DSpace Repository :: Browsing by Author "Gichuru, E. K."

Browsing by Author "Gichuru, E. K."

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Biochemical Composition Within Coffea arabica cv. Ruiru 11 and Its Relationship With Cup Quality
(Canadian Center of Science and Education, 2014-01-14) Gichimu, Bernard M.; Gichuru, E. K.; Mamati, George E.; Nyende, A.B.
Biochemical composition appears to be influenced by both genetic factors and plant growth conditions. The main objective of this study was to evaluate the biochemical composition of selected Ruiru 11 sibs and its relationship with cup quality. Thirty four (34) Ruiru 11 sibs grown in three different locations in Kenya were used in this study. The experiment was laid out in a Randomized Complete Block Design with three replications. Coffee cherries were picked during the peak harvesting period between 2009 and 2011. The cherries were wet processed and graded into different grades based on size, shape and density. Fifty (50) grams of the dry coffee beans per sib per replication were frozen at -80 ºC before grinding (< 0.5 mm particle size) in liquid nitrogen as specified by the Association of Official Analytical Chemists (AOAC). The samples were packed in small plastic bottles and stored at -80 ºC awaiting extraction of biochemical components. Caffeine, trigonelline and total chlorogenic acids were extracted and purified using classical methods and analysed using High Pressure Liquid Chromatography (HPLC). For the lipids, the sample was subjected to Soxhlet extraction using n-hexane. The study demonstrated the existence of high variation in biochemical composition among Ruiru 11 sibs. Significant correlations were observed between biochemical and cup quality traits indicating that biochemical composition plays a major role in determining the sensory quality of coffee. The growing environment was also found to have an effect on biochemical composition as portrayed by high locational variations.
Combining CBD Resistance with High Yields and Good Cup Quality: Success case in Ruiru 11 Cultivar
(2015) Gichimu, Bernard M.; Gichuru, E. K.; Mamati, G. E.; Nyende, A. B.
Coffea arabica cv. Ruiru 11 is a composite of sixty six (66) F1 hybrid sibs each derived from a cross between a specific female and male population. The pedigree of Ruiru 11 consist of CBD resistance donors, Rume Sudan (R gene), Hibrido De Timor (T or Ck-1 gene), Catimor (T or Ck- 1 gene), K7 (k gene), SL4 and the high yielding, good quality but susceptible cultivars such as N39, SL28, SL34 and Bourbon. Ruiru 11 sibs reportedly present significant variability in terms of resistance to CBD, yields and quality. The objective of this study was to select for CBD resistance, high cherry yields and good quality within Coffea arabica L. cultivar, Ruiru 11. Thirty four hybrid sibs of Ruiru 11 cultivar grown in three different locations in Kenya were used for the study. The experiment was conducted between 2009 and 2011. Ripe cherries were harvested, bulked per replication, weighed and yield data recorded before subjecting them to wet processing, drying, hulling and grading. Beverage quality was determined following the sensory evaluation procedure of Specialty Coffee Association of America (SCAA). Evaluation of CBD resistance was conducted in the laboratory using hypocotyl inoculation method. The study confirmed earlier reports that Ruiru 11 sibs differ in quality aspects, yields and resistance to CBD but some sibs that combine all these desirable traits were identified.
Discrimination of Ruiru 11 Hybrid Sibs based on Raw Coffee Quality
(2015) Gichimu, Bernard M.; Gichuru, E. K.; Mamati, G. E.; Nyende, A. B.
Early Agronomic Performance of Some New and Existing Arabica Coffee Varieties in Kenya
(2015) Gichimu, Bernard M.; Omindi, C. O.; Gichuru, E. K.
The primary goal of plant breeding is to improve yield, quality and disease resistance. However, majority of reported work on coffee breeding primarily concerns agronomical improvement that directly impinges on either coffee quality or yields. The main objective of this study was to compare the agronomic traits of new Arabica coffee varieties with existing commercial cultivars in Kenya. Field recording of cherry yield and disease infection was done during the cropping seasons of 2007 and 2008. Artificial inoculation for both Coffee Berry Disease (CBD) and Coffee Leaf Rust (CLR) were done in respective screening laboratories using Completely Randomized Design (CRD). Significant variations in yield and disease resistance were observed among the genotypes. There were significant negative correlations between disease scores (both CBD and CLR) and cherry yield.
Genetic Characterization of Arabusta Coffee Hybrids and their Parental Genotypes using Molecular Markers
(2015) Gimase, J. M.; Thagana, W. M.; Kirubi, D. T.; Gichuru, E. K.; Gichimu, Bernard M.
Twenty coffee genotypes were characterized comprising of eleven F1 interspecific Arabusta hybrids, three induced tetraploid Robusta parental genotypes, four Arabica parental genotypes, one diploid Robusta accession and one Hybrido de Timor (HDT), a natural interspecific hybrid between Arabica and Robusta. Characterization was conducted using thirteen Simple Sequence Repeats (SSR) and ten Random Amplified Polymorphic DNA (RAPD) molecular markers. The molecular data were analyzed for polymorphism and also subjected to cluster analysis using Unweighted Pair Group Method with Arithmetic Average (UPGMA) to estimate the diversity among the genotypes. SSR markers revealed a genetic diversity of 51.5%, 50% and 6.9% while RAPD markers revealed genetic diversity of 51.6%, 47.4% and 3.5% within induced tetraploid Robusta, F1 interspecific Arabusta hybrids and Arabica genotypes respectively. The SSR primers separated the genotypes into 3 distinct clusters unlike RAPDs which separated them into 7 distinct clusters. The study therefore confirmed the narrow genetic base within Arabica coffee and successfully portrayed the possibility of broadening it through interspecific hybridization. These results can be used to select parents with high combining ability in a hybridization program between Arabica and tetraploid Robusta.
Genetic diversity among commercial coffee varieties, advanced selections and museum collections in Kenya using molecular markers
(Academic Journals, 2012-02) Gichimu, Bernard M.; Kathurima, CW.; Kenji, GM.; Muhoho, SM.; Boulanger, R.; Gichuru, E. K.
Molecular markers have effectively been applied to study genetic diversity and as markers of particular traits. This study assessed the diversity of twenty four (24) coffee genotypes using 10 Random Amplified Polymorphic DNA (RAPD) primers and 2 microsatellites (M24 and Sat 235). A total of 35 polymorphic bands were generated by the RAPD primers. The bands were scored for presence (1) and absence (0) of amplified products. The data was subjected to cluster analysis using R statistical software and a dendrogram constructed using Unweighted Pair Group Method with Arithmetic Average (UPGMA). The genotypes separated into three main clusters. C. eugenioides clustered alone in the first cluster while un-introgressed Arabica genotypes dominated the second cluster. The third cluster comprised of Coffea canephora (Robusta) and introgressed genotypes, Ruiru 11, Hibrido de Timor and Catimor. Robusta and C. eugenioides were the most distantly related and generated most of the diversity observed. The similarities observed among un-introgressed Arabica genotypes attest to the narrow genetic diversity within Coffea arabica. The divergence observed among introgressed genotypes could be utilized in future breeding programmes.
Methods for early evaluation for resistance to bacterial blight of coffee
(Academic Journals, 2013) Gichimu, Benson M.; Cheserek, J. J; Gitonga, P. N.; Gichuru, E. K.; Ithiru, J. M.
Bacterial Blight of Coffee (BBC) caused by Pseudomonas syringae pv garcae has become of major concern in Kenya due to its increasing incidence and severity. For decades, the disease was confined within and to the west of the Great Rift Valley, but recently it has spread to reach other coffee growing areas. In order to minimize the chemical input in its management, which apart from polluting the environment have high cost implications, development of resistant/tolerant cultivars is highly recommended. This study aimed at developing an effective method(s) for early evaluation of resistance to BBC and to use the method(s) to evaluate the reaction of selected coffee genotypes to different isolates of P. syringae pv garcae. Three isolates from different coffee growing areas in Kenya were used to inoculate thirteen coffee genotypes using injection and cut methods. The two inoculation methods were found to be effective and can be recommended with slight modifications. However, it was not possible to clearly authenticate the reaction of the different genotypes to BBC since the genotypes responded differently to different isolates and inoculation methods.
Occurrence of Ck-1 gene conferring resistance to Coffee Berry Disease in Coffea arabica cv. Ruiru 11 and its parental genotypes
(Scienceweb Publishing, 2014-03) Gichimu, Bernard M.; Gichuru, E. K.; Mamati, George E.; Nyende, A.B.
Resistance to Coffee Berry Disease (CBD) in Coffea arabica cv. Ruiru 11 is known to be controlled by among others, the T (Ck-1) gene from Robusta coffee (Coffea canephora Pierre). The cultivar reportedly presents significant variability in resistance to CBD. Previous work identified a microsattelite marker Sat 235 which was linked to CBD resistance and mapped it onto the introgressed C. canephora fragment which carries the Ck-1 gene. This study was aimed at utilizing the Sat 235 marker to assess the occurrence of the Ck-1 gene in Ruiru 11 sibs and their parental genotypes. The test genotypes used were CBD resistant Robusta coffee, non introgressed C. arabica cv. caturra, 14 Ruiru 11 parental genotypes with varying reaction to CBD and 34 Ruiru 11 sibs. Evaluation of CBD resistance was conducted in the laboratory using hypocotyl inoculation method. Seeds of the test genotypes were sown in plastic boxes filled to half-depth with sterilized river sand and arranged in a completely randomized design with three replications. Six weeks after sowing, the seedling hypocotyls were inoculated with a conidial suspension of C. kahawae standardized to 2.0 × 106 spores/ml. Disease scoring was conducted 4 weeks after inoculation on a scale of 1 to 12. To confirm occurrence of the Ck-1 gene, genomic DNA was then extracted from the test genotypes and amplified with the microsatellite primer Sat 235 and electrophoresed on a 6% denaturing polyacrylamide gel. All the genotypes containing the Ck-1 gene were expected to show phenotypic resistance to CBD and to show similar banding pattern as Robusta and HDT while the ones lacking the gene were expected to show phenotypic susceptibility to CBD and to similar banding pattern as Caturra and SL28. The study observed that all Ruiru 11 sibs that were evaluated contained the Ck-1 gene. The study also provided further evidence that the fragment amplified by SSR primer Sat 235 is linked to CBD resistance.
Occurrence of Ck-1 gene conferring resistance to Coffee Berry Disease in Coffea arabica cv. Ruiru 11 and its parental genotypes
(SCIENCEWEB PUBLISHING, 2014-03) Gichimu, Bernard M.; Gichuru, E. K.; Mamati, George E.; Nyende, A.B.
Abstract. Resistance to Coffee Berry Disease (CBD) in Coffea arabica cv. Ruiru 11 is known to be controlled by among others, the T (Ck-1) gene from Robusta coffee (Coffea canephora Pierre). The cultivar reportedly presents significant variability in resistance to CBD. Previous work identified a microsattelite marker Sat 235 which was linked to CBD resistance and mapped it onto the introgressed C. canephora fragment which carries the Ck-1 gene. This study was aimed at utilizing the Sat 235 marker to assess the occurrence of the Ck-1 gene in Ruiru 11 sibs and their parental genotypes. The test genotypes used were CBD resistant Robusta coffee, non introgressed C. arabica cv. caturra, 14 Ruiru 11 parental genotypes with varying reaction to CBD and 34 Ruiru 11 sibs. Evaluation of CBD resistance was conducted in the laboratory using hypocotyl inoculation method. Seeds of the test genotypes were sown in plastic boxes filled to half-depth with sterilized river sand and arranged in a completely randomized design with three replications. Six weeks after sowing, the seedling hypocotyls were inoculated with a conidial suspension of C. kahawae standardized to 2.0 × 106 spores/ml. Disease scoring was conducted 4 weeks after inoculation on a scale of 1 to 12. To confirm occurrence of the Ck-1 gene, genomic DNA was then extracted from the test genotypes and amplified with the microsatellite primer Sat 235 and electrophoresed on a 6% denaturing polyacrylamide gel. All the genotypes containing the Ck-1 gene were expected to show phenotypic resistance to CBD and to show similar banding pattern as Robusta and HDT while the ones lacking the gene were expected to show phenotypic susceptibility to CBD and to similar banding pattern as Caturra and SL28. The study observed that all Ruiru 11 sibs that were evaluated contained the Ck-1 gene. The study also provided further evidence that the fragment amplified by SSR primer Sat 235 is linked to CBD resistance.
Quantitative trait loci (QTL) mapping of resistance to coffee berry disease (Colletotrichum kahawae Waller & Bridge) in Coffea arabica L. variety Rume Sudan
(Academic Journals, 2020-06) Gimase, James M.; Thagana, Wilson M.; Omondi, Chrispine; Cheserek, Jane Jerono; Gichimu, Bernard M.; Gichuru, E. K.
Coffee Berry Disease (CBD) is a major constraint that limits Coffea arabica production, whose resistance is governed by three genes, T, R that are dominant and recessive k in varieties Hibrido de Timor (HDT), Rume Sudan (RS) and K7 respectively. This study identified the genomic region occupied by R-gene using F2 genotypes from varieties RS and SL28; and Single Nucleotide Polymorphic (SNP) markers obtained through Genotyping by Sequencing. Redundant markers were removed and 699 markers obtained for linkage mapping and quantitative trait loci (QTL) analysis. The Linkage map spread over 5525.39 cM across eleven coffee chromosomes (Chr). The QTL was analyzed by both Interval Mapping (IM) and Inclusive Composite Interval Mapping (ICIM) using SNP markers and CBD resistance mean scores of the F2 genotypes and their parents. Three QTLs, qCBD 1-1 in Chr 1, qCBD 2-1 and qCBD 2-2 in Chr 2 were significantly associated with CBD resistance, detected by both IM and ICIM at LOD ≥ 2.5 (P≤0.05). Two flanking markers that were closer to the three QTLs; 100025973|F|0-59:T>C59:T>C at a distance of 3 centi Morgans (cM) from qCBD 1-1 and 100034991|F|0-44:C>T-44:C>T, that was flanking in both qCBD 2-1 and qCBD 2-2 at 12.5 cM, whose SNPs were significant (P≤0.05), are recommended for validation and use in marker-assisted breeding.
Selection of Ruiru 11 hybrid sibs on raw coffee quality
(2012-06) Gichimu, Bernard M.; Gichuru, E. K.; Mamati, George E.; Nyende, A.B.
The economic value of Arabica coffee (Coffea arabica L.) is determined mainly by the yield potential, the size and shape of raw beans and beverage quality. Bean quality reportedly differ depending on the variety, environmental conditions and management practices. This study aimed at genetically improving raw bean quality of C. arabica cultivar Ruiru 11 through selection within the cultivar. The study also intended to measure the extent to which raw bean quality of Ruiru 11 is affected by the environment. Thirty four Ruiru 11 full-sibs grown in three locations in Kenya exhibiting strong edaphic and climatic differences were used for the study. The three sites were Mariene in Meru, Kisii and Koru. Rainfall amounts during various phases of berry development were used to explain the differences observed in discriminating abilities of the locations for raw bean quality traits. The results showed that beans of desirable AA and AB grades were obtained from Mariene where moderate moisture supply was received during berry expansion and bean filling stages rather than in high rainfall conditions. The best overall Ruiru 11 sibs were identified as R11-121, R11-93, R11-142, R11-52 and R11-71.
Selection within Coffea arabica cv. Ruiru 11 for high cup quality
(Academic Journals, 2012-09-26) Gichimu, Bernard M.; Gichuru, E. K.; Mamati, George E.; Nyende, A.B.
In recent years, consumer awareness about the quality of different coffees has increased and therefore production and supply of coffee with excellent quality attach more significance. As a result, many coffee producing countries include coffee quality assessment in their coffee variety development programmes. The present study was undertaken to evaluate the variation of cup quality traits and determine their associations with each other and with overall cup quality among the sibs of Coffea arabica L. cultivar Ruiru 11. In addition, the study targeted to select specific Ruiru 11 sibs with superior cup quality and wide adaptability based on assessment of 7 traits including fragrance, flavor, aftertaste, acidity, body, balance, preference and their total score. Thirty four full-sib families representing this hybrid cultivar grown in three different agro climatic zones of Kenya were used for the study. Rainfall amounts during various phases of berry development were used to explain the differences observed in the discriminating abilities of the locations for cup quality traits. The results showed that Ruiru 11 sibs were highly variable in all the cup quality traits except body. Site variations were also highly significant and the sibs were best differentiated in the sites where moderate moisture stress occurred during bean expansion and filling stages. Genotype by environment (G × E) interactions, were observed for all the traits except body. A highly significant positive correlation was registered between all traits. The study also demonstrated the existence of a high variation in cup quality among Ruiru 11 sibs. The most widely adapted Ruiru 11 sibs were identified to be R11-52, R11-117, R11-131, R11-107, R11-121, R11-11, R11-137 and R11-22.
Variation and Association of Cup Quality Attributes and Resistance to Coffee Berry Disease in Coffea Arabica L. Composite Cultivar, Ruiru 11
(2013-12) Gichimu, Bernard M.; Gichuru, E. K.; Mamati, George E.; Nyende, A.B.
Majority of reported work on coffee breeding primarily concerns agronomic improvement that directly impinges on coffee quality. However, it is crucial that coffee breeding programmes for disease resistance also include coffee quality improvement since consumer awareness about the quality of different coffees has increased. The aim of this study was to determine the variation and associations of cup quality parameters and resistance against Coffee Berry Disease (CBD) in Coffea arabica L. cultivar Ruiru 11 hybrid sibs. The study also aimed at selecting specific Ruiru 11 sibs that combines good cup quality with high CBD resistance. Thirty four full-sib families representing this hybrid cultivar grown in three different agro climatic zones in Kenya were used for the study. Evaluation of CBD resistance was conducted through hypocotyl inoculation in a laboratory set-up. The study demonstrated existence of a high variation in cup quality and CBD resistance among Ruiru 11 sibs. A highly significant positive correlation was observed between all cup quality traits but there was either negative or no correlation between most cup quality traits and CBD resistance.
Yield Selection within Coffea arabica cv. Ruiru 11
(SCIENCEDOMAIN international, 2012-08-17) Gichimu, Bernard M.; Nyende, A.B.; Gichuru, E. K.; Mamati, George E.
Aims: This study was aimed at identifying high yielding Ruiru 11 sibs in varying growing conditions. The study also intended to measure the extent to which cherry yields of Ruiru 11 are affected by the environment. Study Design: Randomized Complete Block Design with three replications. Place and Duration of Study: The study was conducted in three different agro-ecological zones in Kenya namely Mariene in Meru County, Kisii near Kisii town in Kisii county and Koru in Kericho County between November 2008 and September 2011. Methodology: Thirty four (34) Ruiru 11 sibs, all of which are resistant to Coffee Berry Disease and Coffee Leaf Rust, were evaluated in this study alongside two entries of SL28, a cultivar susceptible to the two diseases. One entry of SL28 was sprayed with copper fungicides to control, while the other SL28 entry was not sprayed with any fungicides. Planted at a spacing of 2m by 2m, each entry had 12 trees per plot per rep, giving a total of 1296 plants per experiment per site. Cherry yield recording was done during the peak harvesting period of May to July at Mariene and July to September at Koru and Kisii. The data was subjected to Analysis of Variance (ANOVA) using XLSTAT version 2012 statistical software and effects declared significant at 5% level. Results: Significant (P = .05) yield differences among Ruiru 11 sibs were obtained in all years of evaluation at Koru but only in 2011 at Kisii and Mariene. There was a greater discrimination between sibs at Koru, followed by Kisii and then Mariene. Year effect was highly significant (P < .001) and equally distinguished in all sites but year x sib interactions were significant (P = .05) only at Kisii. Combined analysis for all environmental combinations showed highly significant (P < .001) differences between sibs, environments and their interaction. Environments made a greater contribution (42.6%) to the variation compared to sibs (7%). The interaction term also made a significant contribution (18.7%). The best sibs per site and those adapted to contrasting environments were identified. Conclusion: The expression of high yield variation among Ruiru 11 sibs is a sign of high potential of intra-selection within the cultivar for yield improvement. Identified sibs can be recommended to farmers and also exploited in future breeding programmes for improvement of Ruiru 11 productivity and agronomic adaptability. The occurrence of significant sib by environment (G x E) interactions

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