Root-uptake of ¹⁴C derived from acetic acid by root vegetables

¹ Office of Biospheric Assessment for Waste Disposal, National Institute of Radiological Sciences, 263-8555 Chiba, Japan
² Graduate School of Pharmaceutical Sciences, Chiba University, 263-5522 Chiba, Japan
³ Graduate School of Horticulture, Chiba University, 271-8510 Matsudo, Japan

Abstract

Sand culture using radish (Raphanus sativus L.) and hydroponics using carrot (Daucus carota L.) were conducted to examine root-uptake of carbon and its assimilation in the form of ¹⁴C-acetic acid. ¹⁴C-acetic acid (1, 2-¹⁴C, radioactivity: 74 kBq) was added to each pot. Radishes were grown under the dark conditions or the light conditions for 24 h. Carrot were grown under the light conditions after ¹⁴C-acetic acid addition (radioactivity: 19 kBq). The ¹⁴C radioactivity in each plant part was determined. The distribution of ¹⁴C in the plants was visualized using autoradiography. For a comparison, autoradiography was also done using ²²Na. The results indicated that the root vegetables absorbed ¹⁴C through the roots and assimilated it into the shoots and edible parts. However, the amount of ¹⁴C-acetic acid absorbed by plants through the roots was considered to be very small. Absorption and assimilation of ¹⁴C seemed to be carried out not because of uptake of ¹⁴C-acetic acid but because of uptake of ¹⁴C in inorganic forms with very low concentration. ¹⁴C dominantly transferred to the plant parts where were physiologically active. ¹⁴C movement in the plant did not have a close relation to water movement unlike ²²Na movement.