Thesis (M.Sc.)--Chulalongkorn University, 2002

The purposes of this study were to study and compare the accumulation of arsenic in Colocasia esculenta (L.) Schott (taro and wild taro) among different concentrations of arsenic in soil and study the efficiency of ethylenediaminetetraacetic acid (EDTA) solution to enhance the accumulation of arsenic in both plant species. The plants were planted in the experimental pots and amended with disodium hydrogen arsenate (Na2HAsO4.7H2O) solution with 4 different concentrations (control, 100, 200, and 400 mg As/kg soil). Ethylenediaminetetraacetic acid (EDTA) solution 5 mmol/kg was apply to the soil surface 2 weeks after amending with disodium hydrogen arsenate (Na2HAsO4.7H2O) solution. The plants were harvested and cut to sample every 20 days for 100 days and analyzed for total arsenic accumulation in 4 parts that are corm, roots, petioles, and laminas. The results indicate that both plants could growth well in concentration of 100 and 200 mg As/kg soil. Amount of arsenic accumulated in root was more than in corm, petiole, and lamina, respectively. And the research shows that the accumulation of arsenic in both plants can be enhanced through the application of EDTA to the soil. The maximum arsenic accumulations in plants were 40.34 mg for taro and 46.79 mg for wild taro in concentration of 400 mg As/kg soil.