Affiliations: National Key Laboratory of Elemento-Organic Chemistry,
Nankai University, Tianjin 300071, China | College of Life Science, Sichuan University, Chengdu
610065, China | College of Science, China Agricultural University, Key
Laboratory of Pesticide Chemistry and Application Technology of Ministry of
Agriculture, Beijing 100094, China
Abstract: Monosulfuron was developed for weed control in the field of wheat
(Triticum, aestivum L.) and millet (Panicum miliaceum L.) with the application
rate ranging from 15 to 60 g ai/hm^2. Herbicidal activity of
monosulfuron was evaluated systematically by bioassay using maize (Zea mays L.)
taproot as indicator and weed fresh weight of Acalypha australis L. and
Echinochloa phyllopogon. Maize CAU 3138 was the most tolerant cultivars to
monosulfuron with IC_{50} (concentration of 50% inhibition)
of 85 μg/kg, Yedan 13 was one of the most sensitive cultivars to
monosulfuron with IC_{50} of 6.4 μg/kg. Monosulfuron
inhibited the growth of Acalypha australis L. strongly comparing with that of
Echinochloa phyllopogon. Monosulfuron was a good acetolactate synthase (ALS)
inhibitor in vitro, the I_{50} (50% of inhibition) of
monosulfuron, chlorsulfuron, tribenuron-methyl and nicosulfuron for CAU 3138
were 32, 2, 19 and 26 nmol/L respectively, for Yedan 13 the
I_{50} were 15, 3, 17 and 65 nmol/L respectively. In vivo
ALS inhibition occurred only in higher concentration of 4 sulfonylurea
herbicide tested. Comparison study of this test indicated that the mode of
action of monosulfuron was the same as that of other sulfonylurea herbicides
such as chlorsulfuron, tribenuron-methyl and nicosulfuron, they were all
inhibitors targeted at the ALS.
