frequently asked questions
Iran's Natural Resources Gene Bank supply seeds for general non-commercial research and trialling by organizations. Please note that we are unable to accept seed requests from private individuals and will not normally be able to reply to such enquiries.
All organizations making seed collections from wild plant populations that might wish to send seed for long-term conservation can send samples to Iran's Natural Resources Gene Bank.
The criteria for accepting samples are that they:
- Are of endemic or endangered species.
- Are in reasonable quantity (small collections of a few hundred seed are not acceptable).
- Are recently (last two years) harvested.
- Are well documented and include at the very least, date collected, collector(s) and accurate location (preferably with a map reference or latitude / longitude) and, ideally, sampling, ecological and other data.
As of 14 March 2015 we have in total 45000 accessions, about 1100000000 seeds from 3566 wild plant species in storage.
Storable seeds are those that can dry and not die. Drying is lethal for most organisms including mature plants. However, many seeds are tolerant of drying (desiccation-tolerant). When dry, seeds age slowly, but they will eventually die with time. Dried seeds can however also withstand freezing. When placed at sub-zero temperatures, the ageing process is further slowed down.
Species with desiccation-tolerant seeds are classified as ‘orthodox’. It is these species that we store in the Natural Resources Gene Bank. Species bearing desiccation-intolerant seeds are termed ‘recalcitrant’. Because they cannot be dried, they cannot be frozen for conventional long-term storage. This is because, on freezing, the water in the cells turns to ice, which destroys the plant cells. Dried and frozen seeds of orthodox species can live for tens or even hundreds of years. By far the majority of plant species studied is orthodox. However, the remainders are recalcitrant or intermediate between recalcitrant and orthodox in behavior. Such species cannot be stored in the Natural Resources Gene Bank. Research work is being carried out to determine why these differences exist and to explore the optimization of cryopreservation for the long-term storage of these species at Research Institute of Forests and Rangelands.
The life of a seed varies according to the species and the conditions it has been stored in. There are many stories of the germination of seeds removed from ancient Egyptian tombs. To the best of our knowledge, none of these stories is strongly supported by archaeological evidence of the antiquity of the seeds. This aside, the conditions within Egyptian pyramids are very dry and would permit seed longevity in certain species to extend to thousands of years. Nearly all of the records of extreme longevity relate to seeds with hard coats (or testas).
Seed viability has been modelled for some 70 species and it is possible to predict their longevity, given moisture content, temperature and initial germination. These models have been developed by rapidly ageing batches of seeds at a range of high moisture contents and high temperatures, and then plotting their loss of viability. Extrapolation (often a risky procedure) to viability loss under more favourable storage conditions suggests that, for instance, mung beans might live for nearly 24,000 years, and the African grass, teff (Eragrostis tef), could live for 15,000 years. Although the seed viability equation predicts survival for hundreds to thousands of years under gene-bank conditions (15% RH, -20°C), there are only a handful of credible reports of seeds actually surviving for more than 150 years.
Daws, M.I., Davies, J., Vaes, E., van Gelder, R. & Pritchard, H.W. (2007) Two-hundred-year seed survival of Leucospermum and two other woody species from the Cape Floristic region, South Africa. Seed Science Research 17: 73-79.
If recently harvested, filled, mature seeds have been placed on damp but not waterlogged compost and provided a little warmth, and they still won't germinate, the most likely causes are either inappropriate environmental conditions (particularly temperature and light) or dormancy.
The conditions required for germination, although partly genetically determined in many cases, are strongly influenced by the environment under which the seeds developed. Two seed-lots of the same species may behave in quite different ways. This said, with a little detective work and some experimentation, it is often possible to increase the likelihood of successful germination.
- The most important thing to consider is whether the seeds have a hard seed coat or some covering structure that might prevent water uptake or physically inhibit germination. If so, they may need to be scarified. Filing through the seed coat with a narrow file until the contents are just visible may be possible with larger seeds. Smaller seeds might be gently rubbed within a folded piece of fine sandpaper.
- The next thing to consider is the ecology of the species. Where does the species naturally occur in the world and at what altitude? For instance, seeds of many temperate species that are programmed to germinate in the spring often respond to a period of moist chilling. After scarification (if appropriate), the seeds can be placed on wetted tissue paper inside a reasonably airtight container and left within a refrigerator (+ 4°C) for up to three months. The moisture should be checked occasionally. Alternatively, the scarified seeds could be placed in or on moist compost and left within a cold-frame over winter. Following this treatment, the seeds can then be germinated on moist compost and in the warm as usual. Many small-seeded species need exposure to light for germination and also benefit from experiencing temperature fluctuations each day. This is an adaptation to prevent germination until the seeds are brought to the soil surface by disturbance. If none of the above work, it might be necessary to try different germination temperatures. Unfortunately, the temperature range over which seeds germinate may change as the dormancy status of the seed changes.
Taking care during the collection of seed can make a huge difference to its storability.
Collecting before the seeds are fully ripe may mean that the seed is incapable of surviving drying. Where dry seed capsules are involved, the ideal harvest time is usually when the seeds are on the point of being shed eg when a seed capsule first splits. In the case of 'wet' fruits containing seeds, the ideal harvest time is when the fruits are fully ripe, and therefore attractive to mammals and birds. Quite often, fruit ripeness is indicated by a change of colour. Seeds that are very soft or that are green are usually not ripe. Where a range of seed colours is present on the plants, some indication of which seeds to harvest can usually be worked out by looking for those seed colours that equate to seed hardness.
Unlike most seed collecting for conservation that involves random sampling, gardeners may wish to be selective of the individuals to be harvested. This will increase (though not guarantee) the chances that some of the individuals in the next generation possess similar characteristics to those selected.
Sensible precautions should be adopted when handling all seed and fruits because some are poisonous. All such material should be kept out of the reach of small children. Seeds borne within fruits need to be extracted. This can be done by scraping the seeds onto a colander or sieve followed by washing to remove pulp and juice. Sometimes after extraction, the seed is covered with a mucilaginous layer. If the seeds are spread out and left to dry, this mucilage can usually be rubbed off. Similarly, obviously empty, damaged and poorly-developed seed, plus debris, is best removed from other seed collections prior to drying and storage.
Harvested seeds need to be dried if they are to be stored. Note that this will only be true for orthodox (desiccation tolerant) species. Most garden plants grown in temperate regions will have such seed.
Drying seed shares many of the same principles as drying clothes. The one difference is that seeds (and particularly moist seeds) should never be exposed to high temperatures (and certainly not above 40°C) if they are to be kept for any length of time. Seed batches will dry most rapidly and furthest if spread out in a dry place where there is some air movement. If it is necessary to keep the seed in bags for drying, use non-glossy paper bags that allow moisture to pass out. Do not use plastic bags.
When the seeds have been dried they should be kept dry by being placed within an airtight container. Lever-lidded fruit preserving jars with rubber gaskets are usually excellent because they seal well and have a wide opening. Once dried, packaged and labelled, the seeds can be placed in a cool location. Domestic refrigerators are good though the seeds should be well separated from food and kept out of the reach of small children. When seeds are required, let the container warm up and dry off before opening. Then re-close as quickly as possible. It may be advisable to let the seeds pick up moisture from the air for several days prior to sowing, scarifying them first, if necessary.
The Natural Resources Gene Bank specialists in collecting and storing seeds from wild plant species only. Although many of these are the wild relatives of modern-day crops, we do not hold vegetable seed collections in the bank. You can find these kinds of seeds from gardening shops.
Images from web pages should not be reproduced without permission. Although Natural Resources Gene Bank has online image gallery available for download. The images in the gallery are a selection from digital photographs of seeds and fruits, arising from studies on the seed collections. These are published on this website, via our Seed Information Database. It is not particularly easy to browse the full set of images in SID (hence we have made the gallery), that is why the seeds and fruits gallery of Natural Resources Gene Bank established. Please use the images with following citation:
· If you are working for the Press
If you are an artist or photographer working for the Press, please contact Research Institute of Forests and Rangelands in the first instance.
- If you use the seed as inspiration for private artwork
The many commitments of staff at Natural Resources Gene Bank mean that we have only a limited amount of time for direct collaboration with artists and providing seeds for their private artwork projects. However, once a year at 'The Saving Species event, seeds are made available at Natural Resources Gene Bank for use by the public. In addition, we ourselves are constantly delighted and inspired by the enormous variety of form shown by seeds and fruits and we want to do as much as possible to give artists access to that diversity.
- If you are an independent artist,
If you're a fan of saving species and would like to donate your artwork to the natural Resources Gene Bank; or would like to sell your artwork in the natural Resources Gene Bank, please contact Masoumeh Ramezani Yeganeh on 021 44787280-85 (Saturday to Wednesday, 9am - 3pm).