コマツナの成長およびタリウム含量に及ぼす土壌中タリウム濃度の影響

概要

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Since Tl is toxic for various organisms including humans and Brassica plants have a high concentration of Tl, the uptake of Tl by komatsuna from soil was investigated by pot experiment for 28 d. Tl was added at 0, 5, 10 and 20 mg kg^<-1> DW to soil which contained 0.448 mg Tl kg^<-1> DW. 1) Chlorosis was only observed on the leaves of the 20 mg kg^<-1> DW plot. 2) Yield (FW) of the shoot was nearly the same in 0, 5 and 10 mg kg^<-1> DW plots, and decreased 51% in the 20 mg kg^<-1> DW plot. Yield (DW) of the shoot in the 20 mg kg^<-1> plot was only 43% of the 0 mg kg^<-1> DW plot. 3) Tl content was 0.38 mg kg^<-1> DW in the shoots of the 0 mg kg^<-1> DW plot, and increased much by the addition of Tl. The shoots in the 20 mg kg^<-1> DW plot contained 163 mg Tl kg^<-1> DW. Some 96-99% of the absorbed Tl was translocated to the shoots. Concentration factors (CF: ratio between the content of element in plant tissue and its content in soil, calculated by a dry-Weight basis) in the 0, 5, 10 and 20 mg kg^<-1> DW plots were 0.8, 4.8, 5.7 and 8.0, respectively. 4) Tl content of the shoots in the 0 mg kg^<-1> DW plot was 0.028 mg kg^<-1> FW, which is about one-fourth of the maximum Tl content allowed in food regulated in Germany (0.1 mg kg^<-1> FW). 5 ) When Tl content in the shoots was about 150 mg kg^<-1> DW, the yield of the shoots (DW) decreased by 50%.
1999-08-05