Movement of Chlorine within Plants.

Abstract

A definition of "retranslocation" was established. Experiments were performed to ascertain the extent to which chloride was translocated and retranslocated in tomato and sugar beet plants. Radiochloride was applied overnight to the leaves of tomato and sugar beet plants. The plants were harvested one and 8 days after termination of such application. Radioautographs showed that some of the applied radiochloride reached all parts of the plants. More radiochlorine had been translocated from the application site 8 days after application than had been translocated one day after application. Known amounts of radioactive chloride were supplied to the roots of tomato plants in culture solutions at two levels - a deficient level and an adequate level. Plants were harvested at different times and the plant parts were assayed for radiochlorine, such assays being expressed as percentages of the total applied labeled chloride and as concentrations in [mu]g atoms per gram dry weight of tissue. It was shown that some younger plant structures obtained radiochlorine at the expense of the older leaves. This demonstrated retranslocation of chlorine as defined. Retranslocation was from regions of high chlorine concentration to those of low concentration, and was concurrent with a decrease in chlorine concentration in all plant parts.