Research firm launches new land saving bean variety

The Kenya Agricultural Research Institute (KARI) has bred two new climbing bean varieties that are higher yielding, disease tolerant and use far less farming space than the conventional bush bean varieties, in research that seems set to go to waste on poor market information.

The two varieties follow three varieties that KARI registered in 2008 as ready for adoption by farmers after approval by the Kenya Plant Health Inspectorate Services (KEPHIS). However, those seeds have yet to be commercialised by any seed producer, with seed companies steering clear of the high yield leap in beans because they face a market where they see few buyers for such an untried and unfamiliar crop.

The yields of climbing beans are enormously higher than bush beans. One climbing bean plant can produce around 100 pods in a season, compared to a bush bean’s 25 pods. Per hectare, climbing beans yield 4.2 to 5 tonnes of beans.

It has been this yield premium that has led to the widespread adoption of the climbing varieties in Rwanda, where farm land is scarce.

It has been this factor that has seen KARI chase the development of the beans in Kenya, as the rising population puts pressure on existing farmland, said Dr Robert Otsyula a Senior Bean Breeder from KARI Kakamega. This additional pressure on farming space has been most apparent in Central and Western Kenya and Kisii.

Climbing beans, first brought in from Rwanda in 1994, have been found to thrive in |Kenya’s highlands and midland regions and specifically in Embu and Meru, Kisii, Kericho and in all of western Kenya, except Busia.

When growing, the climbing beans occupy more vertical space than ground space, meaning they are well aerated, which reduces incidences of diseases. “They are not intercropped,” said Dr Otsyula, unlike bush beans which grow together with maize and other crops.

After planting, farmers harvest climbing beans when the first pods appear and continue to the last pods. 

Climbing beans mature in 86 days, but can be harvested over the following weeks too, unlike bush beans that are harvested in 86 days, after which they cease yielding. Climbing beans continue producing pods after that first harvest, although for farmers interested in a one-time harvest, they can be harvested in one go at 112 days.

The plants need to be spaced between a cluster of 3 seeds in a single hole at 30cms between plants and 75cms between rows.  One hectare requires around 20kgs of climbing bean seeds.

But the beans also add value in improving soil quality. According to a KARI research climbing beans produce 17 to 25 tons of leaves per hectare, which fix nitrogen into soil when shed. 

The climbing beans are crawlers, which means they need to be provided with something to climb. Dr Otsyula advises farmers to mount two strong poles over 3 metres high on the ends of each row and a reinforcement pole in the middle from which a strong rope or wire is tied. From that strings hang over hole with seeds. Once the beans shoot up, they are naturally able to detect strings to crawl on. “Three bean plants use one string crawler,” said Dr Otsyula.

The 3 KARI varieties approved in 2008 - Umbano, Flora and Ngwinurare - are resistant to athracnose, angular leaf spot, hallo blight and necrotic virus that affect bush beans: although farmers are advised to put in place ways to keep off mouse birds that feed on young shoots, leaves, flowers and pods.

Since KARI released the seeds,  no seed company has adopted them for commercial production. “They don’t know anything about climbing beans,” said Dr Otsyula, making them reluctant to produce them. But the seeds are available at KARI Breeding stations in Embu and Kakamega.

The Rockefeller Foundation, AGRA-Alliance and Pan-African Bean Research Alliance (PABRA) are some of the stakeholders who have funded and supported the beans project research at KARI and within East Africa.

Written by James Karuga for African Laughter

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