Abstract
Runner bean (Phaseolus coccineus L.) offers a great potential as a grain legume in Africa. However, its productivity is low because no improved short-day varieties are available. The aim of this study was to evaluate advanced short-day runner bean lines for high grain yield, resistance to diseases and suitable for cultivation under tropical conditions. F6.8 recombinant inbred lines developed from crosses between local landraces and high yielding imported variety (White Emergo) were evaluated in 2013 and 2014 in a randomized complete block design with three replicates at Kabete (1860 m.a.s.l.) and Ol Joro-Orok (2300 m.a.s.l.) in Kenya. Four local runner bean landraces were used as checks. Analysis of variance showed that there were significant differences for days to flowering, response to diseases and grain yield among the evaluated lines. Improved lines flowered within 49 to 52 days in 2013 and 34 to 58 days in 2014.The improved lines flowered earlier at Kabete than Ol Joro-Orok and showed a higher degree of resistance (scores 1-3) to the major diseases rust, bean common mosaic virus (BCMV) and powdery mildew. The mean grain yield at Kabete was 4,426 kg ha-1 compared to 6,523 kg ha-1 at Ol Joro-Orok giving an average yield advantage of up to 67% compared with local short-day landraces. The results indicated that new high yielding short-day runner bean varieties with resistance to major diseases and tropical adaptation can be obtained from these lines.
Highlights
Grain legumes are rich in dietary protein compliment nutritional value of cereals
In regard to the distinction, lines KAB-RB13-326-207, KAB-RB13-37-16, KAB-RB13-379-148 and SUB-OL-RB13-269-129 were identified to flower early at both sites and years
Most evaluated lines were found to flower within the range of 30 to 60 days as documented by Purseglove, 1987.The dwarf local landraces were found to flower earlier compared to the climbers; Kin 2 and Kin 3 could be used for improvement of early flowering in runner beans
Summary
Grain legumes are rich in dietary protein compliment nutritional value of cereals. Based on (Kahuro, 1990; Suttie, 1969), the commonly grown variety in these counties is white seeded commonly referred to as ‘butter bean. This is despite the fact that runner bean has other different grain colours ranging from black, white, cream, brown or pink to purple speckled or mottled in the country. Runner bean is mainly grown both for dry grain and immature green pods as vegetable and can be of bush type or climbing. There is a need of developing improved, pure stands and certified seed for commercial production of runner beans.
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