Contribution to the study of the maintenance of somatic embryos of Abies nordmanniana Lk: Culture media and cryopreservation method

The maintenance of somatic embryo cultures of the Caucasian fir (Abies nordmanniana LK) was investigated through the mineral composition of culture media and the development of a simple cryopreservation method. In our culture media, a high level of NO3- (21 mM) in the absence of NH4+ appeared to favour embryo growth. The K+/Ca++ ratio seemed less significant. Moreover, the micronutrient composition of the media tested was suitable for embryo growth, provided that an optimum manganese level was maintained. The embryo cryopreservation method used involved dehydration by freezing, also known as slow cryopreservation. The technique used was a simple one, requiring no sophisticated or expensive equipment. The main criterion was to observe the crystallization point precisely by brief, rapid cooling of the embryo suspension in liquid nitrogen. The cold-treated embryos of the reference lines were able to regenerate after this treatment.