Fate of a Herbicide ¹⁴<i>C</i>-Alloxydim-sodium in Sugar Beet

Degradation of Cyclohexanedione Oxime Herbicides

“…However, some radioactivity was found as conjugates of aglycone components, which indicated that biotic transformation also occurs in the plant, reaching 5% of the total degradation of alloxydim. Similar results were obtained for alloxydim when it was sprayed on several crops such as sugar beet or wild oat [38,51]. In unsterilized soil, the half-life of alloxydim was 5 to 6 days under dark incubation [52].…”

“…It was observed that alloxydim was easily degraded on the leaf surface with half-life over 1-2 days [50] whereas the herbicide was detected even after 28 days in the plant. Therefore, Hashimoto et al [50], like other authors [38,51], considered that the easy dissipation of the radiolabeled alloxydim from leaf surfaces was probably the result of photochemical reactions.…”

“…These authors also noted the thermal degradation of this herbicide at 120º C, but they did not clarify whether such degradation is related to radiation exposure [29]. Regarding the thermal degradation of CHD herbicides, Soeda et al [38] also evaluated the transformation of alloxydim when it was heated to 30, 40 and 50 ºC in a dark incubator. The thermal transformation of alloxydim was observed and 6.2% of alloxydim was degraded after 20 days of incubation at the highest temperature tested.…”

“…In order to simulate photolysis on soil surfaces, Soeda et al [38] irradiated with UV light a methanol solution of was photolyzed 33% (254 nm) and 9% (365 nm) after 20 minutes of irradiation. Ono et al [52] also concluded that photolysis of alloxydim occurred when a soil spiked with an aqueous solution of this herbicide was exposed to sunlight.…”

“…In this sense, Ono et al [52] identified the amine of alloxydim by thin-layer chromatography and mass spectrometry when the photodegradation of this herbicide was studied in sterilized soil. Alloxydim was also readily degraded in sugar beet [38] and soybean [50] and the main transformation product was identified as the amine compound. After 10 days of treatment with alloxydim, Soeda et al [38] detected the corresponding amine as the main transformation product in sugar beet extracts.…”