ENZYM ACTIVITIES OF JUICES FROM POTATOES TREATED WITH CHEMICALS THAT BREAK THE REST PERIOD

When freshly-harvested potatoes are treated with chemicals such as ethylene chlorhydrin, sodium thiocyanate, and thiourea the rest period is broken, and sprouts begin to make their appearance uniformly throughout the lot, after about five to eight days. The untreated potatoes planted at the same time, however, usually do not show sprouts until several weeks later, and even then the sprouting is not uniform (4). It seemed desirable to study the enzym changes that take place in the potatoes during these few days in which the processes correlated with the breaking of dormancy are in progress, and to compare them with untreated tubers under the same conditions. This paper presents the results of a series of measurements of the enzym activities of juices obtained from potatoes which had been treated with chemicals but which had not yet sprouted. The three chemicals used for treating the potatoes were ethylene chlorhydrin (ClCH2CH20H), sodium thiocyanate (NaSCN), and thiourea (NH2CSNH2). These, although quite unlike in chemical character, produce similar results in the breaking of dormancy and therefore it seemed of special interest to compare them with regard to their effects upon enzym activity. The object of the experiment was to obtain partial or complete answers to such questions as the following: What enzyms show the greatest changes? How soon after treatment do the changes start? Do the different chemicals produce the same or different effects upon the enzyms? Is there any relation between the concentration of chemical used in treating the potato and the enzym activity of the press-juice? Is there any correlation between the sprouting response and the enzym changes? Are the chemicals acting directly upon the enzyms or do the chemicals act first upon the living matter and only indirectly upon the enzyms? Do the changes occur in the absence of the eyes or must these be present to permit a response? The enzyms mainly studied in this series of experiments were catalase,