Penetration, Translocation, and Metabolism of¹⁴C-Difenzoquat in Wild Oat and Barley

Abstract

Foliar penetration of14C-difenzoquat (1,2-dimethyl-3,5-diphenyl-1-H-pyrazolium), in the presence of a surfactant, into both wild oat (Avena fatuaL.) and barley (Hordeum vulgareL. ‘Conquest’), was rapid and continued at a nearly constant rate for 72 hr, the maximum time period studied; 93 and 84% of the applied dose was absorbed by the leaves of wild oat and barley, respectively. Added surfactants at 0.01% to 0.3% and high relative. humidity (RH) greatly enhanced the penetration of the herbicide into wild oat. An increase in temperature from 10 to 30 C resulted in a large increase in penetration. Commercial formulations of bromoxynil (3,5-dibromo-4-hydroxy-benzonitrile) + MCPA {[(4-chloro-O-tolyl)oxy] acetic acid} (1:1, w/w), 2,4-D[(2,4-dichlorophenoxy)acetic acid] ester and barban (4-chloro-2-butynylm-chlorocarbanilate) markedly increased the penetration of14C-difenzoquat into wild oat. Amine formulation of 2,4-D, on the other hand, had no effect on penetration. Foliarly-applied14C-difenzoquat rapidly translocated mainly in the acropetal direction. Most of the absorbed14C, however, was accumulated in the treated area and a few centimeters above the treated area. There was some basipetal movement, and 24 hr after treatment14C was detectable in the roots. Root uptake of14C-difenzoquat was very rapid, but upward movement of14C was slight, and even 24 hr after treatment most of it was retained by the roots. Chromatographic analysis of plant extracts up to 15 days after treatment with14C-difenzoquat revealed no evidence of difenzoquat metabolism by wild oat, barley, and wheat (Triticum vulgareL. ‘Thatcher’). The selective action of difenzoquat in wild oat and barley cannot be accounted for by differences in its foliar penetration, translocation, or metabolism in these species.

Modeling Xenobiotic Uptake and Movement: A Review

“…The model ERMESSE can also be useful in the evaluation of the effects of adjuvant on xenobiotic absorption (Table 4). Indeed, when the effect of the adjuvant octoxynol on the absorption of difenzoquat was simulated, it appeared that the model predictions were quite close to the actual data observed by Sharma et al (132). These data showed that the model ERMESSE can accurately predict xenobiotic uptake when the compound is applied with or without an adjuvant.…”

Influence of environmental factors on glyphosate efficacy when applied to Avena fatua or Urochloa panicoides

“…Higher temperatures are likely to be more favourable for the absorption and translocation of glyphosate, as has been seen in Cynodon dactylon (L.) Pers. (Bermuda grass) (Jordan, 1977) or in A. fatua with difenzoquat (Sharma et al, 1976). In contrast to the response noted at ®eld capacity, glyphosate ecacy decreased under the reduced soil moisture conditions as the temperature increased.…”

Influence of temperature and light intensity on absorption, translocation, and phytotoxicity of fenoxaprop-ethyl and imazamethabenz-methyl in Avena fatua

“…In A. fatua, the translocation of flamprop and difenzoquat was also reduced at low temperatures (Jeffcoat et al 1977, Sharma et al 1976). Coupland (1989a) found that low temperature decreased the deesterification of fluazifop-butyl.…”

“…greater under higher temperature conditions (Grafstorm and Nalewaja 1988, Kells et al 1984, Sharma et al 1976, Wills 1984, Wills and McWhorter 1983. The influence of temperature on herbicide translocation and phytotoxicity varied (Blair et al 1983, Coupland 1986, Devine et al 1983, Grafstorm and Nalewaja 1988, Kells et al 1984, Klevorn and Wyse 1984, Morrison 1983, Nalewaja and Woznica 1988, Smeda and Putnam 1990, Wills 1984, Wills and McWhorter 1983.…”