The Effect of Urea on Atrazine Uptake from Soil

Abstract

An application of urea to the soil of potted tomato plants (Lycopersicon esculentumMill. ‘John Baer’) increased the translocation of atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine] to the shoots of the plants. The rate of uptake of atrazine was more closely related to the rate of transpiration than it was to the rate of stump exudation or root pressure. The presence of urea did not change the metabolism of atrazine by the plants. Over the range of xylem flows from 12 ml/24 h in detopped roots (root pressure) to 211 ml/24 h in intact plants (transpiration) the concentration of atrazine in the xylem stream was approximately the same suggesting that the uptake mechanism tends to maintain a constant concentration of atrazine in the xylem stream.