Interrelationship Between Photoperiodic Behavior of Grapes & Growth of Plant Tissue Cultures

The growth pattern of plant tissue cultures depends to a high degree on the level of essential nutrients and hormones in the synthetic medium. Thus, the auxin concentration has a very pronounced effect on the formation of callus or roots in many explants (3). The growth activity is, furthermore, modified by internal factors, e.g. the physiological age of the stock plants (e.g. grapes 2). The growth of plant tissue cultures, therefore, is, controlled by exogenous and endogenous factors. Investigating problems in respect to photoperiodically controlled growth of different grape varieties (1) leads to the question whether a photoperiodic pretreatment of young grape plants alters the growth activity of stem segments prepared from such pretreated plants. The experiment reported here was designed to provide this information. Similar qualitative results were obtained in experiments repeated at different times of the season.