Browsing by Author "Mamati, George E."
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Item 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.Item 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.Item 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.Item 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.Item 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.Item 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.Item 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