Differences in Absorption, Translocation and Metabolism of Azimsulfuron between Rice (Oryza sativa) and Flat Sedge (Cyperus serotinus)

Abstract

Abstract:Azimsulfuron (DPX-A8947) is a new selective sulf onylurea herbicide used in rice for control of annual and perennial broadleaf weeds and sedges. We investigated the mechanism of selectivity by comparing the behavior of this herbicide in rice with that of the sensitive weed, flat sedge (Cyperus serotinus) using 14C-azimsulfuron.Azimsulfuron afforded high selectivity between rice and C. serotinus in the growth response studies by a hydroponic solution method. Studies of absorption and translocation indicated that the differential sensitivities of rice and C. serotinus to azimsulfuron are not due to its differential absorption and translocation from their subterranean parts. In metabolism studies, rice metabolized azimsulfuron very rapidly in its shoots and roots, while C. serotinus metabolized it very slowly in its shoots, roots and tubers.The metabolism of azimsulfuron in rice within 24 hours involved mostly O-demethylation of pyrimidine ring. The metabolite formed by 0-demethylation, metabolite 1, was herbicidally much less active on rice and weeds tested. The results obtained suggest that the selectivity of azimsulfuron between rice and C. serotinus mainly results from the rapid 0-demethylation in rice.

The microbial degradation of azimsulfuron and its effect on the soil bacterial community

“…Azimsulfuron, the active component of the commercial herbicide Gulliver® (Du Pont de Nemours, Cologno Monzese, Milan, Italy), is a postemergence sulfonylurea widely used in the weed control of rice fields. It is effective in controlling perennial weeds at very low application rates (6–25 g of active ingredient per hectare), whereas higher concentrations are needed to control annual weeds (Shirakura et al. 1995).…”

Effects of herbicide application on carbon dioxide, dissolved oxygen, pH, and RpH in paddy-field ponded water

“…The following is the mechanism of herbicidal action for each herbicide: ACN, inhibition of porphyrin biosynthesis (Koura et al 1994); Daimuron, inhibition of seminal root elongation (Ogasawara et al 1991); Cafenstrole, inhibition of elongation at the growing point (Kanzaki et al 2001); Azimsulfuron, inhibition of acetolactate synthase (ALS), which is involved in biosynthesis of branched-chain amino acids (Shirakura et al 1995); Cyhalofop-butyl, inhibition of fatty acid synthesis by activity inhibition of acetyl-CoA carboxylase (ACCase) (Ito et al 1998); Bensulfuron-methyl: inhibition of ALS, which is involved in biosynthesis of branched-chain amino acids (Yuyama et al 1987).…”

Identification, Charecterization and Quantification of Process Related Impurities in Azimsulfuron Technical

“…One of this class of sulfonylurea herbicides, azimsulfuron or 1-(4,6-dimethoxypyrimidin-2-yl)-3-[1-methyl-4(2-methyl-2H-tetrazol-5-yl)pyrazol-5-yl sulfonyl] urea, developed by DuPont is a low toxic, broad-specturm, highly selective sulfonylurea herbicide and has been found to be particularly useful as post emergent herbicide for weed control in rice-paddies and suppression of barnyard grass in rice. It is effective in controlling perennial weeds at very low application rates (6 -25 g of active ingredient per hectare) where as higher concentrations are needed to control annual weeds 6 . The mechanism of action of azimsulfuron, that it affects sensitive weeds through inhibition of the enzyme acetolactate synthase (ALS), the key enzyme involved in branched-chain amino acid biosynthesis in plants and micro-organism.…”