Estimation of phloem flow velocity under cadmium stress using Positron Emitting Tracer Imaging System (PETIS)

Abstract

We have performed to estimate phloem flow velocity with the Positron Emitting Tracer Imaging System (PETIS), a noninvasive measurement device. ¹¹CO₂ was supplied to leaves of rice plants and the translocations of ¹¹C-photoassimilates were monitored using PETIS. We have developed an analytical program to estimate the phloem flow velocity from PETIS data by determining the arrival time of ¹¹C-photoassimilates to the basal part of shoot. This method was applied to a PETIS experiment testing plant response to cadmium toxicity. As a result, the phloem flow velocities in the cadmium-treated plants were estimated to be slower than those of control plants.