Studies on the Germination of Cereals

A comparative study has been made of the germination behaviour of a white-grained and a red-grained wheat variety throughout the course of maturation. Although freshly harvested wheat grains do not germinate during the early stages of ripening, the embryo will develop under germination conditions when it is completely exposed, or the epidermis of the pericarp only is removed. At the harvest-ripe stage the white grains germinate rapidly, but the emergence of the embryo is considerably delayed in the red grains. The varietal difference is due to the presence of the covering layers and becomes increasingly apparent in grains which have been prematurely harvested, between 3 and 6 weeks after anthesis, and then subjected to desiccation. This effect of the covering layers on embryo development does not appear to be related to their permeability to water or oxygen. The behaviour of the two wheat varieties is thus determined by the mechanical properties of the covering layers, and especially the pericarp. These delay germination in the red grains until there has been an increase in the water absorbing power of the imbibed embryo.