Maize

(Zea mays)

Maize or corn is a cereal crop that is grown widely throughout the world in a range of agroecological environments. More maize is produced annually than any other grain. About 50 species exist and consist of different colors, textures and grain shapes and sizes. White, yellow and red are the most common types. The white and yellow varieties are preferred by most people depending on the region.

Maize was introduced into Africa in the 1500s and has since become one of Africa's dominant food crops. Like many other regions, it is consumed as a vegetable although it is a grain crop. The grains are rich in vitamins A, C and E, carbohydrates, and essential minerals, and contain 9% protein. They are also rich in dietary fiber and calories which are a good source of energy.

Importance
Maize is the most important cereal crop in sub-Saharan Africa (SSA) and an important staple food for more than 1.2 billion people in SSA and Latin America. All parts of the crop can be used for food and non-food products. In industrialized countries, maize is largely used as livestock feed and as a raw material for industrial products. Maize accounts for 30−50% of low-income household expenditures in Eastern and Southern Africa. A heavy reliance on maize in the diet, however, can lead to malnutrition and vitamin deficiency diseases such as night blindness and kwashiorkor.

Production
Worldwide production of maize is 785 million tons, with the largest producer, the United States, producing 42%. Africa produces 6.5% and the largest African producer is Nigeria with nearly 8 million tons, followed by South Africa. Africa imports 28% of the required maize from countries outside the continent.

Most maize production in Africa is rain fed. Irregular rainfall can trigger famines during occasional droughts.

Harvesting
According to 2007 FAO estimates, 158 million hectares of maize are harvested worldwide. Africa harvests 29 million hectares, with Nigeria, the largest producer in SSA, harvesting 3%, followed by Tanzania.

Consumption
Worldwide consumption of maize is more than 116 million tons, with Africa consuming 30% and SSA 21%. However, Lesotho has the largest consumption per capita with 174 kg per year. Eastern and Southern Africa uses 85% of its production as food, while Africa as a whole uses 95%, compared to other world regions that use most of its maize as animal feed.

Ninety percent of white maize consumption is in Africa and Central America. It fetches premium prices in Southern Africa where it represents the main staple food. Yellow maize is preferred in most parts of South America and the Caribbean. It is also the preferred animal feed in many regions as it gives a yellow color to poultry, egg yolks and animal fat.

Maize is processed and prepared in various forms depending on the country. Ground maize is prepared into porridge in Eastern and Southern Africa, while maize flour is prepared into porridge in West Africa. Ground maize is also fried or baked in many countries. In all parts of Africa, green (fresh) maize is boiled or roasted on its cob and served as a snack. Popcorn is also a popular snack.

Disease incidence and constraints
Various species of stem borers rank as the most devastating maize pests in SSA. They can cause 20-40% losses during cultivation and 30-90% losses postharvest and during storage. Other pests in SSA include ear borers, armyworms, cutworms, grain moths, beetles, weevils, grain borers, rootworms, and white grubs. The parasitic Striga weed is another maize pest. In fact, weed-related yield losses ranging from 65 to 92% have been recorded in the Nigerian savanna.

Maize diseases in SSA include downy mildew, rust, leaf blight, stalk and ear rots, leaf spot, and maize streak virus (MSV).

Maize does not tolerate drought well and the grain can rot during storage in tropical climates. A lack of sunshine and nitrogen can reduce the production potential of the crop.

IITA's research and impact
IITA scientists have developed high yielding and disease-resistant varieties that are adaptable to SSA's various agroecological zones. Their research accomplishments helped to stem a serious outbreak of MSV in the 1970s.

Remarkable success was also achieved with the development of Striga-resistant varieties that suppress the weed, and other pest-resistant varieties that were released into endemic areas of Nigeria and Cameroon.

Early, intermediate, and late maturing varieties were developed with yields up to twice as much as traditional varieties. Early maturing varieties enabled maize production to expand into new areas, especially to the Sudan savannas where the short rainy season had adversely affected maize cultivation in the past.

IITA's postharvest researchers developed effective and simple machines and tools that reduce processing time and labor as well as production losses. Recently, IITA engaged in research to enhance the nutrient content of maize to combat malnutrition and diseases caused by micro-nutrient deficiency. They are also developing mycotoxin-resistant varieties in collaboration with advanced laboratories to minimize the health hazards of these toxins.

In West and Central Africa, IITA has contributed significantly to the capacity building of the national maize research systems.