Vol. 54—2000 - NorthEastern Weed Science Society

ABSORPTION, TRANSLOCATION AND METABOLISMOF ISOXAFLUTOLE IN
YELLOW FOXTAIL (Setaria luteseens).
S. Kushwaha" and P. C. Bhowmik'
ABSTRACT
Ourpreliminarystudieshaveshownyellow foxtail [Setaria lutescens (Weigel)
Hubb.] to be less sensitive to isoxaflutole [5-cyclopropyl-4-(2-methylsulphonyl-4­
trilluromethylbenzoyl) isoxazole]. Experimentswere conducted to study the extent of
absorption,translocationof foliarapplied,andmetabolismof rootappliedisoxaflutolein
yellow foxtail. Ring labeled "C isoxallutole was applied to three-leaf seedlings in half
strength Hoagland solution. Plants were harvested 3, 6, 12,24, 48, 72, 96 and 120 hours
aIler treatment. Plants were sectioned in treated leaf, leaves above treated leaf, leaves
below treated leaf androots.Theamountof '''cisoxaflutolein variousplantparts was
determined by digesting the plant samples in biological oxidizer. By the end of 48 h,
foliar absorption reached to the maximum of 67.4% of total applied radioactivity. Treated
leaf, leaves above treated leaf, leaves below treated leaf and roots had 45.0, 6.4, 15.6 and
0.5%radioactivityrespectively.Formetabolismstudyof root appliedisoxaflutole,plants
were harvested at 72 and 168 h. Plant extract was subjected to thin layer chromatography.
Thetotalradioactivitywas identifiedas isoxaflutole,diketonitrilemetabolite,unknown
metabolite A and benzoic acid, and the distribution was 4.6, 64.5, 7.3 and 17.9'/0at 72 h,
and 4.1,55.8,9.5 and 24.2% at 168 h, respectively.
'Graduate Research Assistant and Professor of Weed Science, Department of Plant and
Soil Sciences, University of Massachusetts, Amherst, MA 01003.
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