Cryopreservation of dormant orthodox seeds of forest trees: mazzard cherry (Prunus avium L.)

The sensitivity of dormant seeds of mazzard cherry (Prunus avium L.) of Polish provenances to extreme desiccation and/or the ultra-low temperature of liquid nitrogen, LN (-196 degrees C), was investigated to identify the optimum seed water content (w.c.) at this temperature. Germination and seedling emergence tests in this study showed that there is no critical seed w.c. for deeply desiccated seeds (stone w.c. 1.6%), although such desiccated seeds were sensitive to the temperature of LN in the seedling emergence test. For seeds frozen in LN, the highest germinability was observed at w.c. of 9.0-16.9%, but seedling emergence was then significantly lower than in nonfrozen seeds. The 2-year of storage in LN of seeds desiccated to 7.8% w.c. did not decrease germinability after thawing, in comparison with 2-year of storage at -3 degrees C. Storage in LN showed that if seeds were stored after breaking of their dormancy, germinability after storage was lower because of the necessity of seed desiccation to the lower level (similar to 8%) of w.c. after stratification (before storage). Secondary dormancy was induced in seeds desiccated after stratification. The results of this study demonstrate the potential for long-term cryopreservation of mazzard cherry seeds in forest gene banks.