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Relationship of Herbicidal Activity of Soil-Applied Mefenacet to its Concentration in Soil Water and Adsorption in Soil.

1996; The Weed Science Society of Japan; Volume: 41; Issue: 2 Linguagem: Inglês

10.3719/weed.41.98

1882-4757

Katsuichiro Kobayashi, Naoki Nakamura, Ie Sung Shim, Shizuo Nagatsuka,

Plant and fungal interactions

The phytotoxic activity of mefenacet [2-(benzothiazol-2-yloxy)-N-methylacetanilide] mixed with soil on rice (Oryza sativa cv. Nipponbare) was much greater in Ryugasaki paddy soil than in Yawara paddy soil. The soil used for bioassay was centrifuged to separate it into plant available soil water and centrifuged-soil. The phytotoxic activity of mefenacet was well correlated with its concentration in soil water but not with the amount in the soil applied with the herbicide. The amount of adsorption in solid phase in soil was much more in Yawara paddy soil than in Ryugasaki paddy soil, whereas the amounts of adsorption in soil organic matter were identical. The proposed metabolites of mefenacet showed no phytotoxic activity on rice. It was suggested that the herbicidal activity of soil applied with mefenacet was induced by the herbicide's concentration in plant available soil water which was primarily determined by its adsorption in soil, mostly in soil organic matter.