After ground temperature stabilization, the repository will start accepting seeds for long-term storage. Initially it will store the IBPC’s collection of Yakutian native seeds, but in the future it is expected to grow to a national seed bank.
A 30-year experimental study carried out by the Institute of Biological Problems of the Cryolithozone (IBPC) and the Melnikov Permafrost Institute (MPI) with the long-term seed storage in permafrost under a wide range of subzero temperatures suggests that temperatures of -6° to -8°C are optimal for maintaining the viability and genetic integrity of seeds. Such low ground temperatures are only found in the northern areas, and additional cooling to reduce permafrost temperatures is required elsewhere. Ambient air is a readily available source of natural cold when its temperature in winter becomes colder than that of the ground.
Plant seeds can remain viable in a cold and dry environment for long periods. There are currently a number of long-term seed storage facilities around the world which use refrigeration equipment or natural cold with further artificial cooling to maintain desired temperatures. Their disadvantages are high power demands and the risk of collection loss due to power failure. An alternative strategy is to rely solely on the natural cold without using any machines or mechanisms.
In November 2012, the Melnikov Permafrost Institute completed the construction of a seed repository in permafrost. The facility, situated in the grounds of MPI at Yakutsk, consists of a storage room, two vertical shafts and surface buildings. The storage room, 32 m in length and 4 m in width, is located at a depth of 9.15 m. Shelving racks for seed storage containers total 90 sq. m in area. The vertical shafts are equipped with stairs and a service lift. The enclosing frozen ground has a natural temperature of -2.5°C; therefore a self-powered cooling system is used to achieve the required temperatures. The system based on natural air convection consists of two loops operating independently in summer and winter. During the summer period, temperature in the repository is controlled by an innovative method of accumulating the winter cold in near-surface frozen ground.
The project is supported by the Yakutia/Sakha Government and the Siberian Branch of the Russian Academy of Sciences.
Keywords: ex situ conservation; germination; longevity; plant genetic resources; seed storage.
More than 30 years ago, the Nordic Gene Bank established a long-term experiment on seeds stored under permafrost conditions in an abandoned mine corridor in Svalbard, as a tool to monitor storage life under these conditions. The study included seeds from 16 Nordic agricultural and horticultural crops, each represented by two or three cultivars (altogether 38 accessions). All seeds were ultra-dried to 3%-5% moisture before being sealed in glass tubes. Germination tests were performed in accordance with the International Seed Testing Association (ISTA) protocols. At the initiation of the experiment, the samples showed good germination with the median value at 92%. The overall picture remained stable over the first twenty to twenty-five years. However, the variation became larger over time and at 30 years, the median value had dropped to 80%. At the lower end, with a high drop in germination, we found rye, wheat, and English ryegrass. At the upper end, we found Kentucky bluegrass and cucumber. The lowest germination was found in samples with the highest initial seed moisture levels. Pre-storage conditions are likely to be of major importance for longevity.
The authors declare no conflict of interest. The funders had no role in the design of the study, in the collection, analysis, or interpretation of data, in the writing of the manuscript, or in the decision to publish the results.