Effects of 22 herbicides on the synthesis of RNA and protein were investigated in excised tissues. The assays measured ATP and orotate incorporation into RNA, leucine incorporation into protein, and the gibberellin-controlled induction of a-amylase Statistical analysis of the average responses measured in the four assays suggested that 14 of the herbicides inhibited RNA and protein biosynthesesin vivo.The most inhibitory chemicals were 4-hydroxy-3,5-diiodobenzonitrile (ioxynil), 2-sec-butyl-4,6-dinitrophenol (dinoseb), 3',4'-dichloropropionanilide (propanil), 2,3,5-trichloro-4-pyridinol (pyriclor), and isopropylm-chlorocarbanilate (chlorpropham). The activity of an RNA polymerase isolated from corn(Zea maysL.) tissue was inhibited maximally at approximately 20% by ioxynil, dinoseb, and pyriclor. Hence, interference with RNA polymerase, which performs a pivotal role in RNA and protein biosyntheses, does not fully account for all inhibitions.

Effects of 22 herbicides on the ATP content of excised soybean [Glycine max(L.) Merr., var. Lee] hypocotyls were determined and compared with interferences reported previously on RNA and protein syntheses. Herbicides that reduced ATP levels and inhibited RNA and protein syntheses were 2-sec-butyl-4,6-dinitrophenol (dinoseb), 4-hydroxy-3,5-diiodobenzonitrile (ioxynil), 3′,4′-dichloropropionanilide (propanil), isopropylm-chlorocarbanilate (chlorpropham), 2,3,5-trichloro-4-pyridinol (pyriclor), 2-chloro-N-isopropylacetanilide (propachlor), (2,4,5-trichlorophenoxy)acetic acid (2,4,5-T), and (2,3,6-trichlorophenyl)acetic acid (fenac). No herbicide was found which reduced tissue ATP levels, but did not inhibit RNA and protein syntheses. The correlations established between tissue ATP levels and inhibition of RNA and protein syntheses suggested that interference with the production of energy, required to drive the biosynthetic reactions, could be the mechanism through which these herbicides expressed their effects.

Competition between wild buckwheat (Polygonum convolvulusL.) and flax (Linum usitatissimumL.) was studied in field experiments at various North Dakota locations and in a controlled environment chamber in relation to soil moisture, soil fertility, light, wild buckwheat density, flax seeding rate, and length of the competition period. In the field, flaxseed yield losses caused by competition were lowered by increasing the flax seeding rate and by early wild buckwheat removal. Fertilizer increased flaxseed yield losses at the high seeding rate and generally doubled wild buckwheat dry matter production. Flax dry matter was reduced by competition at the lower seeding rates. The field and controlled environment studies indicated that competition occurred mostly in the root zone. In the latter study, wild buckwheat was a better competitor than flax on a dry weight basis and the dry weights appeared to be related to nitrogen uptake. Wild buckwheat utilized water for growth more efficiently than flax.