Relationship of phytotoxic activity of cumyluron on the growth of Eleochais kurogawa Ohwi seedling to its behavior under water leakage conditions
2003
Kobayashi, K. (Tsukuba Univ., Ibaraki (Japan)) | Fuse, Y. | Shim, I.S.
Cumyluron [1-(2-chlorobenzyl)-3-(a, a-dimethylbenzyl)urea, JC-940] has potent phytotoxic effects on cyperaceous weeds, including Eleocharis kuroguwai Ohwi, a perennial weed in rice paddy fields (Tomita et al. 1991). It seems that E. kuroguwai is the most troublesome weed in paddy fields in Japan due to its high tolerance to many herbicides used in rice production (Kobayashi 1991 ; Ogasawara et al. 1991; Inamura 1994). Even E, kuroguwai tubers in deep soil may still emerge and reach the surface (Ueki et al. 1969; Ueki & Sakaguchi 1969) . Emergence depends on the elongation of the negative-geotropic rhizome, resulting in continuous growth and emergence of the weed for a long time after puddling (Ueki & Sakaguchi 1969). It has been suggested that these ecological and physiological characteristics are the main factors contributing to tolerance to the herbicide applied in the paddy fields (Inamura 1994). The phytotoxic activity of cumyluron on the growth of E. kuroguwai in paddy fields was significantly reduced when its application was delayed after the emergence of E. kuroguwai (Tomita et al. 1991), but the behavior of cumyluron in the soil has not been investigated to date. The present study was undertaken to clarify the relationship between the phytotoxic activity of cumyluron on the growth of E. kuroguwai seedlings emerging from different soil depths and its behavior in soil under water leakage conditions.
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