Papers by Prof Kahiu Ngugi
Journal of Agricultural Science
Organoleptic and biochemical attributes in the coffee bean determine the final cup quality of cof... more Organoleptic and biochemical attributes in the coffee bean determine the final cup quality of coffee which is a critical factor in the price determination of coffee in the market. The study aimed at determining the genetic variability of the green coffee bean. The trial sites were located at Siaya and Busia counties in Kenya. Nineteen different genotypes were established and included Arabusta coffee hybrids, backcrosses of Arabica to tetraploid Robusta, Arabica coffee, Robusta coffee, and Arabusta coffee. Randomized Complete Block Design with three replications in each site was used in conducting the experiment. The coffee beans were harvested in the year 2018 and extraction and calculation of sucrose, trigonelline, caffeine, and chlorogenic acids was carried using the recommended methods. The cupping procedure involved the use of five judges in assessing the flavor, aroma, balance, overall standard, acidity, body, and aftertaste of the roasted coffee beans. The sensory evaluation u...
Backcross breeding enables breeders to transfer a desired trait from a Genetic Improvement of Ken... more Backcross breeding enables breeders to transfer a desired trait from a Genetic Improvement of Kenyan sorghum variety for drought resistance donor parent, into the favoured genetic background of a recurrent parent. This study utilised back-cross breeding to transfer stay green quantitative trait locus (QTLs) from the donor parental line E36-1 into a Kenyan farmer-preferred variety, Ochuti as the recurrent parental line. The parental lines E36-1 has 3 stay green QTLs, SBI-01, SBI-07 and SBI-10 located at various chromosomes. The transfer of these QTLs was confirmed with the help of Simple Sequence Repeats (SSRs) molecular markers. Five foreground markers that were polymorphic among the two parental genotypes were used to identify individuals of F1 generation that had stay green QTLs transferred into Ochuti. A maximum of two QTLs, namely, SBI-07 and SBI-10 were identified as having been transferred into three individual genotypes. Two other F1 genotypes had only one QTL (SBI-10) transf...
Cutting-edge Research in Agricultural Sciences Vol. 12, 2021
Climate change is hastening the genetic degradation of numerous crops in Kenya's semi-arid re... more Climate change is hastening the genetic degradation of numerous crops in Kenya's semi-arid regions, jeopardising the food security of resource-poor farmers. Using simple sequence repeat (SSR) markers, this study evaluated the genetic diversity of available Sorghum bicolor L. germplasm with the goal of discovering varieties that can be chosen to suit the food security demands of these marginal areas. 39 SSR markers were genotyped on accessions from four agro-ecological areas based on their location in the genome and the high repeat sizes they represented. The alleles were called using the Gene Mapper software (version 3.7), sizes assigned with the allelobin software and the subsequent data analyzed with the Power Marker software (version 3.25). The diversity indices and intra-population structure were calculated using the Arlequin programme (version 2.0). Rogers modified distance was used to compute genetic distances, and principal component analysis was used to cluster the acces...
Understanding the dynamics of genetic resources and improving and maintaining sorghum productivit... more Understanding the dynamics of genetic resources and improving and maintaining sorghum productivity require characterising the available Kenyan sorghum genetic diversity. The aim of this study was to determine the extent and structure of diversity in Kenyan sorghum landraces. The diversity of 148 sorghum accessions collected from Kenya's Western, Turkana, Coast, and Eastern regions was assessed using phenotypic data. The accessions were phenotyped using qualitative and quantitative morphological characters. The majority of the accessions were high yielding, as evidenced by the number of panicle branches (43), the length of the panicle (21 cm), and the grain weight (1.5 g). The majority of the sorghums were late maturing and tall, as evidenced by the number of leaves and nodes, as well as the average number of days to 50% blooming (88 days). The maturity, height, and panicle length of Turkana and coast sorghums were identical. The number of panicle branches had the highest Broad-sense heritability (0.957). Majority of the sorghums had dull green midrib (49.55%), no basal tillers (83%), had waxy bloom (39.64%) and produced prop roots (87%). Erect panicles that were loose or semi-loose predominated (69%) and peduncles that were slightly exerted predominated (83%) in the accessions. PCA demonstrated 67 percent of the total variance with only two Eigen values. The findings of phenotypic cluster analysis revealed two major groups, each of which was subdivided into four sub clusters.
Sorghum, the second most important cereal crop in Kenya is often attacked by Striga hermonthica w... more Sorghum, the second most important cereal crop in Kenya is often attacked by Striga hermonthica weed with grain yields being reduced up to 100%. In the marginal and semi-arid areas, there is urgent need to enhance the genetic resistance to Striga hermonthica in local varieties. The aim of this study was to introgress Striga resistance from a documented resistant donor line N13, into Ochuti, a susceptible farmer preferred variety through molecular marker assisted selection (MAS). Two backcross populations namely, BC 2 F 1 and BC 3 F 1 were generated by crossing N13, the donor parent to Ochuti, the recurrent parent line and the resultant backcrossed Striga resistant progenies were subjected to phenotypic selection initially. At the BC 3 F 1 stage, fore-ground selection for the Striga resistance Quantitative Trait Loci (QTLs) was conducted through Polymerase Chain Reaction (PCR) and N13 and Ochuti alleles sized through capillary electrophoresis. Eleven polymorphic markers identified at...
Australian Journal of Crop Science, 2021
Robusta coffee yields higher than Arabica coffee. However, it is limited by the inferior cup qual... more Robusta coffee yields higher than Arabica coffee. However, it is limited by the inferior cup quality. The biochemical compounds found in coffee interact and determines the final cup quality. The objective of the study was to characterize the biochemical compounds found in Arabusta coffee hybrids. Twenty coffee genotypes including the Arabusta hybrids, backcrosses, Robusta and Arabica coffee were established at KALRO-Alupe (Busia) and Siaya -ATC in the year 2015. Coffee cherry was harvested and processed in the year 2018 and the green beans were analysed for sucrose, oil, trigonelline, caffeine and chlorogenic acids using the HPLC and soxhlet method. There were significant differences amongst the genotypes for these biochemical compounds across the two different environments (Busia and Siaya counties). Robusta recorded higher levels of caffeine and chlorogenic acids while the Arabusta hybrids recorded intermediate levels of the biochemical compounds between the Robusta and Arabica co...
Frontiers in Plant Science
Striga hermonthica is the most important parasitic weed in sub-Saharan Africa and remains one of ... more Striga hermonthica is the most important parasitic weed in sub-Saharan Africa and remains one of the most devastating biotic factors affecting sorghum production in the western regions of Kenya. Farmers have traditionally managed Striga using cultural methods, but the most effective and practical solution to poor smallholder farmers is to develop Striga-resistant varieties. This study was undertaken with the aim of identifying new sources of resistance to Striga in comparison with the conventional sources as standard checks. We evaluated 64 sorghum genotypes consisting of wild relatives, landraces, improved varieties, and fourth filial generation (F4) progenies in both a field trial and a pot trial. Data were collected for days to 50% flowering (DTF), dry panicle weight (DPW, g), plant height (PH, cm), yield (YLD, t ha−1), 100-grain weight (HGW, g), overall disease score (ODS), overall pest score (OPS), area under Striga number progress curve (ASNPC), maximum above-ground Striga (NS...
Crop Science
Sorghum (Sorghum bicolor [L.] Moench) is the fifth most important cereal crop worldwide and secon... more Sorghum (Sorghum bicolor [L.] Moench) is the fifth most important cereal crop worldwide and second after maize (Zea mays L.) in Kenya. It is an important food security crop in arid and semi-arid lands, where its production potential is hampered by drought. Drought tolerance can be measured by a plant's ability to resist premature senescence, often described as stay-green. This study was carried out with the objective of identifying novel stay-green trait among wild and landrace genotypes of sorghum. Forty-four sorghum genotypes that included 16 improved, nine landraces, and 17 wild relatives of sorghum alongside known stay-green sources, B35 and E36-1, were evaluated under well-watered and water-stressed conditions in an alpha-lattice design of three replications. Data was collected on plant height (PHT), flag leaf area (FLA), panicle weight (PWT), 100-seed weight (HSW), relative chlorophyll content (RCC), number of green leaves at maturity (GLAM), days to 50% flowering (DFL), and grain yield (YLD). Genetic diversity was determined using diversity arrays technology (DArT) sequencing and quality control (QC) markers were generated using a java script. Lodoka, a landrace, was the most drought-tolerant genotype, recorded the highest numbers of RCC and GLAM, and outperformed B35 and E36-1 in yield under water-stress and well-watered conditions. The RCC was highly correlated with GLAM (r = .71) and with yield-related traits, HSW (r = .85), PWT (r = .82), and YLD (r = .78). All traits revealed high heritability (broad-sense) ranging from 60.14 to 98.4% for RCC and DFL, respectively. These results confirm earlier reports that wild relatives and landraces are a good source of drought tolerance alleles.
Journal of Agricultural Science
Analysis of the gene action exhibited by an agronomic trait in crop plants is useful in the plann... more Analysis of the gene action exhibited by an agronomic trait in crop plants is useful in the planning of an effective plant breeding program. This study sought to establish the inheritance variance of root yield components and beta carotene content present in sweet potato clones commonly grown in Kenya. Ten contrasting parents were selected based on their beta carotene content, dry matter content and yield potential. They were planted in pots in the green house at KEPHIS-Muguga, Kenya, where they were grafted into Ipomoea setosa to boost their ability to flower. Five parents were further selected based on their ability to flower under local environmental conditions and crossed in a 5 × 5 half diallel manner. Five parents and ten F1 clones arising from this hybridization were evaluated at KALRO-Kiboko, Kenya during two rainy seasons. The field trials were laid out in a randomized complete block design of three replications. The data were scored for root yield characteristics, beta car...
Advances in Social Sciences Research Journal
Sorghum is an under-utilized crop and one of the most important cereal crops in semi-arid tropics... more Sorghum is an under-utilized crop and one of the most important cereal crops in semi-arid tropics. In Kenya, sorghum is grown in the often drought prone marginal agricultural areas of Eastern, Nyanza and Coast regions where there are many biotic and abiotic constraints that reduce its productivity. The aim of the present study was to assess the current utilization and processing practices by small holder farmers. Makueni County, a representative of drought prone areas situated in agro-ecological zone was selected since sorghum is a widely cultivated crop and the region has organized formally registered farmer groups. Key informant interviews (20), household survey questionnaires (300) and focus group discussions (12) with the farmers were conducted to gather data on sorghum production, challenges in production consumption and utilization, processing technology and market access. Key informant interviews (20), household survey questionnaires (300) and focus group discussions (12) wit...
February 2020
In Kenya, the key abiotic stress affecting rice production is drought stress which is experienced... more In Kenya, the key abiotic stress affecting rice production is drought stress which is experienced mainly during reproductive phase of the crop. This study evaluated the performance of Kenyan rice populations including 19 generation of crosses, 6 parental and 5 checks under well-watered and drought stressed environment with the aim of identifying the phenotypic traits that confer drought tolerance in rice. The 19 generation of crosses were in F3 when they were evaluated in the short rains season and later advanced to F4 in the long rains season. Nineteen generation of crosses rice (Oryza sativa L.) lines, six parental and five check lines were evaluated for response to drought under drought stressed and well-watered environment. The study was conducted over two seasons in the year 2016/2017 at Kenya Agricultural Livestock Research Organization (KALRO) -Mwea Centre. The experiment was set up in an alpha lattice design with three replications. Drought stress was imposed at panicle init...
Journal of Plant Studies
Sweet potato is one of the most important staple crops in Sub-Sahara Africa because of its supply... more Sweet potato is one of the most important staple crops in Sub-Sahara Africa because of its supply of carbohydrates, vitamin A and C, fiber, iron, potassium and protein.The objective of this study was to determine phenotypic variation in diverse sweetpotato varieties for marketable roots, fresh root yield, fresh biomass weight, harvest index, beta carotene content and root dry matter content. Twenty five sweet potato genotypes were evaluated at two sites in two seasons in Kenya using a randomized complete block design of three replications. The results indicated that there were highly significantly variations for genotypes and sites for all the traits studied. There were no significant differences for genotype x site x season effects for the traits except for the number of marketable roots and fresh root yield. The mean fresh root was 32.19 t/ha,with the genotype Ininda expressing the highest fresh root yield of 54.79 t/ha. Genotypes, Naspot 13, Ejumula, Kabode, Vitaa and Tio-Joe gav...
Journal of Agricultural Science
Cassava mosaic disease (CMD) caused by Bemisia tabaci is among the major contributors to low cass... more Cassava mosaic disease (CMD) caused by Bemisia tabaci is among the major contributors to low cassava yield in Africa and therefore requires instituting control measures. Due to genetic diversity in cassava, only clones with superior agronomic traits, disease resistance and high yield are selected and released to farmers or deployed in breeding program. This study was conducted to evaluate the resistance of cassava half-sib families to CMD. Field trials were conducted at Kenya Agricultural and Livestock Research Organization (KALRO), at Kakamega and Alupe research stations in western Kenya from June 2016 to June 2017. Sixty progenies were compared to that of their five parents by planting cuttings in 4 × 2 meters plots. Data were collected on plant height, number of roots per plant, harvest index, root yield, dry matter content, cassava mosaic disease and whiteflies infestation. Twenty three genotypes had a mean score of 1.0 to CMD, implying that they are resistant. Cassava gro...
Journal of Agricultural Science, 2017
Sorghum (Sorghum bicolour (L.) Moench), the most important cereal crop in Eritrea, is grown in mo... more Sorghum (Sorghum bicolour (L.) Moench), the most important cereal crop in Eritrea, is grown in more than 210,000 ha annually but its productivity is hampered by many factors including: farmer perception, lack of appropriate varieties, undeveloped seed systems, drought stress and Striga infestation. This study was aimed at understanding the sorghum smallholder livelihoods, farming systems, Striga incidence and infestation levels, and types of varieties grown in Striga infested sorghum growing areas. A semi structured questionnaire and focused group discussions were used to gather information from a total of 136 randomly selected farmers from three Striga endemic sub-regions of Eritrea namely, Hamelmalo, Goluj, and Tesseney. The results indicated that the most important cereal crops in the study area were sorghum, pear millet, ground nut and sesame. The most important constraint to sorghum production was identified as drought stress followed by Striga infestation. The majority of the ...
American Journal of Plant Sciences, 2016
Sorghum (Sorghum bicolour (L.) Moench), the second most important staple crop in Sub-Saharan Afri... more Sorghum (Sorghum bicolour (L.) Moench), the second most important staple crop in Sub-Saharan Africa (SSA) after maize, is well adapted to marginal environments of drought stress and high temperatures. But besides drought stress, the obligate root-parasitic flowering plant Striga hermonthica is an equally economically important biotic stress in agro-ecological zones where soils are marginal. Notwithstanding widespread and intense Striga infestation, genetic variations in defence mechanisms against the parasite have been reported. Sorghum variants, producing low levels of chemical stimulants such as sorgolactones that deter the advance of Striga seed germination and are therefore deemed resistant to the parasite, have been also reported in a few studies. But the existence of sorghum genetic variation for this resistance especially among farmers' landraces is yet to be demonstrated. The objective of this study was therefore to determine the levels of Striga germination stimulants in response to each of the 111 collected sorghum landraces and their progenies from Eritrea. The ability of a sorghum genotype to cause germination of a Striga seed as a measure of the amount of the germination stimulant produced was used to assess the resistance of these accessions. The data were recorded as Striga germination percentage by counting the number of germinated Striga seeds.
American Journal of Experimental Agriculture, 2016
Aims: This study characterized biochemical compound variability that influence green bean quality... more Aims: This study characterized biochemical compound variability that influence green bean quality in C. canephora as a basis for identifying heterogeneous genotypes for use in crop improvement because genetic erosion aided by climate change effects is gradually threatening the cultivation of Original Research Article
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Papers by Prof Kahiu Ngugi