Wild Oat (Avena fatua) Herbicide Studies: I. Physiological Response of Wild Oat to Five Postemergence Herbicides

Abstract

Response of wild oat (Avena fatua L.) at the three-leaf stage to five postemergence herbicides, asulam (methyl sulfanilylcarbamate), barban (4-chloro-2-butynyl m-chlorocarbanilate), diclofop {2-[4-(2,4-dichlorophenoxy)phenoxy] propanoic acid}, difenzoquat (1,2-dimethyl-3,5-diphenyl-1 H-pyrazolium), and flamprop [N-benzoyl-N-(3-chloro-4-fluorophenyl)-DL-alanine] was measured and compared in nine physiological and biochemical processes (chlorophyll content, photosynthesis, photosynthate translocation, and changes in ATP, lipids, DNA, RNA, amino acids, and proteins). Content of chlorophyll a and b was reduced by the application of diclofop and difenzoquat. Photosynthesis was inhibited with all five herbicides, but photosynthate translocation from the leaves to the roots was reduced only with diclofop, difenzoquat, and flamprop. ATP production was inhibited by all herbicides except flamprop, which increased the ATP content. Incorporation of 32P into lipids was reduced by all herbicides except asulam. The incorporation of 32P into nucleic acids (DNA and RNA) was inhibited by all five herbicides. Serine and threonine, especially the latter, accumulated in large quantity with all herbicides except difenzoquat. Protein content (water-soluble,-insoluble, and total amount) was reduced by asulam, diclofop, and flamprop, but barban and difenzoquat reduced water-insoluble and total proteins only. Apparently, all herbicides examined affected more than one physiological function and biochemical process in wild oat.