1970 Volume 39 Issue 2 Pages 202-205
The cytokinin activity of ethanol extracts from the protocorms of Cymbidium insigne ROLFE, C. pumilum ROLFE and C. goeringii REICHB. F. was examined by tobacco callus assay. The previous works with the tissue cultures of these three species have shown that the difference in organogenesis, especially in the kinetin-requirement for shoot formation, exists between the former two and the latter.
The extract of C. insigne or C. pumilum showed, at 100 gram fresh weight equivalent per litre, approximately the same activity as that of 10μg/l kinetin. The cytokinin activity of C. goeringii was considerably lower than those of above two species. It is assumed that low cytokinin activity is responsible for difficulty in shoot formation in the aseptic culture of C. goeringgi.