1. Ngugi, K. and P. Aluka, 2019. Genetic and Phenotypic Diversity of Robusta Coffee (Coffea canephora L.). In: Caffeinated and Cocoa Based Beverages, Volume 8: The Science of Beverages, Grumezescu, A.M. and A.M. Holban (Eds.). Chapter 3, Woodhead Publishing, USA., ISBN: 978-0-12-815864-7, pp: 89-130.
2. Malith, D.M, K. Ngugi, F. Olubayo, E. Manyasa, J. Muthomi, F. Nzuve and N. Ochanda, 2019. Combining ability for earliness and yield among South Sudanese F₁ sorghum genotypes. ResearchJournali's J. Agric., 6: 1-13.
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3. Musungayi, E.M., K. Ngugi, J.W. Muthomi, V.W. Were, F.M. Olubayo and F.M. Nzuve, 2018. Evaluation of resistance of cassava half-sib progenies to cassava mosaic disease and their agronomic performances in Western Kenya. J. Agric. Sci., 10: 78-91.
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4. Mbusa, H.K., K. Ngugi, F.M. Olubayo, B.M. Kivuva, J.W. Muthomi and F.M. Nzuve, 2018. The inheritance of yield components and beta carotene content in sweet potato. J. Agric. Sci., 10: 71-81.
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5. Mbusa, H., K. Ngugi, F. Olubayo, B. Kivuva, J. Muthomi and F. Nzuve, 2018. Agronomic performance of Kenyan orange fleshed sweet potato varieties. J. Plant Stud., 7: 11-19.
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6. Yohannes, T., K. Ngugi, E. Ariga, M. Ahonsi, N. Yao and T. Abraha, 2017. A diagnostic appraisal of sorghum farming in Striga endemic areas of Eritrea. J. Agric. Sci., 9: 133-141.
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7. Ngugi, K. and P. Aluka, 2017. Harnessing Genetic, Biochemical and Quality Diversity in Coffee: Genetic, Biochemical and Green Bean Quality Diversity in Landraces of Robusta Coffee (Coffea canephora, Pierre). Lambert Academic Publishing, Germany, ISBN: 978-3-330-02412-0, Pages: 120.
8. Yohannes, T., K. Ngugi, E. Ariga, T. Abraha, N. Yao, P. Asami and M. Ahonsi, 2016. Genotypic variation for low Striga germination stimulation in sorghum “Sorghum bicolor (L.) Moench” landraces from Eritrea. Am. J. Plant Sci., 7: 2470-2482.
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9. Ngugi, K., P. Aluka, F. Bakomeza, B. Neumbe, R. Kyamuhangire, H. Ngabirano and K. Ngugi, 2016. Sensory and organoleptic cup attributes of Robusta coffee (Coffea canephora Pierre ex A. Froehner). J. Agric. Stud., 4: 101-116.
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10. Ngugi, K., P. Aluka and D. Maina, 2016. Variation of mineral micronutrient elements in robusta coffee (Coffea canephora Pierre ex A. Froehner) as measured by energy dispersive X-ray fluorescence. Annu. Res. Rev. Biol., 9: 1-13.
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11. Aluka, P., F. Davrieux, K. Ngugi, R. Omaria and F. Gerard et al., 2016. The diversity of green bean biochemical compounds in Robusta coffee (Coffea canephora Pierre ex A. Froehner) as evaluated by near infrared spectroscopy. J. Exp. Agric. Int., 12: 1-13.
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12. Ngugi, K., A.J. Ngugi, S. Osama and C. Mugoya, 2015. Combating Striga weed in sorghum by transferring resistance quantitative trait loci through molecular marker assisted introgression. J. Plant Breed. Genet., 3: 67-76.
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13. Magomere, T.O., S.D. Obukosia, S.I. Shibairo, E.K. Ngugi and E. Mutitu, 2015. Evaluation of relative competitive ability and fitness of Sorghum bicolorSorghum halepense and Sorghum bicolorSorghum sudanense F₁ hybrids. J. Biol. Sci., 15: 1-15.
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14. Magomere, T.O., E.K. Ngugi, S.I. Shibairo, E. Mutitu and S.D. Obukosia, 2015. Real time PCR mediated determination of the spontaneous occurrence of Sorghum bicolor alleles in wild sorghum populations. Afr. J. Biotechnol., 14: 551-568.
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15. Magomere, T.O., E.K. Ngugi, S.D. Obukosia, E. Mutitu and S.I. Shibairo, 2015. The population structure of wild sorghum species in agro-ecological zones of Western Kenya. Afr. J. Biotechnol., 14: 1475-1492.
16. Yohannes, T., A. Tesfamichael, D. Kiambi, R. Folkertsma and C.T. Hash et al., 2014. Marker-assisted introgression improves Striga resistance in an eritrean farmer-preferred sorghum variety. Field Crops Res., 173: 22-29.
17. Masiga, C.W., C. Mugoya, R. Ali, A. Mohamed and S. Osama et al., 2014. Enhanced Utilization of Biotechnology Research and Development Innovations in Eastern and Central Africa for Agro-Ecological Intensification. In: Challenges and Opportunities for Agricultural Intensification of the Humid Highland Systems of Sub-Saharan Africa, Vanlauwe, B., P. van Asten and G. Blomme (Eds.)., Springer, Cham, ISBN: 978-3-319-07661-4, pp: 97-104.
18. Magomere, T.O., E.K. Ngugi, S.I. Shibairo, E. Mutitu and S.D. Obukosia, 2014. Evaluation of multiplex PCR in detection of crop alleles and differential hybridization among weedy sorghum populations. J. Biol. Sci., 14: 460-471.
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19. Niyibigira, T., K. Ngugi, S. Devilliers, D. Kiambi and E. Mutitu et al., 2013. Introgressing Striga resistance from a mapped donor source into a Rwandan adapted sorghum variety. J. Renewable Agric., 1: 6-10.
20. Ngugi, K.,, W. Kimani, D. Kiambi and E.W. Mutitu, 2013. Improving drought tolerance in Sorghum bicolor L. Moench: Marker-assisted transfer of the stay-green Quantitative Trait Loci (QTL) from a characterized donor source into a local farmer variety. Int. J. Sci. Res. Knowledge, 1: 154-162.
21. Ngugi, K., R. Maswili and C. Muchira, 2013. Assessment of relationships in Kenyan sorghum land-races by simple sequence repeat molecular markers. Int. J. Scient. Res. Knowledge, 1: 276-287.
22. Ngugi, K., J.O. Collins and S. Muchira, 2013. Combining, earliness, short anthesis to silking interval and yield based selection indices under intermittent water stress to select for drought tolerant maize. Aust. J. Crop Sci., 7: 2014-2020.
23. Ngugi, K., J. Cheserek, C. Muchira and G. Chemining'wa, 2013. Anthesis to silking interval usefulness in developing drought tolerant maize. J. Renewable Agric., 1: 84-90.
24. Ngugi, K., C. Orek and A. Mwang'ombe, 2013. Morphological and physiological measurement of the stay-green trait in transgenic and non-transgenic cassava under green-house water stress conditions. J. Renewable Agric., 1: 77-83.
25. Ngugi, K., A.Nabiswa, J. Kithinji and A. Muchugi, 2013. Genetic divergence in Jatropha curcas L.: A potential bio-fuel crop in Kenya. Biofuels, 4: 313-322.
26. Kaloki, P., K. Ngugi, S. Silim and M. Mburu, 2013. Assessing genetic variability in chickpea genotypes grown under optimum and high field temperature environments in Kenya. Asian Acad. Res. J. Multi-disciplinarity, 1: 105-120.
27. Ngugi, K., A. Nabiswa and J. Kinama, 2012. Adaptation of Jatropha curcas L. in the agro-ecological environments of Kenya. Genotype Environ. Interact. Anal. Biofuels, 3: 354-359.
28. Ngugi, K., 2012. Marker Assisted Selection for Drought Tolerance and Striga Resistance: Introgressing Quantitative Trait Loci (QTL) in Farmer Preferred Varieties of Sorghum. Lambert Academic Publishing, Germany, ISBN: 978-3-8473-7213-4, Pages: 116.
29. Ngugi, K., 2012. Genetic Diversity of Kenyan Sorghum Germ-Plasm: Molecular Diversity of Kenyan Sorghum Germplasm using Simple Sequence Repeats. Lambert Academic Publishing, Germany, ISBN: 978-3-8465-4436-5, Pages: 92.
30. Ngugi, K. and C. Onyango, 2012. The analysis of the molecular diversity of Kenya Sorghum germ-plasm using mcrosatellites. J. Crop Sci. Biotech., 15: 189-194.
31. Odame, H., M. Mcharo, K. Ngugi, E. Kangai and P. Musyoka, 2011. Value Chain Analysis of the High Value Crops Sub-Sector in East and Central Africa. ASARECA, Entebbe, Uganda, ISBN: 978-92-95070-61-5.
32. Kamau, J., R. Melis, M. Laing, J. Derera, P. Shanahan and E.C.K. Ngugi, 2011. Farmers participatory selection for early bulking cassava genotypes in semi-arid Eastern Kenya. J. Plant Breed. Crop Sci., 3: 44-52.
33. Ngugi, K., W. Kimani and D. Kiambi, 2010. Introgression of the stay-green trait into a Kenyan farmer preferred sorghum variety. African Crop Sci. J., 18: 141-146.
34. Ngugi, K. and R. Mawsili, 2010. Phenotypic diversity in sorghum land races from Kenya. Afr. Crop Sci. J., 18: 165-173.
35. Kamau, J., R. Melis, M. Laing, J. Derera, P. Shanahan and E. Ngugi, 2010. Combining the yield ability and secondary traits of selected cassava genotypes in the semi-arid areas of Eastern Kenya. J. Plant Breed. Crop Sci., 2: 181-191.
36. Olweny, C.O., K. Ngugi, H. Nzioki and S.M. Githiri, 2008. Evaluation of smut inoculation techniques in sugarcane seedlings. Sugar Tech, 10: 341-345.
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37. Gichuru, E.K., M.C. Combes, E.W. Mutitu, E.C.K. Ngugi, B. Betrand and P. Lashermes, 2008. Identification of microsatellite, AFLP and SCAR markers of a locus carrying a major gene for resistance to coffee berry disease caused by Colletotrichum kahawae in Coffea arabica L. Plant Pathol., 57: 1117-1124.
38. Bull, S.E., R.W. Briddon, W.S. Sserubombwe, K. Ngugi, P.G. Markham and J. Stanley, 2007. Infectivity, pseudorecombination and mutagenesis of Kenyan cassava mosaic begomoviruses. J. General Virol., 88: 1624-1633.
39. Bull, S.E., R.W. Briddon, W.S. Sserubombwe, K. Ngugi, P.G. Markham and J. Stanley, 2006. Genetic diversity and phylogeography of cassava mosaic viruses in Kenya. J. Gen. Virol., 87: 3053-3065.
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40. Ngugi, K. and S. Mugo, 2000. The Use of Genetic Diversity in Maize Breeding in Kenya. In: Encouraging Diversity: Conservation and Development of Plant Genetic Resources, Almekinders, C. and W. de Boef (Eds.). Practical Action Publishing, London, UK., ISBN: 978-1-85339-510-9, pp: 156-160.
41. Ngugi, E.C.K., R.B. Austin, N.W. Galwey and M.A. Hall, 1996. Associations between grain yield and carbon isotope discrimination in cowpea. Eur. J. Agron., 5: 9-17.
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42. Ngugi, E.C.K., N.W. Galwey and R.B. Austin, 1993. Genotype environment interaction in carbon isotope discrimination and seed yield in cowpea (Vigna unguiculata L. Walp.). Euphytica, 73: 213-224.
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43. Austin, R.B., P.Q. Craufurd, M.A. Hall, E. Acevedo, B. da Silveira Pinheiro and E.C. Ngugi, 1990. Carbon isotope discrimination as a means of evaluating drought resistance in barley, rice and cowpeas. Bull. Soc. Bot. France. Actualités Bot., 137: 21-30.
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44. Ngugi, E.C.K., A. Shakoor and P.G.A. Omanga, 1985. Breeding for resistance against some of the major insects of cowpea and pigeon pea. Int. J. Trop. Insect Sci., 6: 365-367.
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45. Waite, B.H., A. Shakoor, W. Songa and E.C.K. Ngugi, 1984. Principal diseases of pigeon pea, chickpea and green gram in the semi-arid area of Kenya. East Africa For. J., 44: 364-375.
46. Shakoor, A., W.K. Rono and E.C.K. Ngugi, 1984. Performance of early maturing determinate chickpea varieties in dry areas of Kenya. East Africa Agric. For. J., 44: 319-325.
47. Shakoor, A., E.C.K. Ngugi, P.G.A. Omanga and M.S. Muthoka, 1984. Development of drought resistant high yielding pigeon pea lines. East Africa Agric. For J., 44: 312-317.
48. Shakoor, A., E.C.K. Ngugi, M.S. Muthoka and J.W. Kamau, 1984. Improvement of cowpea varieties for dry areas in Kenya. East Africa Agric. For. J., 44: 306-311.