LABORATORY GROWTH STUDIES ON SARGASSUM-MUTICUM (YENDO) FENSHOLT .2. APICAL DOMINANCE

In Sargassum muticum collected during the late winter or early spring and grown in the laboratory, apical dominance was demonstrated at two levels. Primary apices inhibited the growth of secondary laterals and secondary apices controlled the development of tertiary laterals. In primary laterals the apical influence was only effective in the region near the apex and the strength of the effect decreased with increasing distance from the apex. Primary laterals did not interact, i. e. only lower order laterals were affected. When the apex was removed none of the lower order laterals became dominant over the others in the conditions described here, although this has been observed in the field. Indol-3-ylacetic acid inhibited the expansion of apical segments of primary laterals at a concentration of I ppm. © 1979, Walter de Gruyter. All rights reserved.