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Search Results: 1 - 10 of 480 matches for " PM Kimani "
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Resistance and inheritance of common bacterial blight in yellow bean
KK Muimui, PM Kimani, JW Muthom
African Crop Science Journal , 2011,
Abstract: Common bean (Phaseolus vulgaris L.) is the most important food legume among the pulses. It is a cheap source of protein, especially in Sub-Saharan Africa. However, bean production is constrained by bacterial diseases, of which common bacterial blight (Xanthomonas axonopodis p.v. phaseoli) is prevalent in Africa. The objective of this study was to transfer resistance to common bacterial blight and determine its inheritance in yellow beans. Sources of resistance were CIAT lines, Wilk 2 and VAX 6, which were crossed with susceptible Lusaka yellow and Pembla. The parents, F1, F2 and backcross progenies were inoculated with X. axonopodis and the resulting blight severity determined. Quantitative traits, including days to flowering, number of pods, and seed yield were also determined. The F1 and backcrosses to the resistant parents were all resistant, while the F2 and backcrosses to the susceptible parents segregated in 3:1 and 1:1 ratios, respectively. Additive genetic effects were observed in quantitative traits like days to flowering, plant height, days to maturity and yield. Therefore, resistance to common bacterial blight is controlled by a single dominant gene. The resistant parents Wilk 2 and VAX 6 could be used to improve bean varieties that are susceptible to common bacterial blight.
Development of early maturing fusarium wilt resistant pigeonpea cultivars
PM Kimani, AB Nyende, S Silim
African Crop Science Journal , 1994,
Inheritance of resistance to angular leaf spot in yellow beans
JW Muthomi, KK Muimui, PM Kimani
African Crop Science Journal , 2011,
Abstract: Angular leaf spot (Phaeoisariopsis griseola (Sacc) is an important disease of common bean (Phaseolus vulgaris L.) in most parts of Africa, causing yield losses of 40-80%. This study was carried out to determine the inheritance of resistance to angular leaf spot in yellow beans. Biparental crosses were done between susceptible yellow bean genotypes and angular leaf spot resistant parents to generate F1, F2 and backcrosses. Resistance was evaluated in a screen house and field after inoculation with Phaeoisariopsis griseola. The F1 were resistant, indicating that resistance was dominant. There was no significant deviation from the expected 3:1 ratio for resistant to susceptible in the F2 population, confirming that resistance to angular leaf spot was both monogenic and dominant. The backcross to Lusaka Yellow showed a 1:1 segregation ratio, while the backcrosses to Mexico 54 were all resistant. Pembela was susceptible to angular leaf spot, while the F1 were resistant. The ratio of 3:1 represents resistant : susceptible F2 populations. All backcrosses to Mexico 54 were resistant, confirming that resistance to angular leaf spot in Mexico 54 is controlled by a single dominant gene. The results of the study showed that resistance to angular leaf spot in yellow beans is governed by a single dominant gene. This can be used to improve the local landraces by incorporating angular leaf spot resistance and high yield traits.
Reaction of selected common bean genotypes to physiological races of phaeoisariopsis griseola occuring in Kenya
IN Wagara, AW Mwangómbe, JW Kimenju, RA Buruchara, PM Kimani
African Crop Science Journal , 2011,
Abstract: The wide pathogenic variability occurring in Phaeoisariopsis griseola, the causal agent of angular leaf spot of common bean (Phaseolus vulgaris L.), dictates that new sources of resistance be continuously identified. This study was undertaken to determine the reaction of selected bean genotypes to different races of P. griseola in order to identify potential sources of resistance to angular leaf spot. Selected bean genotypes from Eastern and Central Africa Bean Research Network (ECABREN) and National Dryland Farming Research Centre (NDFRC), Katumani in Kenya were separately inoculated with forty-four races of P. griseola and evaluated for disease development under greenhouse conditions. The genotypes included small- and large-seeded types. None of the genotypes was resistant to all the races, indicating a high complexity of the pathogen population. Thirteen genotypes were resistant (disease score 1 to 3) or moderately resistant (score 4 to 6) to at least 40 of the races. Small- seeded bean genotypes ECAB 0754 and ECAB 0617 were resistant or moderately resistant to all races except Mesoamerican race 33-39 and Afro-Andean race 58-18, respectively. Genotype ECAB 0754 exhibited the highest level of resistance, with an average disease severity of 1.1%. All the resistant or moderately resistant genotypes were of the smallseeded bean types which are commercially less popular. The commonly grown large-seeded genotypes were generally susceptible. Among the bean genotypes evaluated, the small-seeded pintos and browns/yellows possessed high levels of resistance. The results of this study indicate that different bean genotypes have varying levels of resistance to angular leaf spot that can be pyramided into appropriate background to provide durable resistance.
Multiple disease resistance in snap bean genotypes in Kenya
SW Wahome, PM Kimani, JW Muthomi, RD Narla, R Buruchara
African Crop Science Journal , 2011,
Abstract: Snap bean (Phaseolus vulgaris L.) is an important export vegetable crop, produced mainly by small to medium scale farmers under various disease constraints. Disease resistant varieties can reduce reliance on fungicides, and enhance the capacities of smallholder farmers to meet the stringent European export requirements for allowable fungicide residues. This study was carried out to identify snap bean lines with multiple disease resistance to angular leaf spot (Phaeoisareopsis griseola), anthracnose (Collectotrichum lindemuthianum) and rust (Uromyces appendiculatus). Seven groups of snap bean populations of different generations, and 45 bush snap bean lines, including local checks, were evaluated for resistance to the three diseases at two locations in Kenya. The disease with the highest severity was rust, followed by angular leaf spot. Among the advanced lines, two bush lines (KSB 10 W and KSB 10 BR), and one climbing line (HAV 130) had consistent multiple resistance to angular leaf spot, anthracnose and rust at both locations. Nine lines and 674 single plants were selected from populations showing multiple disease resistance. Resistance in selected lines reduced angular leaf spot, anthracnose and rust severity by 17, 16 and 36%, respectively. The multiple disease resistant lines were not the highest yielders but had the highest number of pods per plant. Climbing snap bean lines had thick pods that could reduce pod quality.
Influence of the environment on the performance of some onion cultivars in Kenya
PM Kimani, JW Kariuki, P Peters, HD Rabinowitch
African Crop Science Journal , 1993,
Hi-Tech yet Highly Toxic: Electronic and E-Waste
JW Kimani
Journal of Language, Technology & Entrepreneurship in Africa , 2009,
Abstract: There is no gainsaying the importance of computers in today's technological development. Computers that were so rare barely 20 years ago are now almost a banality in most countries, including the developing world. However, the increase in numbers has posed a new danger of how to dispose of old computers. The practice has been to throw decrepit computers into dumpsites thus posing a fatal threat to the environment and the people. In this paper, we review the dangers posed by high tech products when they are not disposed of in the correct manner. In particular we discuss how rich nations dump toxic wastes in poor countries as a way of “assisting” them cope with economic problems. Garbage imperialism poses a real threat to world stability and health.
Infertility: Cultural Dimensions and Impact on Women in Selected Communities in Kenya
African Anthropologist , 2001,
Abstract: Infertility is a growing problem in Africa and affects the lives of many couples. As a health problem, it is largely culturally and socially constructed in such a way that even though it affects a couple it is the woman who bears the burden. This perspective has major implications for women whose status hinges on fertility performance. This paper presents the cultural construction of infertility and how it impacts on the lives of infertile women in Kenya. The presentation is based on material collected through qualitative methodologies among infertile and fertile women as well as through key informant interviews. Overall, infertility not only erodes the status of infertile women but also threatens their source of livelihood as some of their verbatim comments vividly point out. The burden of infertility is compounded by the fact that at the national programme level it is underplayed as a problem, the main focus being on fertility control. This is a situation that needs to be redressed so that those who are infertile, regardless of their numbers, receive the attention they require to experience quality life. JOURNAL OF THE PAN AFRICAN ANTHROPOLOGICAL ASSOCIATION Number 2 Volume VIII October 2001, pp. 200-216
Participatory Mapping of Terrestrial Fishery Resources in Kwale District, Kenya
P Kimani, D Obura
Western Indian Ocean Journal of Marine Science , 2004,
Abstract: A participatory mapping study was conducted in Kinondo location of Kwale district in Kenya. The area is subject to high human population and development pressure in the north, where tourism and urban development is intense, compared to lower population pressure in the south where such development is low. Our focus was to document information about these resources that have maintained fishing for many generations and to address issues of their conservation and management. The study focused on the spatial arrangement, access, ownership and use of land-based resources, mainly shrubs, grasses and trees, at four landing sites along the north-south population gradient. Participatory techniques (sketch maps, livelihood diagrams and transect walks) were applied, where trained fishers led other fishers in mapping, and the local Digo language was used for recording names. Resources were arranged in distinct vegetation zones parallel to the beach. A north-south increase in resource availability and abundance was recorded, inversely related to the higher population pressure in the north compared to the south. While much of the land on which vegetation resources are located was publicly accessible, a significant part is owned by absentee landlords, concentrated in the north. This over time results in increasingly restricted access to resources by fishermen, as shown in the more developed, northern section of the study site. Fishers also experience problems with access routes to landing sites on the beach due to encroachment on routes by beachfront development. The mapping activity revealed the potential for conflict over resource access and the need for solutions to maintain fishers' access to terrestrial resources important for fishing.
Bias in multiple genetic correlation from half-sib designs
PM Visscher
Genetics Selection Evolution , 1995, DOI: 10.1186/1297-9686-27-4-335
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