Browsing by Author "Kimani, P.M."
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Item Biofortification of Common Bean (Phaseolus Vulgaris L.) with Iron and Zinc: Achievements and Challenges(John Wiley & Sons Ltd., 2022-06-30) Huertas, R.; Karpinska, B.; Ngala, S.; Mkandawire, B.; Maling, J.; Wajenkeche, E.; Kimani, P.M.; Boesch, C.; Stewart, D.; Hancock, R.D.; Foyer, C.H.; The James Hutton Institute ; University of Birmingham ; University of Nairobi ; The Food, Agriculture and Natural Resources Policy Analysis Network (FANRPAN) ; Kenya Agriculture and Livestock Research Organization (KALRO) ; University of Leeds ; Heriot-Watt UniversityMicronutrient deficiencies (hidden hunger), particularly in iron (Fe) and zinc (Zn), remain one of the most serious public health challenges, affecting more than three billion people globally. A number of strategies are used to ameliorate the problem of micronutrient deficiencies and to improve the nutritional profile of food products. These include (i) dietary diversification, (ii) industrial food fortification and supplements, (iii) agronomic approaches including soil mineral fertilisation, bioinoculants and crop rotations, and (iv) biofortification through the implementation of biotechnology including gene editing and plant breeding. These efforts must consider the dietary patterns and culinary preferences of the consumer and stakeholder acceptance of new biofortified varieties. Deficiencies in Zn and Fe are often linked to the poor nutritional status of agricultural soils, resulting in low amounts and/or poor availability of these nutrients in staple food crops such as common bean. This review describes the genes and processes associated with Fe and Zn accumulation in common bean, a significant food source in Africa that plays an important role in nutritional security. We discuss the conventional plant breeding, transgenic and gene editing approaches that are being deployed to improve Fe and Zn accumulation in beans. We also consider the requirements of successful bean biofortification programmes, highlighting gaps in current knowledge, possible solutions and future perspectives.Item Screening for Drought Resistance in Small Seeded Common Beans(2012) Ombaka, J.O.; Kimani, P.M.; Naria, R.D.; Mburu, M.W.; Wambugu, J.M.Common bean (Phaseolusvulgaris L.) is sensItIve to water stress. Objective of the study was to select genotypes resistant to drought and determine traits associated with drought resistance. One hundred and eight bean genotypes from University of Nairobi Bean Research Program, the International Center for Tropical Agriculture (CIAT), The Gene Bank of Kenya (GBK) and local varieties were screened in a drought nursery from 2008 to 2010 at Kabete Field Station. The experimental design was a split plot with three replicates. The two irrigation treatments irrigated (non-stress, NS) and rainfed (drought stressed, DS) were main plots, and genotypes the sub-plots. The whole experiment received sprinkler irrigation up to flowering stage to ensure good establishment and stand uniformity. Irrigated plots (NS) received supplemental irrigation as required while the rainfed (DS) plots did not receive further irrigation until the crop was harvested. Data was collected on days to flowering, maturity, shoot biomass traits and grain yield. Yield data under stress and no stress conditions was used to calculate drought intensity index (DII). A combined analysis of variance showed that season, irrigation and genotypic effects were highly significant (P>O.O I). Severe drought (DII=O.72) reduced grain yield by 63%, while moderate drought (DII=O.3) in 2010 reduced grain yield by 40%. Thirteen genotypes from three grain types were drought resistant. Grain yield under drought stress was positively correlated with days to flowering (r=55**), days to maturity (r=0.64**), pod harvest index(r=0.57**), and negatively correlated with pod wall biomass proportion (r=-0.63**). Selection of common bean genotypes for drought stress may consider use of seed biomass, pod harvest index and reduced pod wall biomass proportion by breeders.
