Influence of Simazin 50 and Dicuran on oxidative phosphorylation in the mitochondria of spring barley (Damazy) embryos

Abstract

Oxidative phosphorylation was investigated in the embryos of spring barley (Damazy) grain collected from plants sprayed in the period of shooting with Simazin 50 (2-chloro-4,6-etylamino-S-triazine) and Dicuran (N(3-chloro-4-methylphenol)N',N'dimethylurea) as well as in embryos of grains germinated in solutions of these herbicides and in 2,4-dinitrophenol. The analyses were performed on grain of varying ripeness (waxy, full post-harvest dormancy) and at various stages of germination (24, 48 h). It was found that the herbicides applied reduced succinate oxidation by the embryonal mitochondria and also depressed to the same exten the estirifi-cation of inorganic phosphate. Owing to this the P/O ratio did not show significant changes. Herbicide in germinated embryos solutions uncoupled oxidative phosphorylation. Simazin 50 (3 g/l.) and Dicuran <500 mg/l.) exhibited a weaker effect than 2,4-dinitrophenol (5X10^-4 M). They, however, greatly reduced the oxidative activity of mitochondria what may have been caused by inhibition of electron transport in the respiratory chain.