Concentration of Free Radicals in the Root System of Zea mays

Abstract

Summary The ESR absorption in seeds and in seminal adventive and primary roots of 1–10 days old maize plants cultivated in distilled water in a thermostat at + 25 °C and of 14 days old plants cultivated in nutrient media was measured and the concentration of free radicals determined. The mineral content in the seeds and primary seminal roots was analysed parallel to the measurement of the ESR absorption. It was found that non-irradiated maize seeds show no ESR absorption signals: these become evident only after irradiation with gamma rays. Strong and regular ESR signals were obtained from freshly prepared root samples. After one and two years of storage, noticeable changes in the concentration of free radicals were detected in the course of repeated measurements on the samples from seminal adventive roots and the whole seminal root systems. In contrast, no such changes were observed in the samples from the whole plant. The reasons for the existence of free radicals in the seeds, roots and leaves of the plant and their role in the functioning of these organs are discussed.