Mechanism of Action of the Herbicidal Compound LY181977
LY181977 (5-cyano-1-(1,1-dimethylethyl)-N-methyl-lH-pyrazole-4-carboxamide) is active in pre- and post-emergent applications against annual grasses in corn and cereal grains (1,2). The symptoms caused by treatment with LY181977 include growth inhibition and chlorosis, followed by necrosis and death in 14–17 days (1), similar to the symptoms caused by atrazine and diuron (3). Both atrazine and diuron bind to the thylakoid protein, D1, at the herbicide binding site, thus inhibiting photosynthetic electron transport through photosystem II (4,5,6,7). This inhibition results in increased chlorophyll fluorescence and decreased rates of the Hill reaction (8,9,10,11,12).
KeywordsChlorophyll Fluorescence Leaf Disc Oxygen Evolution Photosynthetic Electron Transport Annual Grass
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