Common bean (Phaseolus vulgaris L.) is the most important grain legume in human diets. It provides protein, complex carbohydrates, and valuable micronutrients for more than 300 million people in the tropics. In many areas, common bean is the second most important source of calories after maize. Over 200 million people in sub-Saharan Africa depend on the crop as a primary staple, which is cultivated largely by women. Furthermore, millions of small-scale farmers in Latin America and Africa rely on the production and sale of beans as an important source of household income.
Origin and use
The common bean appeared about 5,500 to 7,000 years ago in central Mexico where wild populations of it abound.
Common bean is grown for its green leaves, green pods, and immature and/or dry seeds. The dry seeds are the ultimate economic part of the bean plant. They are appreciated throughout the developing world because of their long storage life, good nutritional properties and ease of storage and preparation. Annual consumption can reach 66 kg per person.
Dry beans are mostly eaten whole in cooked dishes. Some manufactured products use bean flour. Dry leaves, threshed pods, and stalks are fed to animals and used as fuel for cooking, especially in Africa and Asia. In Peru and Bolivia, where high altitudes prolong cooking times and fuel costs, the ancient tradition of toasting grains in same way as corn and peanuts may be the reason why popping or ‘toasted’ beans have been developed.
The long cooking time and its associated fuel costs can cause problems for many consumers. Undesirable changes in the product during post-harvest storage can damage the grain and affect its acceptability. In addition, anti-nutrients such as protease inhibitors and lectins can block the digestion process. Factors promoting flatulence are another undesirable effect. Breeding research aims to minimize these factors.
Production
Globally, about 12 million metric tons of common beans are produced annually. Latin America is the largest producer, with some 5.5 million metric tons, with Brazil and Mexico being by far the major producers. Africa is the second most important region, producing about 2.5 million metric tons, with Uganda, Kenya, Rwanda, Burundi, Tanzania, and Congo playing major roles.
Impact of the CGIAR Centers
Impressive gains have been registered with improved common beans, developed with farmer participation through regional networks in East, Central and Southern Africa. Offering a 30–50% yield advantage and resistance to multiple diseases, the new varieties have been adopted by 5.3 million rural households over the past 15 years and currently occupy half of the region’s total bean area.
While strengthening household food and nutrition security, improved bean production also provides women (who are the main bean growers) with surplus grain to sell in local markets. The benefits of bean improvement research for Africa are estimated to have a current value of US$200 million, more than a dozen times the research costs of US$16 million.
By 1999, improved varieties of common bean were being planted on about 50% of the bean area in Latin America and the Caribbean and almost 15% in sub-Saharan Africa, boosting yields by 0.1 to 0.9 metric tons per hectare. The gross annual value of the production increases that resulted from variety adoption at that time was estimated to be around US$180 million for Latin America and the Caribbean and US$25 million for Africa, with a cumulative value since 1970 of nearly US$1.1 billion. By the end of the last century, an estimated 2 million rural households had directly benefited from improved beans.
The proportion of the total bean area planted to improved varieties containing genetic material from the International Center for Tropical Agriculture (CIAT) has doubled over the last decade, increasing to 30%. In Africa alone, these varieties benefited an additional 1 million rural households during 2010.
The spread of improved climbing beans in Rwanda is particularly striking. In recent years, thousands of farmers have switched to ‘climbers’ from the more traditional bush beans. Climbing beans are comparable to bush beans in protein content and their ability to fix nitrogen in the soil, but yield up to three times more. Some of the improved varieties also offer greater resistance to disease, while others contain more iron or zinc.
Many of the new climbing varieties originated in CIAT’s work via the Pan-Africa Bean Research Alliance, with local adaptive research being carried out by the Rwanda Agriculture Board. Rwanda now produces more beans than it can consume and supplies improved varieties to other Central and East African countries for their own breeding programs. By adapting climbers to thrive in warmer, lower altitudes, the work could reach even more farmers and help buffer the effects of climate change.
The HarvestPlus Challenge Program has taken the lead in the biofortification of common beans, and high-mineral varieties are now being released. HarvestPlus sponsored a bioefficacy study with high-iron beans in Mexico that showed a beneficial effect on iron status. High-mineral common beans have already been released in several other countries.
Sources and further information
- CIAT website. Bean program.
- CIAT. 2012. The impacts of CIAT’s collaborative research. Cali, Colombia.
- ICRISAT/CIAT/IITA. 2011. Grain Legume Value Alliance: leveraging legumes to combat poverty, hunger, malnutrition and environmental degradation. A CGIAR Research Program submitted by ICRISAT, CIAT and IITA to the CGIAR Consortium Board.
- Akibode S and Maredia M. 2011. Global and regional trends in production, trade and consumption of food legume crops. Report submitted to the CGIAR Standing Panel on Impact Assessment.
- HarvestPlus website. Iron beans.
- Jones AL. 1999. Phaseolus bean: post-harvest operations. Rome, FAO.
- Common bean photo: Orlando Toro/CIAT