Racing for Beans: How Breeding Improved Local Bean Varieties Accelerates Food and Nutritional Security in Zambia
Some of my fond teenage memories are from when my mom would ask me to go buy common beans from the open market. She would give me strict instructions to buy “Kabulangeti” beans—never any other type of bean. Years later, after I went to college and eventually became a bean breeder, the popularity of landraces such as Kabulangeti beans has not diminished. They remain so popular that they have stifled the penetration of improved bean varieties to the Zambian market.
The common bean (Phaseolus vulgaris L.) is a cheap source of protein and serves as a major food and nutritional security crop for Zambian households. Common bean production is a major component of Zambian farming systems, particularly in the Northern region where small-scale farmers—a majority of them women—grow common bean. Despite the economic importance of beans to Zambia, the national bean yield average has stagnated between 300 to 500 Kg per Ha-1, resulting in an annual deficit of 5,000MT.
Breeding Disease-Resistant Landraces Offers Improved Food Security
Two major reasons account for low common bean yields in Zambia are: 1) the widespread use of landraces (farmer varieties); and 2) poor agronomic practices by farmers. When you visit any major open market in Zambia, there are three bean genotypes, including Kabulangeti, Solwezi and Lusaka. All three landraces are popular, with the Kabulangeti landrace (identifiable by its purple color) being the most popular with over 50% market share.
I want to focus on the first challenge: the extensive use of landraces rather than improved varieties. Efforts have been made by the national Zambian legume program to introduce improved, higher yielding varieties which were developed at the International Center for Tropical Agriculture (CIAT). Unfortunately, adoption of these varieties is low because the seed types are not generally preferred by Zambian consumers (like my mom). As a breeder myself, this challenge makes me realize that we must begin to place emphasis on improving the genetics of these already accepted and widely used landraces. After all, we have not yet focused breeding interventions on these landraces.
Landrace Breeding Potential is Possible Now!
Common landraces have several biotic and abiotic stresses that constrain their yield potential. For example, the diseases "angular leaf spot” and “anthracnose” pose major constraints to productivity. However, there are immediate breeding interventions that have good prospects of improving landrace yield potential.
The genetics of resistance to the two diseases are relatively simple because there are fewer genes involved. Therefore, it is relatively easy to move the resistance genes from resistant genotypes to strengthen the popular landraces such as Kabulangeti, rather than creating new types that are not so locally popular. Additionally, because the molecular markers for resistance genes to the two major diseases are available, it is possible to efficiently and immediately improve the widely used landraces. By crossing Zambian landraces with higher yielding elite lines or varieties from breeding programs outside Zambia including CIAT, their yield potential can be improved.
We need to address specific consumer preferences in Zambia in order to release improved varieties that will be readily consumed by Zambians and thus be lucrative for farmers to adopt. Ultimately, this will enhance household food and nutritional security in Zambian households.