| Summary: | 碩士 === 國立嘉義大學 === 農藝學系研究所 === 105 === For assessing the eco-toxicological risk and food safety, we needs more knowledge about the Cd accumulation by plant from soil. Cadmium ions would compete for the same trans-membrane carriers with most of the essential cations (e.q. K+, Ca+, Mg2+ ect.). The objectives of the present study are to investigate effect of Ca, Mg and K on two rice cultivars, Taichung Sen 10(TCS10) and Taiken 9 (TK9), under Cd stress. The 10% modified Hoagland’s solution was used as the background hydroponic solution, contain different Ca backgrounds (i.e. 0.5, 1, 5, 10 mM), Mg backgrounds (i.e. 0.5, 1, 2, 4 mM) and K backgrounds (i.e. 1, 3, 5, 10 mM). Exposure under Cd treatment by 0, 5, 10, 20, 50 mM for 7 days. The results revealed that Cd reduces elongation of root in both cultivars. In the treatment of each group, TK9 have more root elongation than TCS10. When the concentration of calcium, magnesium and potassium increased, the active concentration of cadmium affected and mitigated the toxicity of cadmium on rice roots. Calcium, magnesium and potassium can increase the concentration of EA50. Calcium, magnesium and potassium have a greater reduction in cadmium toxicity to TK9 than TCS10. Calcium and magnesium can reduce cadmium bio-concentration factor, BCF, in rice seedlings to reduce cadmium concentration and reduce cadmium accumulation. Determination of active oxidized substances (ROS) and antioxidant enzyme activity. Calcium and magnesium increase the activity of SOD and CAT, accelerate the decomposition of ROS, relieve cell damage. In addition, MDA is the degree of lipid peroxidation. Calcium and magnesium can reduce the damage caused by cadmium, but Potassium is no significant difference with the control group. This is consistent with the results of cadmium absorption. Calcium and magnesium may reduce the absorption of cadmium and thus reduce the amount of reactive oxygen species. Calcium and magnesium may also increase the activity of antioxidant enzymes and reduce cadmium on the toxicity of rice seedlings.
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