A SYNCHRONOUS MODEL OF DEVELOPMENT AND TU BERIZATION IN POTATO PLANTSCULTURED IN-VITRO WITHOUT ADDING ANY GROWTH-REGULATORS

In order to study the different steps of the growth and of the tuberiz ation process in potato, a synchronous development model was achieved in vitro from uninodal stem fragments. This result was obtained by onl y modifying the physical and nutritional factors of the environment. N o growth regulator was added to any culture medium in order to avoid a ny modification in the content level or activity of endogenous substan ces which could be further analysed as key factors in the tuberization process. The mother plant preconditioning, the origin level of the ex plant, the photo and thermoperiod as the nitrogen and sugar content of the culture medium are essential factors to take into account in orde r to optimize and synchronize the in vitro tuberization process.