Propagation of Ornamental Plants
10(4): 183-187, 2010
MICROPROPAGATION IN STATIONARY LIQUID MEDIA
John E. Preece
National Clonal Germplasm Repository, USDA-ARS, One Shields Avenue,
University of California, Davis, CA 95616-8607, Fax: +1(530)7525947,
Successful micropropagation of many species is reduced as agar concentration in the medium increases. Eliminating agar or other gelling agent completely can improve microshoot proliferation and growth. If sufficiently large established shoot masses are placed in vitro into shallow layers of liquid media so that most of the shoots remain above the media they will have sufficient aeration to support growth and proliferation. For most species, it is not necessary to provide any additional support such as rafts, filter paper, sponges, glass wool, etc. if established shoot masses are sufficiently large when transferred to stationary liquid medium. Explants can be established initially using a gelled medium and once they have grown, they can be transferred into stationary liquid media to improve micropropagation efficiency. Not all species will grow normally on stationary liquid media and water soaking or hyperhydricity will result. Hyperhydricity can be overcome by use of temporary immersion bioreactors or by using agar solidified media. If agar is used, rather than transfer to new medium at approximately monthly intervals, liquid medium can be added as a thin layer to the top of the agar and good growth will result.
Key words: agar, bioreactors, hyperhydricity, in vitro, microshoots, proliferation, temporary immersion systems