Multitracer study on uptake of elements by turnip

Abstract

The absorption selectivity of radioactive elements for turnip seedlings have been determined by a multitracer technique. The value of selectivity was calculated using the total amount of a radioisotope absorbed by a plant during the experimental period, the amount of transpiration, and the initial concentration of the isotope in a nutrient solution. The detailed procedures of the experiments including the preparations of a nutrient solution and the hydroponical cultivation of turnip seedlings were described. It was found that the selectivity of elements was in general decreased with the increase of the concentration of nutrient solutions. The differences of selectivity between alkali elements and alkaline earth elements for the leaves and roots were discussed. It was indicated that many elements which were not regarded as useful elements for the plant growth were retained on the roots without their translocation to the leaves, excluding Re exhibiting a contrasting result.

カブの苗に対する放射性元素の吸収選択性を多重トレーサ手法を用いて測定した。選択性の値は、実験期間中に植物が吸収した放射性同位体の総量、蒸散量、および栄養液中の同位体の初期濃度から算出した。栄養液の調製とカブの苗の水耕栽培を含めた実験の手順を詳細に記述した。栄養液の濃度の上昇に伴い一般的に元素の選択性が低下することが分かった。葉と根茎に対するアルカリ元素とアルカリ土類元素間の選択性の違いを論じた。対照的な結果を示したReを除いて、植物の成長には不要な元素と見なされている元素の多くは根茎に残留し、葉への転流をしないことが分かった。