Effect of culture period and cell density on regrowth following cryopreservation of embryogenic suspension cultures of Norway Spruce and Sitka spruce

Changes in cryotolerance, sedimented cell volume and dry weight were determined during a 21-day culture period for embryogenic suspension cultures of Norway spruce (Picea abies) and Sitka spruce (Picea sitchensis). Maximum cryotolerance was obtained for both species when the cultures were harvested in the phase of stationary growth in terms of dry weight. For P. abies, the culture period that resulted in maximum cryotolerance was similar to the culture period that resulted in maximum formation of mature embryos after 10 weeks of maturation. The initial cell density of the P. abies cultures is an important factor in affecting regrowth after cryopreservation and it was found that adjustment of the sedimented cell volume to 50% (v/v) resulted in maximum regrowth. This revised version was published online in June 2006 with corrections to the Cover Date.