PRE-COOLING OR AN ARTIFICIAL STIMULATION OF THE MATURATION PROCESS OF WITLOOF-ROOTS (CICHORIUM INTYBUS L. VAR. FOLIOSUM) FOR EARLY FORCING.

The vegetable witloof is obtained by forcing defoliated roots. Because the grower wants to begin his production very early he is compelled to start with very young and therefore immature roots, yielding a small production of an inferior quality. The traditional method to speed up the maturation involves wilting of the harvested plants on the field before forcing. A second method, which we have developed earlier, is a cold treatment in which the roots are stored loose in a cold store. This paper deals with a special investigation aimed at increasing the effect of pre-cooling by applying modified atmospheric conditions.

The roots of three experimental series were pre-cooled, partly loose in a cold store and partly in airtight containers during 3–6–9 and 13 days at two temperatures (viz. 1°C and 4°C). Air-composition in the containers changed only by respiration. Although the production of loose stored roots is already favourably influenced by a cold treatment, pre-cooling under modified atmospheric conditions leads clearly to the best results, and then in particular with a temperature of 1°C. Within the experiments the optimal duration of the treatment was found to be 6 to 9 days.