Radiobiological investigations in cereals. VI. EPR measurements in single caryopses of wheat

Abstract

Characteristic properties of free radicals in the different parts of caryopses of wheat were determined at room temperature with electron paramagnetic resonance (EPR) techniques, using single caryopses or samples of 10–20 isolated embryos. The seed coatings and the embryo each contain a characteristic narrow endogenous radical signal. After gamma-irradiation of the caryopses, the peak-to-peak width of these narrow signals remains constant but a new, broad signal is induced in the endosperm at higher doses which obscures the narrow signals. At low doses the induced radical content per unit weight is about 50 per cent higher in the embryo than in the endosperm or in the seed coatings. A possible relationship between radiation induced radicals and radiation damage is discussed suggesting radical migration as a working hypothesis.