Abstract
32P-labeled Baycid was sprayed on the three kinds of rice plant which were different in growth stage, and the behavior of the insecticide on and in rice plant was examined.
1. The hydrolysis rate of Baycid in rice plant seemed to be slower than that of methyl parathion or malathion. Baycid disappeared rapidly after the application in the three kinds of rice plant, and only about 10 per cent of chloroform extractable metabolites remained as Baycid 6 hours after the application.
2. Chloroform extractable metabolites of Baycid in rice plant which were detected throughout the experimental period, consisted mainly of PS-sulfoxide and PS-sulfone, and the appearance of the oxidation products as PO-form seemed to be a small even if existed.
3. When Baycid was sprayed on the rice plant at a few days before heading stage, the Baycid metabolites tended to be accumulated to ears and grains. The content of the metabolites detected in the rice grains 29 days after the application was about 7 p.p.m., as expressed as Baycid. The metabolites in the rice grains were concentrated in bran but not in polished rice and husk.
4. The water extractable metabolites in the rice grains 14 days after the application were separated by ion exchange chromatography, and the existence of phosphoric acid, thiophosphoric acid, O, O-dimethyl phosphoric acid, O, O-dimethyl thiophosphoric acid, O-methyl O-(3-methyl-4-methylmercaptophenyl) thiophosphoric acid and one unknown metabolite were found. It was remarkable that the proportion of monodemethylated compound of Baycid is relatively high.
