Browsing by Author "Owuoche, J.O"

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    Characterization of Uromyces appendiculatus isolates collected from snap bean growing areas in Kenya
    (2012-11-02) Arunga, Ester E.; Ochuodho, J.O; Kinyua, M.G; Owuoche, J.O
    Bean rust (Uromyces appendiculatus (Pers.:Pers.) Unger var. appendiculatus) is one of the most devastating and variable pathogens of common bean (Phaseolus vulgaris L.) worldwide that can cause total crop loss. Characterization of bean rust races can help in screening resistant materials during gene pyramiding. The aims of the present research were first, to characterize bean rust isolates collected from snap bean growing areas in Kenya. Secondly, to identify which of the available rust resistance genes in common bean differentials are most effective to control rust in those areas. Snap bean leaf tissues with rust pustules were collected from different farms in eight locations in central and western Kenya during the years 2010 and 2011. Forty seven single pustule isolates were obtained and inoculated on 12 bean rust differential cultivars. For consistent results, the inoculation was repeated twice. The new international classification system and the binary nomenclature grouped the 47 single pustule isolates of U. appendiculatus into 9 different races, most of this affected the Andean gene pool. Hierarchical cluster analysis grouped the races into two major clusters depending on the virulence of the races on the host differential cultivars. The most resistant genes for pyramiding in Kenya were identified as Ur-5, Ur-11 and Ur-CNC. An important output of this study was the identification of races with potential use during gene pyramiding process.
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    Diallel analysis of Snap bean (Phaseolus vulgaris l.) varieties for important traits
    (2010-08-04) Arunga, Ester E.; Owuoche, J.O; Rheenen, Henk A. Van
    The breeding programmes of many crops use diallel analyses because of the genetic information they offer to breeders. Six morphological and agronomic traits of Snap bean (Phaseolus vulgaris L.) were studied to investigate their gene action, and to estimate the general combining abilities (GCA) and specific combining abilities (SCA) of parents and crosses. Three snap bean varieties - Amy, Monel and Morlane and two dry bean varieties - GLP 20 and GLPX 92 were used as parents in a complete diallel cross. The experiment was laid out in a randomized complete block design in a greenhouse. Significant (p < 0.01) additive and dominance effects were observed for days to flowering, plant height at flowering, number of pods per plant, pod weight per plant, pod length and pod diameter. Additive gene effects were predominant for all traits apart from pod weight. Significant (p < 0.01) maternal and non-maternal reciprocal effects were detected on plant height and days to flowering. Estimates of GCA, SCA and reciprocal effects suggested that Amy, Morlane and GLP 20 were generally the best combiners for incorporation into snap bean breeding programmes. This basic information is valuable for snap bean breeding programmes.