Micropropagation of dahlia in static liquid medium using slow-release tools of medium ingredients

Growth of dahlia shoots in vitro was ca. 4 times faster in liquid medium than on solidified medium. In liquid standard medium (3% sucrose, macroelements according to Driver–Kuniyuki Walnut medium, microelements according to Murashige–Skoog medium, 0.44 μM benzylaminopurine), the major medium ingredients were consumed for 75–80% during the first 6 weeks. Addition of extra ingredients increased growth, demonstrating that the amount of ingredients added at the start of culture was suboptimal. When the extra ingredients were given at the start of the culture, concentrations became too high and therefore inhibitory. When the ingredients were added during the subculture cycle by means of small aliquots of a concentrated solution or by means of slow-release tools, growth was strongly increased. Osmocote gave satisfactory results as a slow-release tool for inorganics. For organic ingredients (sucrose and benzylaminopurine), a novel slow-release tool was developed.

Research highlights▶ Growth of dahlia in static liquid medium is 4 times more than on solid medium. ▶ Shoot-tip necrosis does not occur in liquid medium. ▶ Extra medium ingredients applied during culture increase growth in liquid medium. ▶ Slow-release tools for medium ingredients are usable to add extra ingredients.