to treat one-year-old branches of S. chinensis. The optimal treatment achieved a rooting rate of 60% with 225 ppm ABT and 75 ppm NAA for 2.5 h. The substrate of vermiculite/perlite = 1:1 (urea+potassium) was beneficial to the adventitious root formation, which reached 79%. The adventitious root primordium of S. chinensis originated from the junction of the xylem and cambium. ABT and NAA treatments altered the peak timing of POD, PPO and IAAO in S. chinensis cuttings. During the adventitious root formation of S. chinensis cuttings, the high endogenous IAA concentration promoted the occurrence of adventitious roots in the early stage and the lower endogenous IAA and GA3 concentrations promoted the elongation and growth of adventitious roots in the later period. Low ABA and ZR concentrations enabled adventitious root formation and elongation. An efficient cutting propagation system would enable the mass propagation of S. chinensis seedlings.

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