Day-night Differences in the Accumulation and Translocation of Ions by Tobacco Plants

Abstract

Accumulation of K42, Rb86, and Br82 during the day (6 a.m. - 6 p.m.) and during the night (6 p.m. - 6 a.m.) was measured for intact and detopped tobacco (Nicotiana tabacum) in a dark room controlled at 18[degree]C. Translocation of the isotopes to the shoot was studied for intact plants. More of each isotope was accumulated in the night than during the day and the effect was related to the period immediately prior to detopping. More of each isotope was translocated to shoots in the day than during the night. It is suggested that periodicity of exudation is regulated at the tonoplast.