Seedbank

A seed bank (also seedbank or seeds bank) stores seeds to preserve genetic diversity; hence it is a type of gene bank. There are many reasons to store seeds. One reason is to have on-hand the genes that plant breeders need to increase yield, disease resistance, drought tolerance, nutritional quality, etc. of plants used in agriculture (i.e., crops or domesticated species). Another reason is to forestall loss of genetic diversity in rare or imperiled plant species in an effort to conserve biodiversity ex situ. Many plants that were used centuries ago by humans are used less frequently now and seed banks offer a way to preserve that historical and cultural value. Collections of seeds stored at constant low temperature and moisture guard against loss of genetic resources that are otherwise maintained in situ or in field collections. These alternative 'living' collections can be damaged by natural disasters, outbreaks of disease or war. Seed banks are considered seed libraries and contain valuable information about evolved strategies to combat plant stress or produce novel products. The work of seed banks spans decades and even centuries. Most seed banks are publicly funded and seeds are usually available for research that benefits the public.

Seed banks store seeds to keep them viable. Distribution of seeds from seed banks is a form of swapping seeds

The Global Seed Vault is situated in Svalbard, midway between Norway and the Arctic.

Seeds are living creatures and keeping them viable over the long term requires adjusting storage moisture and temperature appropriately. As they mature on the mother plant, many seeds attain an innate ability to survive drying. Survival of these so-called 'orthodox' seeds can be extended by dry, low temperature storage. The level of dryness and coldness depends mostly on the longevity that is required and the investment in infrastructure that is affordable. Practical guidelines from a US scientist in the 1950s and 1960s, James Harrington, are known as 'Thumb Rules.' The 'Hundreds Rule' guides that the sum of relative humidity and temperature (in Fahrenheit) should be less than 100 for the sample to survive 5 years. Another rule is that reduction of water content by 1% or temperature by 10 degrees Fahrenheit will double the seed life span. Research from the 1990s showed that there is a limit to the beneficial effect of drying or cooling, so it must not be overdone.

Understanding the effect of water content and temperature on seed longevity, the Food and Agriculture division of the United Nations and a consultancy group called Bioversity International developed a set of standards for international seed banks to preserve seed longevity. The document advocates drying seeds to about 20% relative humidity, sealing seeds in high quality moisture-proof containers, and storing seeds at -20 degrees Celsius. These conditions are frequently referred to as 'conventional' storage protocols. Seeds from our most important species - corn, wheat, rice, soybean, pea, tomato, broccoli, melon, sunflower, etc.—can be stored in this way. However, there are many species that produce seeds that do not survive the drying or low temperature of conventional storage protocols. These species must be stored cryogenically. Seeds of citrus, coffee, avocado, cocoa, coconut, papaya, oak, walnut and willow are a few examples of species that should be preserved cryogenically.

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