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Selectivity of diclofop‐methyl between wheat and wild oat: growth and herbicide metabolism
Author(s) -
DONALD W. W.,
SHIMABUKURO R. H.
Publication year - 1980
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1980.tb03335.x
Subject(s) - avena fatua , avena , phytopharmacology , biology , metabolism , poaceae , weed , conjugate , chemistry , agronomy , biochemistry , mathematical analysis , mathematics
Growth of the second leaf of susceptible wild oat ( Avena fatua L.) was inhibited within 2 days after treatment with the herbicide, diclofop‐methyl, in the 1‐1/2 leaf stage. Leaf growth of resistant wheat ( Triticum aestivum L.) was unaffected by diclofop‐methyl. In wild oat. chlorosis developed 1 day after leaf growth was inhibited. Foliar absorption of diclofop‐methyl was similar between wild oat and wheat with 67 and 61% of the recovered radioactivity from [ 14 C]diclofop‐methyl being absorbed by wild oat and wheat, respectively, after 4 days. Wild oal was equally sensitive to the methyl ester and acid forms of the herbicide when the compounds were injected into the stem. Wheat was unaffected by both forms when treated similarly. Very little diclofop‐methyl and diclofop (combined total of 10 to 12% in wild oat and 5 to 7% in wheat) remained in plant tissues 2 days after leaf treatment in both susceptible and resistant plants. Therefore, the active form of the herbicide must inhibit growth of susceptible plants very rapidly and at relatively low concentrations. Diclofop‐methyl was rapidly hydrolyzed to diclofop by wild oat and wheat. Wild oat predominantly conjugated diclofop to an ester conjugate but wheat hydroxylated the 2,4‐dichlorophenyl ring and formed a phenolic conjugate. The formation of the different conjugates between wild oat and wheat was the most significant difference in metabolism between the two species. Nearly 60 and 70% of the methanol‐soluble radioactivity was present as water‐soluble conjugates in wild oat and wheat, respectively, 4 days after treatment.