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West Africa |
DEVELOPMENT
An important success story of the International Institute of Tropical Agriculture (IITA)
which has existed in Nigeria since its inception 36 years ago,
is that of raising the status of the yam, a major food crop in West AfricaIt’s a major achievement in that IITA‘s scientists have been able to develop new genotypes of yams. The yam has been neglected by agricultural research, in spite of its food and cultural values, as well as its economic importance for hundreds of millions of people in the sub-region. But today, the yam has been elevated to the status of an elite crop, comparable in research circles to maize, wheat, rice, soybean etc.
Introduction
The yam contributes more than 200 dietary calories per capita daily for more than 150 million people in West Africa, while serving as an important source of income to the people. Global white yam production is more than 33 million metric tons. Nigeria is the world’s largest producer of yams with 27 million metric tons per annum. In the yam-producing areas of West Africa, many important cultural values are attached to the yam, especially during weddings and other social and religious ceremonies. In many yam-producing areas of Nigeria, yam is food and food is yam. People eat yams in different forms, the most important being pounded yam which the people eat more than three times a day. In spite of the tremendous importance of yams in the sub-region, the crop has generally been neglected in policy-decisions related to research, crop production and marketing. Yam production is often bedeviled by the high costs of planting and by the labour involved.
Yam sets
Yam production is daily facing the problems of genetic erosion. This often occurs in countries where war and civil unrest prevails. Here, farmers are not able to farm and preserve improved yam tubers for re-planting. Farmers are expected to set aside at least one quarter of their annual yam harvest for re-planting as the next crop (yam sets). But during emergencies, they tend to fall back on their reserves for survival. They eat everything.
In order to get good quality marketable yams, the farmers must plant good quality sets. In most cases, when the farmer intends to market part of his crop, he eats the bad ones and sells the good yams that will command good market value.
Yam sets are usually preserved in the soil after cutting into size of about 1 kg or even more. The sets are treated with wood ash and buried in the soil until the planting season, when the yam dormancy is broken and they sprout. The sets are later removed for planting in the field. While in the soil however, the sets are prone to attacks by nematodes (a kind of tiny invisible worm) and diseases inherent in the soil. Furthermore, when there is too much heat, the sets may decay, especially if the dry season is prolonged.
Because of the expense involved in ensuring good quality sets, many farmers opt for less expensive food crops such as cassava, maize, rice plantains, cowpeas, etc.
Improving the quality of yams
IITA‘s scientists have made remarkable progress in conventional yam producing. The Institute has accumulated in its germplasm, a large collection of new genotypes with better flowering qualities, which could be manipulated by crop breeders to generate new varieties. «After more than two decades of research work, we are now in good shape to combine different genes from different genotypes and then come up with completely new materials with the required acceptable attributes», says Dr. Robert Asiedu (a Ghanaian), who regards his efforts as a personal commitment to ensure the development of a crop that means so much to his region. (Ghana is a major yam producing country).
Yam minisett production technology
The yam minisett production technology was the first practical and ambitious attempt made by the IITA and the National Root Crops Research Institute (NRCRI) in order to increase yam production in Nigeria. It is a pragmatic approach to solving the problem of scarcity of planting materials, considered a major problem militating against yam production. The minisett technique has been practised by farmers in the Eastern parts of Nigeria for ages. However, the technique was not popularized until the mid-1980s when the IITA, in partnership with the NRCRI jointly worked on improving the technology, and then passed on their findings to the farmers.
The technique is the process of cutting healthy and viable small mother yams into pieces of about 50 grams, and pre-sprouting them to produce equally healthy baby yams, which take the place of the original sets for planting to obtain the bigger tubers. The technology involves the following steps:
- Selection of good mother seed yams for cutting into pieces
- Treating with wood ash or benlate, demosan or any fungicide to prevent rotting.
- Sun drying the sets in a cool dry place for about 30 minutes.
- Pre-sprouting in a basket or wooden container with the help of sawdust, which serves as the medium in which the minisetts will be pre-sprouted before transplanting in the nursery beds.
- Keeping the container in a cool dry place for about 2-3 weeks, and occasionally sprinkling it with water to encourage sprouting. This should be inspected periodically to ensure that the saw dust is neither too wet thus rotting the yams, nor too dry to prevent sprouting.
- Transplanting the planting materials when the sprouts are not too fragile to prevent breakage. The material should be planted at least two months before the planting season, to enable the sets to develop and to be ready for harvesting just before the dry season.
Advantages of yam minisett production
It encourages: The production of uniform, healthy mother seed yams; the production of more seed yams per hectare; better growing sites for commercial yam production; the rapid multiplication of yams.
It is cost-effective. With the minisett technique, the farmer can easily expand his/her holding. This applies particularly for large scale yam farmers.
With all these developments it hoped that yam culture will expand to cover the rest of the African continent particularly East and Central Africa in the near future.
- Taye Babaleye, Nigeria, August 2003 — © Reproduction authorised, with usual acknowledgment
The IITA was established on 24 July 1967 in Nigeria, as an international agricultural research and training centre for the needs of people in Sub-Saharan Africa.