Imazethapyr aqueous photolysis, reaction quantum yield, and hydroxyl radical rate constant.
The recent introduction of imidazolinone-tolerant rice varieties allow imazethapyr to be used in commercial rice. Little is known about imazethapyr photodegradation in the rice field. Laboratory studies were conducted to determine the direct and indirect photolysis rates for imazethapyr and to evaluate the photolysis of imazethapyr in three rice paddy waters. The reaction quantum yield (phi I) for imazethapyr was determined to be 0.023 +/- 0.002, while the hydroxyl radical rate constant (K(I)*OH) was 2.8 x 10(13) M(-1) h(-1). These results show that imazethapyr is susceptible to both direct and indirect photolysis reactions in water. The results also show that imazethapyr photolysis in paddy water will be affected by turbidity because of its impact on the availability of sunlight to drive direct and indirect photolysis reactions.
Avila
Luis A
LA
Departamento de Fitotecnia, Universidade Federal de Santa Maria (Research fellow CAPES/Brazil) 97105-900, Santa Maria, RS, Brasil. luis-avila@smail.ufsm.br
Massey
Joseph H
JH
Senseman
Scott A
SA
Armbrust
Kevin L
KL
Lancaster
Sarah R
SR
McCauley
Garry N
GN
Chandler
James M
JM
D004351:Drug Resistance; D006540:Herbicides / Q000737:chemistry*; D017665:Hydroxyl Radical / Q000737:chemistry*; D007700:Kinetics; D009539:Nicotinic Acids / Q000737:chemistry*; D012275:Oryza / Q000254:growth & development; D010782:Photolysis; D014867:Water / Q000737:chemistry*
D006540:Herbicides; D009539:Nicotinic Acids; D014867:Water; D017665:Hydroxyl Radical; C093630:imazethapyr