Dormancy in Seeds of Charlock: III. OCCURRENCE AND MODE OF ACTION OF AN INHIBITOR ASSOCIATED WITH DORMANCY

Abstract

The dormancy of charlock seeds appears to be associated with the presence of an inhibitor which accumulates within the seed. This inhibitor diffuses into the external solution when seeds are placed in water under germination conditions or controlled experimental conditions. A small quantity of inhibitor diffuses from the seed coats but most arises from the embryo. The increase in temperature was measured by comparing the relative growth-rates of the radicles of excised charlock embryos in water and in test solutions of diffusate. The results suggest that the rate of accumulation of inhibitor in the external solution is controlled by diffusion, and that there is continuous production of inhibitor in the tissues of the embryo which have a low oxgyen tension. The critical concentration of the inhibitor which completely prevents cell elongation is rapidly attained in seeds which are dormant. The inhibitor is unlikely to be a mustard oil, such as allylisothio-cyanate.