Dynamic Seed Exchanges for the World

Exchanging seeds and other planting material, formally and informally, is nothing new. This is how societies have been adding new food, fibres and medicines to their cultures over centuries.

Every culture has incorporated new genes and foreign varieties into their own strains.

In developing countries, formal seed exchanges are either proven ancient seed systems or have been re-invented to counteract the damaging effects of the Green Revolution. Millions of farmers have seen a decrease in their standard of living due to the costly inputs that modern hybrids require. Parallel to this, in the developed nations, more and more holistic gardeners and farmers are searching for pre-hybrid varieties and setting up community seed exchanges.

As a result, a wide range of non-profit, community-based organisations, working with seeds and people have sprung up worldwide.

Large-scale, frozen seed banks primarily serve researchers and plant breeders who are either employed in or contracted to the industry – which in turn is owned for the most part by transnational corporations.

Locally managed community seed banks, on the other hand, are close to and often run by farmers. The common principle of these local seed banks is that they are more concerned with the circulation of the seeds and their free availability, than their conservation per se. They are more a clearing house than a static gene bank.

These farmer-based systems of producing and swapping seeds are valuable because they are in a state of dynamic change leading to plant improvements, accepting influxes of genes and adapting to climate change. Where farmers are also breeders, varieties are adapted to a specific natural environment with less external inputs.

Good Storage is the Key to Seed Vigour

The vegetable seeds that you have grown, selected and carefully harvested will be likely to maintain viability and vigour only until next growing season if they are kept in the open. Their life span will be multiplied many times over if well stored.

Seeds naturally deteriorate with time because they exchange gases and elements with the atmosphere. The trick is to keep those exchanges to a minimum by protecting them from heat, moisture and pests. Rules of thumb are that for every rise of 6°C temperature, a seed’s life span is shortened by half. Around one percent moisture intake has the same disastrous results. Light and fluctuations in temperature exacerbate viability loss.

High temperatures and seed moisture encourage insect activity. All species, and in some cases strains of a species, have a different life span. In a temperate climate at ambient temperatures, the lifespans of seeds of parsnip and some of the onion family are the shortest of all vegetables, less than a year. Sweetcorn is also relatively short-lived, while beans are intermediate (two to three years) and the seed of the Cucurbitaceae family (cucumbers, watermelons, pumpkins) is the longest lived in the vegetable kingdom. In the humid tropics unprotected seeds last only a few months. Even if feeling quite dry to the touch, freshly harvested seeds usually need further drying to contain only five to seven percent moisture for safe storage. For example, brassica seeds typically contain 15 percent moisture (depending on the actual relative humidity of the air). After harvest, the ripe seed should be dried in the semi shade for three to five days, then in the sun for just one day, or above a stove, keeping in mind that temperatures over 45°C might kill the seeds.

As seeds are hygroscopic, that is they reabsorb moisture easily, they should be kept in an airtight container to maintain their state of optimum dryness. The jar may be fitted with a rubber gasket to make perfect contact between lid and jar neck (inner car-type tubes work well). Half fill the jar with a desiccating agent such as dried wood ash, charcoal, oven-dried rice or peas, or even dried tightly-packed shreds of newspaper. Silica gel, calcium oxide and calcium chloride are commercial versions that that have greater capacity to absorb moisture. Cover that with a layer of cotton wool and fill as much as possible with seeds or packets of seeds, thus leaving minimum airspace. You will need to replace the moisture-absorbing material if the jar is open too often, or for long periods.

Protection from Insects

A wide range of botanicals and other oddities are used by farming communities around the world to protect grains and legume seeds from insect damage. These include cow dung ash, powdered dried chillies, turmeric powder, peanut oil, cotton, sunflower oil, (one soup spoon progressively incorporated into one kg of grains); leaves of eucalyptus, neem (Azadirachta indica) or bay laurel (at the rate of 30 per kg), and napthalene flakes. One third fine sand to two thirds seeds is said to reduce insect infestation.

Tribal people in Tamil Nadu, southern India, store legume seeds still in the pod to prevent contact between the individual seeds and to effectively reduce bacterial and fungal contamination. In the Solomon Islands and Vanuatu, beans in their pods and corn on the cob with the husk peeled back are hung on a rafter in the cookhouse. The creosote of the wood fire coats the seed and prevents insect infestation. The atmosphere is also low in humidity. Large gourds sealed with a mixture of clay and cow manure are used as containers for storing vegetable seeds in Africa and India. Bamboo joints are also used in Asia.

Your efforts to store seeds well will be rewarded with viable seeds and vigorous seedlings.


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