STERILIZATION OF CORN GRAINS WITH SODIUM HYPOCHLORITE

Before carrying out a respiration study on detached roots, it was necessary to work out a method for obtaining root tissues free from microorganisms. This was essential because fungi give off considerable carbon dioxide in respiration; and the production of respiratory carbon dioxide by asterile roots may be entirely masked by the presence of these microorganisms. Following the method outlined by WnsoN (4), an aqueous extract was prepared from bleaching powder. Corn grains were treated with this solution, and allowed to germinate on sterile agar, as employed in the method of ROBBINS (2). Other grains were treated with a i per cent. organic mercury preparation, and germinated on sterile agar. Neither of these methods proved to be satisfactory. Since roots which grow from seed sterilized with the organic mercury solution frequently become infected after being detached from the seed, it was assumed that some of the microorganisms were not killed, but were merely inhibited by the disinfectant. A volatile disinfectant, sodium hypochlorite, was therefore chosen because it would either kill the fungi and bacteria on the corn grains during the period of treatment, or allow the subsequent growth and detection of the microorganisms before the roots were detached. DUGGAR and DAvIS (1) included sodium hypochlorite in their list of substances tested as seed disinfectants. They used solutions made up from solid (?) sodium hypochlorite, and obtained favorable results which, however, were not altogether uniform.