Breeding better beans in Tanzania

Kablanketi is a popular bean in Tanzania, known for its fast cooking time and palatable taste. It is thought to have been introduced into the country as far back as 1948. Today, bean breeders at the Tanzanian Sokoine University of Agriculture (SUA) are using Kablanketi to develop new varieties.

The following is a revised article written by Professor Susan Nchimbi Msolla (pictured), Project Leader at SUA. It originally appeared in the Kirkhouse Trust newsletter. Kirkhouse Trust  funds the “Use of marker assisted selection (MAS) to improve selection efficiency in breeding for resistance to major diseases of common bean” project, which aims to develop bean varieties with resistance to angular leaf spot, common bacterial blight and bean common mosaic virus diseases. SUA is one of PABRAs many partners and their research findings will be shared amongst the network.

Origins of a national favourite
Kablanketi is believed to have been introduced into Tanzania from Malawi as long ago as 1948. In those days, men from southern Tanzania travelled to South Africa to work in the gold mines, leaving their families behind to work the fields.

When they returned home to their wives and children, they often brought money and other goods such clothes, radios and kitchen utensils. Sometimes they also brought back seeds in the hope that they would grow well back in their homeland.

Two elderly men – Mr. Mboneshe Mwashuya (97) and Mr. Tuloline Mwalyemba (88) from Ivwanga village in Mbozi district – recall the menfolk returning with Kablanketi beans. It was collected from Salima, Malawi, through which the travellers passed through on their way back home. At the time the bean was known as Namawula, after a tree which has grey mottled bark resembling the colour of the seed. Later, colonialists changed its name to Kablanketi, a Swahili word meaning blanket because the seeds also resemble the colour of the blankets the miners carried on their return from South Africa.

When Kablanketi was introduced farmers added it to the mixture of beans they grew and sold, as is the custom in Malawi and southern parts of Tanzania. After some time, farmers realised Kablanketi was tastier and cooked quicker than other beans and so started to sell it separately.

In the mid-1980s, the popularity of the variety grew across the country and it became a popular market class bean.

Kablanketi traits 
Kablanketi is a semi climber that does not need staking. It flowers 32-35 days after planting and reaches maturity on average 74 days after planting. The most common version of Kablanketi has round seeds and is grey or purple mottled. There are other versions that differ in seed shape and colour tone. Seed shapes include round and oval and the colour of the seed can be grey, purple, brown or mottled.

Kablanketi is appreciated for its fast cooking time and good taste – both as dry bean or as a fresh bean (when the seeds have changed their colour but are not quite dry). Female food vendors in urban areas like Kablanketi because it saves fuel and reduces costs.

Breeding a better bean
Despite all these good traits, however, Kablanketi plants are susceptible to most bean diseases, so the variety is low yielding and its seed quality is sometimes poor. The average grain yield of Kablanketi is 500kg/ha.

So, the Bean Breeding Programme at Sokoine University of Agriculture started crossing it with the improved bean variety Rojo, which has good levels of disease resistance. The University cross bred with the preferred parent several times to improve Kablanketi for disease resistance, yield and plant type followed by self-pollination, and a Participatory Variety Selection exercise. The result was the release of two new varieties – Mshindi and Pesa. Mshindi has the same seed colour as Kablanketi (grey) while Pesa is red. The seed yield of Mshindi and Pesa is 1000-1500kg/ha.

Breeding out disease
Mshindi has been used as a recurrent parent in a Kirkhouse Trust funded programme aimed at developing multiple disease resistant bean varieties. The African Bean Consortium programme, specifically looks at angular leaf spot, common bacterial blight, bean common mosaic virus and bean common mosaic necrosis virus diseases. Its goal is to breed the genes for resistance to these diseases into Mshindi through molecular markers. To date, the project has generated some lines that combine the genes for resistance which are now being inbred using genotyping and phenotyping for further selection.

Expectations
The project aims to release at least two new bean varieties by the end of 2016. The varieties will carry resistance genes for each of the target diseases, while having the seed type and seed quality characteristics of Kablanketi and can be grown in both the lowland (450-1000m) and mid altitude (1001-1500m) areas of Tanzania.

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