The most important prerequisite for good crop production is the availability of good quality seeds of high yielding varieties, adapted to the growing area, and preferred by the farmers. The quality of seeds alone is known to account for an increase in productivity of at least 10–15%.
To achieve this high quality, all the factors in production that will affect viability, and genetic purity should be taken into account. The production techniques should be mastered and the environmental conditions (soil fertility and climate) known.
Cowpea and groundnut are both self-pollinated crops and seed production does not differ significantly. Agronomic practices in both crop and seed production are similar to those used for producing food grain. The difference lies in the standard of the output.
Good quality seeds should meet the following characteristics:
- Genetic purity and uniformity conform to the standards of the particular cultivar.
- Seeds are disease-free, viable, and free from admixtures of seeds of other crops and weeds, and inert material.
- Seeds are uniform in size, shape, and colour.
To be successful, seed producers must understand seed quality, know how it is achieved and maintained, and how they can process the seeds from harvest to their delivery to the farmers. Characteristics of seed lot quality:
Improved seeds have five related components.
Genetic superiority is inherent in the variety and has an effect on the maturity date, disease and insect resistance, and nutritional quality. Protecting genetic purity depends on accurate record keeping, the use of clean equipment, and good handling.
Crop purity means that crop is free from contaminants, including the seeds of weeds and other crops, and inert material.
Seed health refers to the absence of seed-borne diseases existing on or in groundnut or cowpea seeds.
Germination is the measure of a seed’s ability to produce a normal seedling when planted in ideal conditions (with optimal temperature and moisture plus good aeration). The seed germination test is the universal standard measure of seed quality.
Seed vigor has an important implication in the emergence rate and the final plant stand. According to their vigor, seeds can withstand stress during germination and early seedling development.
Classes of seeds:
This is the primary source for the entire system. They are usually produced by crop breeders or at least under their supervision. Breeder seeds are usually produced in a limited quantity at a time (from about 100 kg to 2–3 t/variety). This is to ensure high quality. Breeder seeds should have not less than 100% variety purity.
These are the seeds produced from the breeder seeds. An enlightened farmer can produce foundation seeds under a contract agreement with a national seed regulation body, such as the National Seed Service (NSS). Other agencies such as research institutions, ADPs, and NGOs can also be commissioned to produce foundation seeds. Foundation seeds should have 99.9% varietal purity and are used for certified seed production.
Certified seeds are produced from foundation seeds, usually by seed companies and other private seed producers certified by the NSS. Production is guaranteed by inspection and certification by an agency independent of the seed production agencies. Certified seeds are used for grain production.
Preplanting and planting decisions:
It is important to use genetically pure seeds of a given variety from a reliable source (registered seeds). Pure seeds should be obtained from the breeder or the research institution responsible for developing the variety, or from registered growers in your area.
The choice of field is an important component of good seed production. Cowpea is less demanding than groundnut and can be grown in soils of diverse types, ranging from predominantly clay to predominantly sand, and from acidic to basic. For both cowpea and groundnut, the best soil is a well-drained, sandy loam to clay loam soil with pH 6 and 7.
To manage disease, insects, and weeds, the history and crop rotation of the field should be known. It is important to select a field that was not planted in the previous year with another variety of cowpea (or groundnut, in the case of groundnut seed production). The field should be isolated from other fields of the same crop by at least 3 m for certified seed production and by 5 m for foundation seeds.
Planting equipment should be tuned-up to maximize planting efficiency with uniform plant spacing and planting depth.
Land should be prepared as early in the season as possible. The land should be cleared of old crop residues that could be burned. For cowpea that is planted later in the season, herbicide can be used before planting.
Generally, deep plowing and harrowing once or twice will provide good root growth that enables plants to get moisture from the soil. The recommendation for groundnut production in drier areas is a flat seedbed and in the forest, ridges 1 m apart and running across the slope.
For good cowpea or groundnut seed production, phosphorus and potash fertilization are required, notably in the poor soils of the Sudan savanna and Sahelian regions of West Africa. Fertilizer applied at the rate of 200 kg/ha of 0-5-15 or a combination of 30–40 kg/ha P2O5 and 25–30 kg/ha K2O is sufficient to ensure good growth of the cowpea crop.
The fertilizers should be incorporated in the soil before planting. Top dressing is not advised. For groundnut, the application of 54 kg/ha P2O5 and 25 kg/ha K2O is required to get good crop production. Fertilizer can be applied before or immediately after planting. If available, organic manure at the rate of 3 t/ha should be applied.
H.A. Ajeigbe, T. Abdoulaye, and D. Chikoye