INFLUENCE OF PHOTOSYNTHESIS-INHIBITING HERBICIDES ON OLIVE. II. EFFECTS ON CARBOHYDRATE AND NITROGEN METABOLISM

Effects of ametryne, diuron, ioxynil, metribuzin and simazine on leaf carbohydrate and nitrogen metabolism of 14-year-old olive trees (‘Picual’) have been studied. Changes in starch, sucrose, glucose, reducing and total soluble sugar, and malic acid levels, taken as indicative parameters of carbohydrate metabolism, and in non protein and protein nitrogen levels, taken as indicative parameters of nitrogen metabolism, were weekly monitored in leaf samples over the following 35 days after herbicide treatment. A general decrease in sucrose and total and reducing sugar contents, and increase in protein and non protein nitrogen contents were observed in all treatments. Metribuzin and ametryne produced a characteristic pattern in starch evolution, with a transient accumulation followed by a sharp decline in concentration, and remarkable late decreases in glucose and malic acid contents whereas ioxynil-treated samples showed a remarkable late increase in malic acid content. In all other cases, levels of the above parameters were either similar to or lower than those in untreated controls.