INFLUENCE OF PHOTOSYNTHESIS-INHIBITING HERBICIDES ON OLIVE. I. EFFECTS ON CHLOROPLAST ACTIVITY AND STRUCTURE

Effects of ametryne, diuron, ioxynil, metribuzin and simazine on chloroplast activity and structure in leaves of 14-year-old olive trees (‘Picual’) have been studied. Photochemical O₂ production and chlorophyll fluorescence emission, taken as indicative parameters of chloroplast activity, and chlorophyll a/b ratio and fatty acid composition of thylakoid lipids, taken as indicative parameters of chloroplast structure, were weekly analyzed in leaf samples during a 35-day period after treatment. The tested herbicides showed different translocation rates as well as intensity and persistence of their inhibitory effects. The above parameters varied between herbicides as follows: Translocation rate, ioxinil (I) > ametryne (A) > diuron (D) = metribuzin (M) > simazine (S); inhibitory activity, A = I = M > D > S and persistence of the inhibitory effect, M >> A > S > D > I. With respect to structural parameters a somewhat similar decrease in chlorophyll a/b ratio and increase in saturated/unsaturated fatty acid ratio was observed in all herbicide-treated samples.