Release of Herbicides by Soybean Roots in Culture Solutions

Abstract

The release of 3-amino-2,5-dichlorobenzoic acid (amiben), 2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine (atrazine), isopropylm-chlorocarbanilate (chlorpropham), S-ethyl dipropylthiocarbamate (EPTC), and 3-(3,4-dichlorophenyl)-1-methoxy-1-methylurea (linuron) from excised soybean (Glycine max(L) Merr., var. Chippewa) roots following uptake of the herbicides from solutions for 1 hr was studied. Rates of release of herbicides into water were rapid with at least 30% of that taken up being released during the first 30 min. Herbicide X time and herbicide X concentration interactions were highly significant. In most instances, slow release continued for 4 hr, which was the duration of the experiment. Use of herbicide or nutrient solutions as release solutions did not significantly change the amounts of herbicides released. It was concluded that herbicide molecules released after 1 hr uptake were those that had diffused out from free space rather than those released from uptake or adsorptive sites.