Abstract
The structure-activity relationships of oximes and related compounds as seed safeners for grain sorghum (Sorghum bicolor (L.) Moench) have been investigated employing metolachlor (2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide) as the herbicide. Fresh weight measurements performed over a wide range of rates of seed treatments indicated that twenty-seven oximes and two nonoxime compounds showed promise for preventing the phytotoxicity of metolachlor to grain sorghum. However, the degree of protection varied among the compounds. Studies in structure-activity relationships suggested that chemicals containing either an oxime or a pyridyl group provided protection to grain sorghum against metolachlor. Chemicals containing an oxime moiety with at least one pyridyl group attached to the carbon atom or chemicals with multiple oxime groups in their molecular structures were highly effective as seed safeners. Also, an aryl group attached to the oxygen atom in the molecular structure of a pyridine aldoxime compound was essential for optimum activity. At rates as low as 0.25 g/kg of seed, flurazole (2-chloro-4-(trifluoromethyl)-5-thiazolecarboxylic acid, (phenylmethyl ester)) was more effective than pyridine-2-aldoxime O-benzyl ether, pyridine-2-aldoxime O-phenethyl ether, cyometrinil ((alpha)-((cyanomethoxy)imino)benzene acetonitrile) or CGA-92194 ((alpha)-(((1,3-dioxolan-2-yl)methoxy)imino)benzene acetonitrile) as a seed safener for grain sorghum to metolachlor. Grain sorghum seeds treated with pyridine-2-aldoxime O-benzyl ether at a rate of 0.75 g/kg of seed were stored 30 days without a loss of safening activity against metolachlor. Protection to grain sorghum against alachlor (2-chloro-2',6'-diethyl-N-(methoxymethyl) acetanilide), bensulide (O,O-diisopropyl phosphorodithioate-S-ester with N-(2-mercaptoethyl)benzenesulfonamide) or EPTC (S-ethyl dipropylthiocarbamate) was also observable. In addition, some protection was shown for wheat (Triticum aestivum L.) or rice (Oryza sativa L.) against metolachlor, alachlor and bensulide, but not against EPTC.
Chang, Tsern-Sh (1983). Structure-activity relationships of oximes and related compounds as seed safeners. Texas A&M University. Texas A&M University. Libraries. Available electronically from
https : / /hdl .handle .net /1969 .1 /DISSERTATIONS -589768.