Breeding programs are continuously developing new maize varieties. These are often higher yielding than the older varieties or farmers’ varieties, and may have other value added traits, such as early maturity or better disease resistance.
To benefit from a new, improved variety, farmers should first obtain seeds. Seed production should be done in a manner that maintains the purity of the variety and gives good quality seeds. The experience of other countries has shown that community-based seed production systems are sustainable as long as the seeds have been produced and stored properly.
This system will lead to the emergence of small-scale seed enterprises that could form a network with private seed companies in making good quality maize seeds available to farmers across the length and breadth of the country and help in ensuring food security.
At the outset, the farmers will need good seeds of appropriate varieties and other forms of technical assistance to establish their productive capacity in the short term and to stabilize food production and rural livelihoods in the long term.
Maize is grown worldwide and is a major traditional food cereal in the tropics. In Nigeria, maize production is increasingly popular owing to its increased use as food for humans and livestock. In addition, maize has a relative yield advantage over traditional crops, such as millet and sorghum. International research centers, such as IITA, in collaboration with national research institutes, are continuously developing new maize varieties.
However, being relatively new to the African savanna, maize is plagued by a lot of production constraints. Most notable among these are Striga, streak virus infestation, and insect pests, as well as environmental problems such as drought and low soil fertility.
Poor quality seeds are another important limiting factor in maize production. Often, farmers obtain seeds from the previous season’s harvest or purchase seeds directly in the open market without regard to genetic purity.
A key activity in raising crop yields and agricultural output is increasing the availability of quality seeds and other inputs. This paper describes the recommended practices for the production of open-pollinated maize varieties (OPVs).
Reproduction in maize:
The maize plant has separate male and female flowers. The male flowers, or tassels, are located at the top of the plant, whereas the female flowers (ears and silks) develop about halfway up the stalk. The location of the tassel at the top of a relatively tall plant and its separation from the female flower promote cross-pollination among plants.
Commonly, pollen from a tassel will be blown by the wind to one or more plants nearby. Pollen is very small, and a single tassel may produce up to 25 million pollen grains. Shortly after pollen makes contact with the female silk, it germinates and grows down through the silk, eventually fertilizing the young ovule. The fertilized ovule develops into the embryonic plant within the developing seed.
The classes of maize seeds and choice of maize varieties:
There are three classes of maize seeds.
Breeder seeds:
Usually handled by the breeders, this is the first stage in the chain of seed production. The breeders impose strict control, observe isolation distances, inspect the crop, and rogue off-types regularly to maintain genetic purity. Breeder seeds are produced with wide spacing to allow maximum expression and easier roguing.
Foundation seeds:
Breeder seeds are used to produce the foundation seeds, either by researchers or by contracted seed growers. Guidelines are followed similar to those used to produce the first class of seeds. The seed crop must be inspected at least three times by NSS inspectors.
Certified seeds:
From foundation seeds certified seeds are produced in a planting pattern similar to that used for breeder and foundation seeds.
Choice of maize varieties:
Farmers embarking on maize seed production should be familiar with the available maize varieties and their characteristics. Farmers should be able to select from these varieties those that are most suitable for their location and preferred in their market.
Some of the varieties available in Nigeria are presented in Annex 1. Foundation seeds of the selected variety can be requested from either the national maize program or an international center, such as IITA. Alternatively, foundation seeds may be available through sources in the private sector.
Isolating a seed production field:
When producing seeds, a farmer wants to maintain the characteristics of a variety. Cross pollination between different maize varieties should therefore be prevented. Isolating the seed production field from other maize fields helps to achieve this. If two different varieties are grown next to each other, cross-pollination will occur between the varieties and the crop grown from such seeds will have a mixture of the characteristics of both.
Isolation of a seed crop can be done in four ways.
By space.
Maintain a distance of at least 300 m between the seed crop and any other maize field where a different variety is planted.
By time.
Sow your seed crop at least 2 weeks earlier or later than in the neighboring maize fields.
By certified seed barriers.
A barrier of genetically pure seed of the same variety may be planted within the isolation distance of the seed production field.
By natural barriers.
Seed production plots can be established on land isolated by natural or artificial forests.
Isolation by distance or time is the approach most commonly used. The goal is to have no other maize variety shedding pollen nearby when the seed production field is flowering. Wind may carry pollen further than 300 m. Thus, if there are constant strong winds in one particular direction, the distance to the next maize field should be at least 400 m.
Authors:
H.A. Ajeigbe, T. Abdoulaye, and D. Chikoye
