Absorption and Translocation of Terbutryn and Propazine

Abstract

The absorption and translocation patterns of terbutryn [2-(tert-butylamino)-4-(ethylamino)-6-(methylthio)-s-triazine] and propazine [2-chloro-4,6-bis(isopropylamino)-s-triazine] were determined in wheat (Triticum vulgareVill. ‘Kaw’) and sorghum (Sorghum bicolorL. ‘RS 612’). Bioassay studies showed sorghum to be tolerant and wheat susceptible to terbutryn. Absorption and translocation of uniform14C-labeled terbutryn from 1 to 24 hr after initial treatment showed the roots of sorghum and the foliage of wheat to be the major sites of radioactivity accumulation. Foliage was the major site for propazine accumulation with both plant species. Thin-layer chromatography of extracts from terbutryn-treated plants showed that sorghum contained a higher percentage of metabolic breakdown products in the foliage than did the root systems, and wheat contained a high percentage of intact terbutryn in the foliage and roots. High temperature (32 C) enhanced translocation of terbutryn and propazine in both sorghum and wheat. The susceptibility of wheat and sorghum to terbutryn appears to be correlated with a combination of the factors of accumulation within the foliage of the plant and the ability to degrade the terbutryn molecule.