Seed Selection, Collection, Processing & Storage
The transference of characteristics from one season's crop to the next is carried out by seeds.
As a farmer, it is important to select, collect, process and store the best quality seed. In order to do so:
•It is important to think about seeds throughout the growing season. The whole plant must be considered- not just the individual fruit.
•Another consideration is early maturing plants: the peanuts that ripen early are the peanuts you should save seeds from rather than eating some of the season's first fruit (not an easy task).
•It is also wise to save seeds from more than one plant of the same variety in order to maintain a broader genetic base.
•The main case in which seeds are not saved for replanting is hybrids. Most off-spring from hybrids are either sterile or will not resemble the parent plant.
•It is also a good idea to keep records on the seeds saved, such as the type and number of plants which seeds were gathered from, as well as yield notations on the parent plant. Notations such as these can help one evaluate the results of seed collection.
Seed Collection
•Once you have selected the plants from which you want to gather seeds, mark them. Some farmers tie yarn or cloth on the chosen plants or mark it with a stake. It is simple important to ensure that an elite seed producing plant does not wind up being mixed in with those for consumption.
•The next concern for collecting seeds is the timing of collections. It is important not to pick seeds when they are immature, because they will be less likely to survive storage, to germinate well, or produce strong seedlings. Immature seeds are thin, light in weight, and have not accumulated enough stored nourishment to get the seed off to a good start.
Picking well ripened seeds depends on the plant but will usually fall into one of three categories (from Growing and Saving Vegetable Seeds, pp. 27-28).
1)Plants with seeds encased in fleshy fruits, such in tomatoes, eggplants, and peppers. These soft fruits should be allowed to turn fairly ripe, even a bit over-ripe, before seed is collected. The fruit should be slightly soft but they should not be so over-ripe that they begin to heat. It is also important not to allow the fruit to dry around the seed, or it may form a hard covering that will affect the storage life of the seed.
2) Seed crops, such as corn, millet, beans, sorghum, peanuts, rice and others in which the seed is the edible part of the plant. Such plants usually hold their seeds for some time after they reach maturity, giving you a chance to do your collecting pretty much when you choose, as long as the seed has become thoroughly dry. Mature plants with dry seed that tend to bend over in wind or rain may be cut and stacked in a dry place to cure and dry further before removing the seed.
3) Plants that shatter readily, scattering ripe seed as soon as it reaches maturity. Lettuce, onion, okra, and radishes not only drop their mature seeds promptly as soon as they are dry; they also tend to ripen seed gradually so that a single plant will usually have a good bit of unripe seed hanging on while mature seed is falling off.
To be sure of catching a good seed crop from such plants, you must either inspect them daily and collect ripe seed in small amounts in a paper bag as it becomes ready, or tie a ventilated paper bag over the seed head. The seed that will collect in the bag may still contain some immature specimens, but these can usually be winnowed out by pouring the seed from one container to another in a breeze.
Some plants in this group, especially those of the cabbage family, will need staking to support the stalks.
When collecting seeds directly from a plant (not from its fruit), do so on dry, sunny days, after the dew has evaporated. Accumulation of moisture on the seeds can lower seed quality. To prevent confusion, label each batch of seeds as you are collecting.
Vegetable Seeds
After harvesting seeds/fruit, the main task is to prepare the seeds for storage. For seed bearing fruits, the seeds must first be separated from the pulp.
•For tomato seeds (and sometimes cucumber and melon), the seeds are allowed to ferment for a few days to help control bacterial canker. The seedy tomato pulp from one tomato should be put into a jar with a quarter cup of water; over the next few days, the pulp and worthless seeds should rise to the top while the heavier good seeds sink to the bottom.
•For squashes/pumpkins, the seeds and pulp extracted should be separated, then the seeds should be washed thoroughly to remove all traces of vegetable matter. When spread out to dry, large seeds should be left for 5 - 6 days, smaller ones will be ready in 3 or 4 days.
•Seeds of lettuce, basil, and others which are picked dry can be sifted to remove chaff.
•For moist seeds and tree seeds: remove light weight seeds, pulp, stem and leaf debris by immersing them in water. The good seeds will sink to the bottom and most other materials (including "dud" seeds) will rise to the top.
Field Crop Seeds
•Beans, and cowpeas are removed from the dry pods. Damage to seeds can occur during extraction (especially machine) by bruising the embryonic stem or root, resulting in poor germination.
•Peanuts are harvested with the entire plant, allowed to dry for 7-10 days before being removed. They are left in the shells for several months, often until farmers begin field preparations.
•Corn, millet, rice and sorghum are harvested on the cob, candle, head, and head respectively. The seeds are allowed to dry, and then stored (sometimes for several months) before being processed.
Seed Storage
•Properly managed seeds should have a low moisture content (there are some exceptions), be free from insects and other pests, and be kept at a cool, relatively constant temperature.
•Excess moisture in the seed can lower seed quality, and decrease germination. Since it is impossible to tell exact moisture content of seeds under home conditions, it is important to allow a long drying period before storage. Even seeds that are collected dry from the plant (like sesame) should be given a few days of further air drying after removal from the plant. The larger the seed -- the longer the drying period.
Drying Seeds
Seeds should be dried in an airy place and turned, the process should take about a week. If drying seeds on paper, the paper will probably need to be changed several times. Drying too rapidly will cause shrinking and cracking of the seed or a hard, impervious, undesirable seed coat. In order to dry seeds:
1) Lay a mat, canvas, plastic sheet, or screen on the ground where the sun shines all day.
2) Spread seeds thinly and evenly.
3) Stir an turn the seeds 4-5 times a day for uniform drying. If possible, keep seeds (especially moist ones) shaded during intense heat (noon-2 p.m.)
4) Before it rains or gets dark, take the seeds indoors.
Prior to storage, clean seeds by hand picking, blowing, winnowing.
Storing Seeds
•Store only new, mature, healthy and well dried seeds. Keep these in dry and cool environments for longer viability.
•Seeds easily re absorb moisture. To maintain dryness place seeds in airtight containers like tin cans or glass jars with tight fitting lids, sealed plastic bags, or sealed barrels. Use some water absorbing materials like sifted dry wood ash, dry charcoal, powdered milk, toasted rice, or silica gel to further reduce ambient moisture.
•Label the seeds: variety, germination test results, date, dates of harvest and storage.
•Seeds may be protected fro insects by using either organic or chemical methods, including: physical barriers, mixing seeds with dry ash, powdered neem seeds, neem leaves, sand, plant oils, and either powdered insecticide or phostoxin gas.
Commonly Used Storage Methods
•Commercially available vegetable seeds are sold in vacuum sealed pots or sacks usually treated with a combination fungicide / insecticide. (Thirame & Malathion is the most common combination.)
•Cowpeas are particularly difficult to store. It is recommended that pods should be harvested as they begin to yellow, and allowed to dry in the sun. They may be further cured by raising the temperature to 60°C to kill insects and their eggs. This can usually be accomplished by spreading the seeds out on an insulated surface (a split rice sack laid across a 10 cm layer of dry grass is acceptable), and placing a clear sheet of plastic over the top, on a sunny day the temperature will reach the desired level (cooking the seeds should not be a problem). Most farmers store cowpeas in sealed containers with either sand or ash, though many use insecticide powder or phostoxin gas.
•Peanuts: Peanuts are either stored in the shell in semi-permeable sacks, or decorticated in sealed containers with either gas or insecticide powder.
•Millet, corn, sorghum, and rice are rarely stored with any sort of chemical protection. Physical barriers are common, however. Typically, seed quality is good, and storage does not pose a problem.