 |
SEED PRODUCTION AND SELECTION
In temperate countries, specialist seed producers concentrate on producing crops for seed, for resale to farmers through retail suppliers. These seeds are of guaranteed purity, have a high germination capacity, are free from pests and diseases and produce crops of a known high performance. In West Africa, seed production with these objectives is relatively unknown and the responsibility for ensuring that the farmer obtains good seed is often shouldered by the Extension Services of the Departments and Ministries of Agriculture and semi governmental organisations and corporations.
New varieties or cultivars of seed are produced by plant breeding. Research Stations are constantly endeavouring to improve the performance of existing
cultivars by hybridisation and selection. These new strains, when adequately tested are then usually multiplied for distribution through the Extension Services. Many new cultivars of maize, sorghum, cowpea and soya bean have been made available to
farmers in recent years, through these channels.
Many farm crops, however, are propagated from seeds kept by farmers from their own crops and the following are some of the basic precautions which should be taken when saving seed from existing crops intended for consumption or sale.
1) Seed should only be saved from plants which are healthy and free from pests and diseases.
2) Any crop from which seeds are to be kept must have shown a good yielding capacity and be well adapted to local environmental conditions.
3) It should be true to type, that is, the majority, if not all of the plants produced should have similar characteristics ; only plants which have the characters required in the next generation should be kept for seed.
4) Seeds should not be collected from crops which are likely to have crossed with similar crops grown nearby, cross pollination is likely to produce seeds which have undesirable characteristics since they will be a combination of those of both parents.
5) Seeds from F, hybrid plants should not be kept for seed since they will produce seedlings which may revert to an earlier parent used in the making of the F, hybrid, which will be inferior.
6) Seeds collected for sowing the following year should be treated with an insecticide and possibly a fungicide to reduce injury from pests and diseases during storage. They should be adequately dried in the sun and stored in cool conditions. Every effort should be made to maintain a low level of humidity.
For selecting and storing garden seeds, the same principles should be observed. Particular care should be taken to ensure that only the most vigorous and high-yielding plants are selected for seed production and the first plants to mature are not normally those which are suitable for seed.
Plants produced from early maturing crops are likely to pass on this factor to the next generation which may result in premature flowering before full stem and leaf development has taken place. In general, a closer control can be kept over the storage conditions of vegetable seeds, due to the relatively small quantities involved. Whole plants for example, may be uprooted and hung in a dry place, with sheets of paper placed below them to collect any seeds which fall when they are fully ripe and dry. After thorough drying, seeds may be stored in polythene bags or in air-tight glass jars with a material such as silica gel or calcium chloride which will absorb moisture. Many seeds have a period of dormancy through which they must pass before they are capable of germination. Germination tests, to assess the viability of seeds should therefore only be carried out after.