The seed and tissue bank at the PAN Botanical Garden - CZRB in Powsin was established in the early 1990s. Activities undertaken in the bank are the practical fulfillment of Poland's international obligations in the field of active nature conservation ex situ. One of the goals of the Strategic Plan for Biodiversity 2011-2020, adopted at the 10th Meeting of the Conference of the Parties to the Convention on Biological Diversity (CBD COP10) (Aichi Targets), is to prevent the extinction of endangered species. The ambition is that by 2020, the extinction of known endangered species will be prevented and their conservation status, especially of the most declining species, will be improved and sustainable. "Global Strategy for Plant Conservation" for 2011-2020, in the formulated tasks, specifies that 75% of endangered plant species should be in collections of ex situ botanical gardens and seed banks, and 20% of them should be included in a program of restoration to the wild.

Low temperature storage (-20^oC) and seeds and tissues - cryopreservation - preservation in liquid nitrogen at temperatures from -160°C to -196°C.

To prepare seeds for long-term storage, a methodology developed at the Royal Botanic Gardens Kew (UK) is used, as described in "Recommendations and Protocols of the Seed Banks" (http://ensconet.maich.gr/PDF/Curation_protocol_Polish.pdf) and internal seed bank procedures.

The most important stage of the work is seed drying. This is the most critical step in preparing seeds for preservation in the bank. Lowering the original moisture level of the sample to about 6-8% is necessary due to the low temperatures at which the seeds will be deposited. This process is carried out in a special chamber, where the seeds undergo slow drying at +20°C and 20% relative humidity. Germination tests are then conducted. If the sample proves viable, it is subjected to further steps in preparation for freezing.

Seed samples, after cleaning, drying and assessing viability, are evaluated for resistance to freezing. The main threat from the freezing process is the crystallization of the water contained in the seeds. The growth of ice crystals can cause mechanical damage to the frozen material, but by reducing the water content of the seeds in advance, it is possible to freeze the seeds safely.