Cryopreservation of Populus euphratica Oliv. Seeds and Evaluation of the Cryopreserved Seeds under Laboratory and Greenhouse Conditions

Populus euphratica Oliv. is a highly heat, saline and cold tolerant native species, with wide range of ecological habitats and conditions. Seed longevity of P. euphratica is too short to be stored in traditional gene banks. For evaluating preservation of P. euphratica seeds in normal conditions (+22oC) as well as in cryogenic conditions (-196oC), three pre-cryopreservation treatments including PVS2, Desiccation and 30% Glycerol were applied before transferring the seeds into liquid nitrogen (-196oC) for 1 week, 1 month and 1 year. To evaluate the effects of the pre-treatments on seed germination and establishment, a part of the seeds were treated with PVS2, Desiccation and 30%Glycerol and incubated at +22oC, instead of liquid nitrogen (-196oC). The 30%Glycerol and PVS2 pre-treatments dramatically reduced the seed germination from 90% in control seeds to 35.00 and 41.67%. Cryogenic (-196oC) condition reduced seed germination from 90% in control seeds to 26.67% and 28.33. However, Desication showed excellent protection of seeds in cryogenic conditions in seed germination and establishment in lab and greenhouse. Control seed in normal conditions stayed for few months. Germination of cryopreserved seeds for a period of one year did not show significant reduction, compared to those kept for one week or one month at -196 oC.