All important constraints are not biological in origin. Socio-economic factors related to farmer adoption of new technologies, seed distribution, and market requirements may also restrict bean production. New technology development is limited by the degree of organisation, resources, and the number of trained personnel within national programs (36). Networks such as PROFRIZA and SADC have proved to be a most efficient way of introducing new technologies to the small-scale farmer. Network participants include international organisations, national research institutions, state and private universities, ministries of agriculture, and nongovernmental organisations. But the most important partners are the small holders. They share their knowledge with scientists and play an active role in research aimed at developing and evaluating new technologies (10).
The small-scale farmer's main cost and biggest problem is often the purchase of high-quality seed. Network members have supported small holders by supplying high-quality seed at low cost, by developing strategies for its production and distribution, and by providing training for technicians and farmers. Seed systems need to be tailored for specific agroecological and socio-economic environments. The small seed packet technique of distribution through a diversity of channels is simple and has impressive potential for impact. In Rwanda, calculations show that 100,000 or just fewer than 10 percentage of all farmers can be reached (29).
Photo 11: Small seed packet distribution 
Breeding for resistance to diseases and pests, and for better yields, is important. The bruchid-resistant commercial bean type will make a great difference to the small-scale farmer once he has access to it. Farmers can get better prices for their beans if they can store them until the lean months when prices are highest; and this storage would also stabilise bean prices in general by providing a more continuous supply (32). The small-scale farmer would also benefit from small technology, portable, and suitable for use in his fields. Breeding of upright plants for machine harvesting would increase efficiency of commercial production. A main constraint to expanding crops in Brazil is the lack of a bean cultivar with a suitable plant type for mechanical harvest. Uniformity of maturity is also needed (6).
The introduction of improved technology has increased small-scale farming production in many areas, thus improving family nutrition and income. For example, in the Great Lakes region of Africa, the population is increasing rapidly and farms are tiny (0.5-1.0 ha) with no land for expansion. Climbing beans were introduced here 8 years ago. Now about half a million Rwandan farmers grow climbing beans on 20 percentage of the country's bean land, increasing yields (8). Another example is that of the area around Santa Cruz, Bolivia, where small-scale farmers used to leave their farms and go out to find work during the winter months. They now plant beans, a new crop for them, thanks to newly introduced varieties. This has given them access to the Brazilian market in urban areas. They have improved income and have fewer weeds, as the land is not left fallow. Women in Bolivia choose the bean seed and they have also promoted increased consumption.
Storage problems (bruchids, and discoloration, hard-shell, and hard-to-cook defects) cause the greatest post-harvest losses in beans. These problems have management solutions such as control of relative humidity and temperature for the defects, and various disinfestation and protection controls for bruchids. Genetic solutions are also available. They are cheaper in the long run but have not been exploited.
Other means of adding value to the produce are to increase different kinds of consumption, and to commercialise the end product. Beans: can be eaten as cooked dry grain, immature beans, green pods, or popped. In Africa, the young tender leaves are also eaten (22). Not all bean-consuming areas take advantage of these different uses of beans. In Peru, large quantities of seed of a single variety of popping bean are now being multiplied, which will open potential markets for snack foods in urban areas (11). Dietary habits are changing in high-income countries, as illustrated by estimates of 12,000,000 vegetarians in the USA. Because of these changes in preference, major food companies are now developing a new array of bean-based processed foods, including microwave products (23).
All evidence points to a continuing increase in total demand for beans in Latin America and Africa, and an increasing market opening in Asia. Agricultural research can make a vital contribution to improving bean production, thus helping to narrow the growing food gap. In this effort, improvements to stress tolerances, both biotic and abiotic, are likely to be far more important than increases in yield potential (23).
Beans, often a subsistence or small-farmer crop, do not receive the research attention that cash crops, such as coffee or cotton, enjoy (33). The crop offers a low-cost alternative to beef and milk. One hectare planted to traditional bean varieties in Latin America produces 123 kg of protein compared to 3-4 kg for beef cattle on the same amount of land. Donor funds for bean research are decreasing at a time when world demand is increasing for this cheap source of protein and calories. Research by international institutions is reaching the small farmer through established networks. Funding such research helps feed the poor of the world, especially women, who are often the first to suffer when food supplies are scarce.