Browsing by Author "Njoka, Fredrick M."
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Item Agronomic Performance of Single Crosses of Maize in Kiambu and Embu Counties of Kenya(2017-06) Njoka, Fredrick M.; Kariuki, Jeniffer M.Aims: This study was conducted to determine the agronomic performance of respective maize single crosses in different environments in varying soil and climatic zones in Kenya. Methodology: The trials were conducted at experimental stations of Kenya Agricultural and Livestock Research Organization (KALRO), Muguga South and KALRO Embu in Kiambu and Embu counties of Kenya respectively. The germplasm used in this study were 36 single crosses among 18 inbred lines of maize. The experiment was laid out in a 6 x 6 lattice randomized complete block design (RCBD) with two replications. Agronomic performance was measured by collecting and analyzing data on plant height, ear height, disease scores of maize streak virus and gray leaf spot and grain yield. Data was subjected to analysis of variance (ANOVA) using Genstat 12 program for individual single crosses. Mean separation was done using Tukey’s comparison method at 5% significance level. Results: The best performing crosses in Muguga were also the best in Embu on grain yield production with exception of cross MUL 516 x MUL508 which had a mean grain yield of 11.9 t/ha in Muguga but produced 2.7 t/ha in Embu which was attributed to other factors other than genetic makeup. Variation in yield showed a diverse genetic background of genotypes studied under these conditions. The grain yield ranged between 1.01 t/ha (MUL533 x MUL513) to 11.9 t/ha (MUL 516 x MUL 508) both in Muguga). The best performing cross for grain yield in Muguga was MUL 516 x MUL 508) while in Embu the best performing cross for grain yield was MUL541 x POPA. Data on disease scores where natural infestation was visually scored showed that majority of the crosses had a score of one confirming their near immunity status. Conclusions: For grain yield improvement crosses MUL508 x MUL688, POPA x MUL14, MUL513 x MUL114 and MUL513 x CN244 can further be evaluated and eventually released to farmers as they indicated promising relationship with yield potential compared to other crosses. Further research on agronomic performance of the crosses can be done not only in the research sites but also in other regions of Kenya.Item Combining Ability of Inbred Lines of Maize (Zea mays) in Kiambu and Embu Counties, Kenya(Science Domain International, 2016-08) Kariuki, J. M.; Njoka, Fredrick M.; Leley, P. K .; Manene, D. W.Despite the fact that virtually all households in Kenya grow maize, over 60% of them are net maize buyers because they do not produce enough for their consumption. This is due to both biotic and abiotic factors such as poor planting materials, diseases and unreliable weather among others. This study was conducted to select lines with good combining ability. The trials were conducted in 2012 at experimental stations of Kenya Agricultural and Livestock Research Organization (KALRO) Muguga South and Embu in Kiambu and Embu counties of Kenya respectively. The study was conducted with 18 inbred lines. The experiment was laid out in a 6 x 6 lattice incomplete randomized block design with two replications. In Embu inbred line POPA produced the best grain yields when crossed with MUL 541 and MUL 521. Its high grain yield was also witnessed in Muguga where on average its performance was superior to other inbred lines. Inbred line MUL 513 can further be evaluated for grain yield improvement with all the other inbred lines which had high grain yields. The best general combiners for grain yield were MUL 508, MUL 688, POP A, MUL 541, MUL 513 and MUL 114. POP A x MUL 541 produced the highest yield of 0.49 t/ha. Based on SCA estimates, the best cross combinations for plant height were MUL 508 x MUL 688, POP A x MUL541 and MUL513 x MUL114. For ear height best cross combinations were: MUL 508 x MUL 688, POP A x MUL 141, POP A x MUL 541 and MUL 513 x MUL 114. The best combinations for grain yield were MUL 508 x MUL 688, POP A x MUL 541 and MUL 513 x MUL 114. Crosses MUL508 x MUL 521, MUL 541 x MUL 508, and MUL 688 x MUL508 were good combinations for MSV disease resistance since in both research sites they had an MSV score of 1. For grain yield improvement on specific combining ability crosses MUL 508 x MUL 688, POP A x MUL 141, MUL 513 x MUL 114 and MUL 513 x CN244 can further be evaluated and eventually released to farmers as they indicated promising relationship with yield potential compared to other crosses. Crosses MUL 508 x MUL 516, POP A x MUL 141 and POP A x MUL 688 can further be evaluated for disease resistance. The results will be useful to breeders and farmers in selecting the potential parental materials for improvement in maize breeding programs.Item Determination of Post Striga Attachment Resistance in Selected Resistant Sorghum Lines in Kenya(International Knowledge Press, 2017-05) Manene, Diana W.; Njoka, Fredrick M.Breeding for Striga resistance in sorghum and other cereals is recognized as the most sustainable control measure, however there is a lack of cereal germplasm that exhibit post attachment to Striga that limits this noble approach. This study evaluated post attachment resistance levels of four Striga resistant sorghum (SRS) lines against four ecotypes of Striga from Kenya and Tanzania. Sorghum seeds were grown in rhizotrons (root observation chambers) and the seedlings were inoculated with pre-germinated Striga seeds and on emergence the attached parasites were harvested from the roots of sorghum and scored for the number of attachments, length and dry biomass. There was a significant difference in the biomass and average length of attached Striga seedlings among the three Kenyan ecotypes on all sorghum lines. The phenotype of a resistance mechanism was characterized by the inability of the parasite to penetrate host endodermis, necrosis and the browning and death of attached Striga seedlings. SRS 1208/2 had very high post- attachment resistance to the S. hermonthica ecotypes used in this study, SRS 2408 and SRS 2208 exhibited intermediate resistance while SRS 3308/5 had low resistance. The difference in biomass, number and length of attached Striga seedlings upon infection clearly indicated genetic variability for Striga resistance in the selected lines. Among the four sorghum lines studied, cultivar SRS 1208/2 was the most promising source of resistance to obligate root parasite S. hermonthica and can be recommended for future use in sorghum breeding programs in East Africa.Item Determination of Stem Rust Ug99 Disease Severity in Selected Wheat Backcrosses in Kenya(2017-05) Tubei, Jackline E.; Ombori, Omwoyo; Njau, Peter N.; Njoka, Fredrick M.Stem rust (Puccinia graminis tritici) is a disease of economic importance in wheat (Triticum aestivum L.) worldwide. The objective of this study was to determine the disease severity of the BC1F1 plants in the nursery at Kenya Agricultural and Livestock Research Organization, Njoro. Kingbird (resistant) was crossed with Njoro Bw2 (susceptible) to obtain F1 plants. The F1 plants were backcrossed with Njoro Bw2 to obtain a BC1F1 progeny. Two hundred and forty seeds of the BC1F1 plants, twenty eight resistant and susceptible parents were planted in two replicates and the Modified Cobb’s Scale was used to record their disease severity scores. An excel work sheet programmed with the AUDPC formula was used to compute the Area Under Disease Progress Curve (AUDPC) values for BC1F1 plants. Variation of the disease severity scores and mean AUDPC among the wheat plants was analysed using Analysis of variance (ANOVA). Results showed 47.9% of resistant plants that portrayed the pseudo black chaff (PBC) trait had low disease severity mean scores ranging from 0 to 1.0414 with mean AUDPC values below 99.8. The resistant plants without PBC were 43.3 % and had disease severity mean score ranging from 0.9098 to 1.3686 with mean AUDPC values ranging from 99.8 to 260.The BC1F1 plants that showed susceptibility to stem rust disease were 21 (8.8 %) and had the highest disease severity mean score ranging from 1.3223 to 1.4914 with the highest mean AUDPC values ranging from 282.5 to 431.3. The ANOVA computation showed that, variation in the disease severity and in the mean AUDPC values among the individual plants (P < 0.001) was significant, but variation in mean AUDPC values from one replicate to another (P > 0.001) was not significant. The BC1F1 wheat plants showed a low disease severity score in the field indicating that theseItem Genetic diversity of Faidherbia albida (Del.) A. Chev accessions held at the World Agroforestry Centre(Taylor & Francis, 2015-06) Kithurea, Robert K.; Muchugia, Alice; Jamnadassa, Ramni; Njoka, Fredrick M.; Mwauraa, LucyThis study assessed the extent and distribution of genetic diversity of 29 Faidherbia albida provenances from 10 African countries by employing amplified fragment length polymorphism with an aim of providing crucial genetic diversity information for in situ and ex situ management and utilization of the collections. Plant materials consisted of F. albida accessions held at World Agroforestry Centre [International Center for Research in Agroforestry (ICRAF)] seed bank. A total of 676 bands ranging from 50 to 499 base pairs were scored using five primer sets. The average percentage of polymorphic loci over all populations was 31.7. The collection from the Taveta (Kenya) provenance had the highest percentage of polymorphic loci (69.5%), while those from Manapools (Zimbabwe) had the lowest (13.5). The average heterozygosity ranged from 0.05 to 0.28 with a mean of 0.16 across all the provenances. There was high and quite significant population differentiation among the populations (PhipT ¼ 0.64, p ¼ 0.001). Analysis of molecular variance revealed that 64% of the total variation was partitioned among the populations and 36% within the populations. Unweighed pair-group method with arithmetic averaging clustering generally reflected the geographical origins and similarity of the germplasm except West African provenances indicating complex evolutionary trends that have shaped the population structure and distribution of the species. The results show that the germplasm held at ICRAF seed bank is of low genetic variability with the western and some of the eastern Africa provenances having the highest diversity. More collections need to be done to cover the entire distribution range of this species to capture more diversity and enrich this gene pool.Item Genetic variability analysis for growth and yield parameters in double cross maize (Zea mays l.) genotypes in Kitale county of Kenya(Science Journals Publishing, 2013) Melil, Charles K.; Ombakho, George; Omari, Odongo M.; Njoka, Fredrick M.Present study was conducted to select hybrids with improved yield, to identify testers for grain yield and to determine the magnitude of genetic variability in maize hybrids for yield and its elements. Adaptability of double cross hybrids was studied under varying agro-climatic conditions of parts of Western Kenya. Seventeen experimental hybrids and one commercial maize variety (standard) were planted in a 6x6 balanced lattice design with three replicates. Physiological and agronomic traits were observed and recorded from germination to maturity. Collected data was subjected to analysis of variance (ANOVA) using the general linear model SAS. The results showed that ear height ranged between 169.0 and 214.0 cm showed by genotype (95xF)x(50x82) and (95x8)x(50x16) respectively. The plant height ranged between 309.0 and 330.7 cm showed by genotype (44xA)x(50x93) and (44xA)x(82x93) respectively, grain weight ranged between 253.3 and 441.7 g showed by genotype (44xA)x(82x93) and (64x8)x(82x93) respectively, rows per cob ranged between 12.3 and 13.9 showed by genotype (95xF)x(82x16) and (Fx82)x(93x16) respectively. Grains per row ranged between 34.3 and 42.1 which was shown by genotype (AxF) x (50x82) and (95x8)x(50x16) respectively, the cob length ranged between 19.6 cm and 23.4 cm shown by genotype (56x44)x(50x93) and (95x8)x(50x16) respectively and the grain yield ranged between 5.2 and 12.8 t/ha produced by genotypes (95xF)x(82x16) and (56x44)x(50x16) respectively. Evaluating the various results revealed that genotype (56x44)x(50x16) and (95x8)x(50x16) were the most promising and their adaptation to the agro-ecological condition to this area can bring a substantial increase in maize grain yield.Item Genotype variant of soybean cultivars around Lake Victoria region, East Africa(2010-01) Okwany, Zedekiah A.; Njoka, Fredrick M.; Githui, ElijahGlycine gracilis, which originated from North-East China, is morphologically intermediate between the cultivated G. max and the wild form, G. soja. These three forms are cross-compatible and their crosses provide a resource for biologically and agronomically important genes. Breeding genetics of soybean has developed slowly due to inherent difficulties in crossing. The soybean stamens and the pistils are present in the same flower resulting in a high percentage of self-fertilization. The cultivars grown around the Lake Victoria differ in agronomic performance but their genotypes have not been described at the molecular level. Amplification of 5S ribosomal gene from the cultivars yielded uniform PCR product of about 700 bps. Limited sample sequencing showed a restriction marker site within the 5S ribosomal gene. A phylogenetic tree based on 5S rDNA gene sequences of East African cultivars and different Glycine species suggests that the cultivar Mikumi is similar to, and SB 19 of Kenya and Maksoy of Uganda are closely related to, G. max.Item Genotype X Environment Interaction of Inbred Lines of Maize (Zea Mays L.) and Stability of Crosses in Kiambu and Embu Counties, Kenya.(2016-05) Muriuki, J. M.; Njoka, Fredrick M.; Leley, P. K.; Manene, D. W.Despite the fact that virtually all households in Kenya grow maize over 60% of them are net maize buyers because they do not produce enough for their consumption. Kenya’s current food supply situation and outlook give cause for serious concern. Maize is the main staple food averaging over 80% of total cereals (rice, wheat, millet and sorghum) in Kenya. Maize stocks are estimated to be depleted at all levels throughout the country. Due to increasing temperatures as a result of global warming and consequent dropping of water table, there has been shortage leading to increased demand for maize and its products. This study was conducted to determine the stability of respective single crosses in different environments. The trials were conducted in 2012 at experimental stations of Kenya Agricultural and Livestock Research Organization (KALRO), Muguga South and KALRO Embu in Kiambu and Embu counties of Kenya respectively. The study was conducted with 36 crosses. The stability of crosses was determined and interaction between the genotypes and environment was also determined among the crosses.The experiment was laid out in a 6 x 6 lattice complete randomized block design (RBCD) with two replications. Data was subjected to analysis of variance (ANOVA) using Genstat 12 program for individual single crosses as well as for combined environments considering environments as random effects and crosses as fixed effects. Mean separation was done using Tukey’s comparison method at 0.05% significance level. Data on grain yield showed no significant difference between the sites but there was significant difference on grain yield. Data on disease scores where natural infestation was visually scored showed majority of the crosses had a score of one confirming their near immunity status. Further research on stability of the crosses can be done not only in the research sites but also in other regions of Kenya. For grain yield improvement crosses MUL508 x MUL688(entry 9), POPA x MUL141(entry 19), MUL513 x MUL114 (entry 31) and MUL513 x CN244 (entry 33) can further be evaluated and eventually released to farmers as they indicated promising relationship with yield potential compared to other crosses. The results will be useful to breeders and farmers in selecting the potential parental materials for improvement in maize breeding programs.Item Identifying Morpho-Physiological Characteristics Associated with Drought Tolerance in Selected Chikpea Germ Plasm in Nakuru and Baringo Counties, Kenya(2013-11) Kirui, Grace J.; Njoka, Fredrick M.tolerance based on a study of selected chickpea lines under field conditions in Nakuru and Baringo counties in Kenya. Drought has been spreading to more land in Kenya over the years due to climatic change attributed to global warming. Chickpea being drought resistant can act as a cereal-legume relay crop in dry highlands during the short rains as it improves soil fertility and conserves moisture. But currently there are no lines released for commercial production in Kenya, hence there is need to introduce and evaluate several lines to identify those that can do well in dry lands of Kenya. This study therefore screened several chickpea genotypes to identify and select drought tolerant lines with associated morpho-physiological characteristics under field conditions and determined their heritability. The study was conducted in two sites, at Koibatek-Farmers Training Centre for two seasons (during the short and long rains) and in KEPHIS-Lanet for one season (long rains). A mini core collection of 30 lines from ICRISAT was evaluated in the two sites in a Randomised Complete Block Design (RCBD), replicated twice. Parameters that were measured included phenological growth stages, yield (Kg/ha) and its components which included number of pods/plant, plant height (cm), plant spread (cm), biomass (Kg/ha), harvest index (HI). All data collected were analyzed using Analysis of Variance (ANOVA) using Genstat and means separated by Duncan Multiple Range Test (DMRT) at (P=0.05). The morphological traits associated with drought tolerance due to their direct contribution to yield included biological mass, days to physiological maturity, days to 50% flowering and % DTE. These traits could be of interest in improving chickpea since they could be genetically manipulated or improved due to their high genetic contribution to their phenotypic traits. There is need for further screening and breeding of the selected lines for drought toleranceItem Identifying Morpho-Physiological Characteristics Associated with Drought Tolerance in Selected Chikpea Germ Plasm in Nakuru and Baringo Counties, Kenya(2013-11) Kirui, Grace J.; Njoka, Fredrick M.This paper examines the morpho-physiological characteristics of chickpea associated with drought tolerance based on a study of selected chickpea lines under field conditions in Nakuru and Baringo counties in Kenya. Drought has been spreading to more land in Kenya over the years due to climatic change attributed to global warming. Chickpea being drought resistant can act as a cereal-legume relay crop in dry highlands during the short rains as it improves soil fertility and conserves moisture. But currently there are no lines released for commercial production in Kenya, hence there is need to introduce and evaluate several lines to identify those that can do well in dry lands of Kenya. This study therefore screened several chickpea genotypes to identify and select drought tolerant lines with associated morpho-physiological characteristics under field conditions and determined their heritability. The study was conducted in two sites, at Koibatek-Farmers Training Centre for two seasons (during the short and long rains) and in KEPHIS-Lanet for one season (long rains). A mini core collection of 30 lines from ICRISAT was evaluated in the two sites in a Randomised Complete Block Design (RCBD), replicated twice. Parameters that were measured included phenological growth stages, yield (Kg/ha) and its components which included number of pods/plant, plant height (cm), plant spread (cm), biomass (Kg/ha), harvest index (HI). All data collected were analyzed using Analysis of Variance (ANOVA) using Genstat and means separated by Duncan Multiple Range Test (DMRT) at (P=0.05). The morphological traits associated with drought tolerance due to their direct contribution to yield included biological mass, days to physiological maturity, days to 50% flowering and % DTE. These traits could be of interest in improving chickpea since they could be genetically manipulated or improved due to their high genetic contribution to their phenotypic traits. There is need for further screening and breeding of the selected lines for drought tolerance.Item Introgression of Stem Rust Resistance into Popular Kenyan Wheat Varieties to Improve Production(2018-02) Jackline, Tubei E.; Njoka, Fredrick M.; Ombori, Omwoyo; Njau, Peter N.Aim: The objective of this study was to assess the introgression of the stem rust resistance genes into the BC1F1 plants using molecular markers. Place and Duration of Study: Field experiments were carried out in a nursery, at Kenya Agricultural and Livestock Research Organization (KALRO) Njoro Centre, Nakuru, Kenya at 0.3ºS and 35.9ºE and 2185 m above sea level from June 2012 to December 2013. Laboratory work was carried out in the Biotechnology laboratory, KALRO Njoro. Methodology: Polymerase Chain Reaction (PCR) amplifications were carried out to assess the introgression of stem rust resistance genes into the BC1F1 plants. Analysis of genetic variation was done at each locus in terms of the number of alleles observed, heterozygosity, expected heterozygosity, Shannon's diversity index, genetic diversity and gene frequency using genetic analysis package POPGENE Version 1.32. The neighbouring joining method was used to construct a dendrogram from a distance matrix based on Sokal and Michener’s genetic distances, using MEGA4 software 1in Power Marker 3.25. Results: Amplification using PCR showed that wheat BC1F1 plants accessions NP3, NP12, NP89, NP163, NP192 and Kingbird were positive for the Lr34 gene while the susceptible plants and Njoro Bw2 were negative. Evaluation done on three molecular markers showed that CSLV34 was polymorphic across the BC1F1 plant accessions with a total of 2 alleles per locus. The 17 wheat BC1F1 plant accessions and their parents (Njoro Bw2 and Kingbird) were placed into 2 clusters using the markers as a result of introgression, considering that the clustering in this study was purposively based on the presence or absence of the resistance genes. This indicates that the Lr34 gene which is an APR gene was successfully introgressed into five BC1F1 accession plants (NP3, NP12, NP89, NP163 and NP192). Conclusion: The resistant BC1F1 accession plants (NP3, NP12, NP89, NP163 and NP192) showed success in the introgression of the Lr34 gene that gives resistance to stem rust at adult plant stage together with other minor genes including Sr2 and Lr46. These can further be developed in the field, multiplied and the seeds distributed to the farmers as they showed low disease severity to stem rust diseaseItem Molecular genotyping of selected soybean (Glycine max L.) genotypes grown in different regions of East Africa(2010) Njoka, Fredrick M.; Okwany, Z.A.; Githui, E.K.Soybean (Glycine max (L.) Merril) is one of the most popular pulses because of its protein content and nodulating ability. However, most farmers and researchers do not have sufficient genetic information of the genotypes that they grow. This research aimed at determining the molecular characteristics of selected soybean genotypes grown in different regions of East Africa and make recommendations to the farmers and researchers. Genotypes were collected from Uyole, Ukiriguru, Kawanda, Namulonge, Njoro and Embu Agricultural Institutes as well as from farmers. Molecular analysis was done by DNA being extracted according to phenol chloroform method. This was followed with PCR process using custom ordered pair of primers that corresponded to the flanking ends of the targeted gene fragment (5S ribosomal genes). Restriction fragment length polymorphism (RFLP) and gene clean were then performed on the isolated PCR fragments. The elute was confirmed on agarose gel then sent for automated sequencing ABI prism (Applied Biosystems) at ILRI. The resulting gene sequences were compared with gene sequences of known Glycine species using various enzymes in computer based simulations. The gene sequences were then subjected to gene blast using MEGA 4 and resulted with a phylogenetic tree for the selected East African soybean. The studied cultivars were found to be closely related to Glycine max species. Enzyme Sac11 was identified as a marker for the East African soybean genotypes. These results may also assist plant breeders to produce hybrids with the best performing cultivars based on their genetic diversity.Item Pathogenicity of Colletotrichumkahawae in Kenya(2017-05) Njoka, Fredrick M.; Owaka, Margaret; Omondi, Chrispine; Kathurima, ElijahThis study was aimed at determining the virulence diversity of Colletotrichumkahawae, and their correlation with coffee growing regions and interaction with coffee varieties in Kenya. A total of 34 single conidia isolates were obtained and subjected to variation analysis using DNA banding patterns. The test varieties included Rume Sudan, Catimor, K7 and SL 28 (susceptible). Seedlings were individually scored for disease symptoms and mean grade of infection was computed. The mean grade data was then used to perform Analysis of Variance (ANOVA) using the random effects model. The results were used to determine the correlation between molecular polymorphism and diversity in virulence. The variety x isolate interaction effects although significant (p<0.05) did not conclusively reveal the existence of races because the isolate effect was not significant. The virulence tests revealed that variation was due to main effects of varieties. Rume Sudan was highly resistant with a mean grade of 4.75. Catimor with a mean grade of 7.66 showed medium resistance. K-7 showed medium resistance with a mean grade of 9.97. SL 28 was highly susceptible with a mean grade of 11.75. The growing regions had no influence on the genetic and virulence diversity since C. kahawae isolates from all regions were pathogenic on the tested coffee cultivars. All the isolates were significantly (p<0.05) more aggressive on coffee cultivar SL28, followed by K7 and Catimor in that order. Rume Sudan showed high resistance to all the tested isolates irrespective of the region. It is concluded that variation in Colletotrichumkahawae population is largely due to differences in aggressiveness of the isolates.Item Physiological and Agronomic Performance of Domesticated and Wild Cotton Germplasm from Selected Regions of Kenya(2017-05) Kiranga, Anthony N.; Njoka, Fredrick M.; Nderito, Charles W.making cooking oil, soup and seed cake for animal feed industry among other uses. Performance of wild cotton germplasm in Kenya has not been well studied and therefore there is need for understanding the correlation of traits influencing seed cotton productivity for effective improvement of the standard HART 89M. The study aimed at determining the correlation in performance between domesticated cotton HART 89M with wild cotton. Experimental Layout: Four wild cotton species and HART 89M were planted in three experimental blocks, each measuring 6 m by 30 m. There were three replications per experimental block, the distance between blocks was 2 m. The experimental blocks were then divided into 5 plots of 5 m by 5 m, with 1 m separating plots. The cotton seeds were planted in rows of 1 m by 0.5 m at depth of 2 cm. Methodology: Data on agronomic traits such as germination rate, flowering rate, height, number of fruiting branches, length of the longest fruiting branch, internodal length, number of nodes on the longest fruiting branch and yield per plant was collected from a sample of forty-five plants. One way Analysis of Variance (ANOVA) was used to determine the significant difference among the studied species and varieties at P = 5%. Results: There was a significant difference between the standard genotype (HART 89M) and studied wild genotypes with G. barbadense having highest height (203.37 cm), number of fruiting branches (66.93 cm), length of the longest fruiting branch (68.36 cm), number of nodes on the longest fruiting branch (5.38) and productivity (205.21 g) compared with other genotypes. G. kirkii had the longest intermodal length of 6.36 cm. Conclusion: On boll traits the highest significant difference with HART 89M was found with G. kirkii on boll weight (3.71 g), seed weight (2.30 g), and lint weight (1.41 g). Cotton breeding programs should consider traits such as plant height, number of fruiting branches, number of nodes on the longest fruiting branch, boll weight, seed weight and lint weight during selection as they were the major attributes of the seed cotton productivity. G. herbaceum and G. kirkii were recommended for seed production.Item Public perceptions towards genetically modified crops and foods in Kenya(2009) Anunda, H.; Njoka, Fredrick M.; Shauri, H.The broad objective of the study was to assess public perception towards Genetically Modified (GM) Crops and Foods in Kenya. The specific objectives were to find out the influence of background factors and Agro-ecological zones on the public perception towards GMCs and Foods in the country. A survey was carried out in Kenya covering all the 8 provinces between November 2007 and June 2008, targeting adult civilian population (aged 18+ years). The researchers set out to attain a sample size of 700 subjects so as to achieve a sampling error rate of +3.7%. Accordingly, four clusters comprising of general consumers, farmers, academicians, and resource persons were selected for the study. Efforts were made to ensure that the sample drawn was representative of the Kenyan population through Simple Random Sampling, Systematic Sampling, Convenient and Snowball Sampling as was appropriate. Data was collected using self administered questionnaires. Specifically, the survey instrument was designed to gather information on the participants’ background, ecological zones and perception towards GMCs and foods. Overall, well over one half (58%) of the respondents had positive perceptions towards GMCs and foods. Further, results of the study indicated that positive perception towards GMCs and foods was significantly related not only to the participant’s demographics but also to their Agroecological zones. Findings of the study suggest the need for a well designed and effective program to create awareness and educate the public about various issues relating to GMCs and foods. Various stakeholder such as the government, scientists, Non Governmental Organizations and the private sector need to communicate proactively with the public, especially women, elderly people etc, with complete and accurate information about GMCs and Foods.Item Screening for Water Deficit Tolerance, Relative Growth Analysis and Agrobacterium-Infectivity in Tropical Maize [Zea Mays L.] Inbred Lines in Nairobi, Kenya(2014-10) Sande, Olive F.; Njoka, Fredrick M.; Mgutu, Allan J.; Anami, Sylvester E.The gap between maize demand and regional supply is increasing as small-holder farmers grapple with many challenges, key among them drought. Research in identifying maize lines that are tolerant to water deficit and that are amenable to A. tumefaciens-mediated transformation is a step towards enhancing food security. The objectives of this study were, to assess the physiological response of tropical maize inbred lines to water deficit, to determine whether A. tumefaciens elicits host resistance when in contact with zygotic embryos and determine if YEP is an effective infection medium compared to MS medium in immature zygotic embryo infection. Tropical maize lines CML 395, CML 216, CML 144, TL 21, A 04, E 04 and T 04 and Agrobacterium strain EHA101 habouring pTF102 vector containing GUS reporter gene were used. Physiological response of tropical maize genotypes to drought stress was evaluated by measuring plant height, leaf length, leaf width and fresh weight. T 04 and CML 216 seedlings exhibited the fastest growth rates of 4.33 cm and 4.28 cm respectively between the 7th and 8th day post leaf four emergence while TL 21 and CML 395 seedlings had the lowest rates of 2.93 cm and 3.59 cm respectively under normal growth conditions. A 04 seedlings exhibited the highest differences in fresh weight between stressed and unstressed plants [56.13 gm] while CML 216 seedlings had the lowest [24.57 gm]. Upon salt stress, leaf discs of CML 216 seedlings, exhibited low chlorophyll a: b ratios of 0.84, 0.78, 0.74, 0.75 and 0.70 in 100 mM, 125 mM, 150 mM, 175 mM and 200 mM NaCl concentrations respectively, while leaf discs of CML 144 seedlings exhibited higher chlorophyll a: b ratios of 1.51, 1.19, 1.24, 1.26, 1.45 and 1.39 under the same concentrations. The use of YEP medium in contrast to MS medium led to an improvement in transient GUS expression observed in immature embryos and significant increase in transformation frequency. The transformation protocol using YEP infection media as used in this study should be optimized and used in transformation of tropical maize inbreds.Item Screening for Water Deficit Tolerance, Relative Growth Analysis and Agrobacterium-Infectivity in Tropical Maize [Zea Mays L.] Inbred Lines in Nairobi, Kenya(2014-10) Olive, Sande F.; Njoka, Fredrick M.; Mgutu, Allan J.; Anami, Sylvester E.The gap between maize demand and regional supply is increasing as small-holder farmers grapple with many challenges, key among them drought. Research in identifying maize lines that are tolerant to water deficit and that are amenable to A. tumefaciens-mediated transformation is a step towards enhancing food security. The objectives of this study were, to assess the physiological response of tropical maize inbred lines to water deficit, to determine whether A. tumefaciens elicits host resistance when in contact with zygotic embryos and determine if YEP is an effective infection medium compared to MS medium in immature zygotic embryo infection. Tropical maize lines CML 395, CML 216, CML 144, TL 21, A 04, E 04 and T 04 and Agrobacterium strain EHA101 habouring pTF102 vector containing GUS reporter gene were used. Physiological response of tropical maize genotypes to drought stress was evaluated by measuring plant height, leaf length, leaf width and fresh weight. T 04 and CML 216 seedlings exhibited the fastest growth rates of 4.33 cm and 4.28 cm respectively between the 7th and 8th day post leaf four emergence while TL 21 and CML 395 seedlings had the lowest rates of 2.93 cm and 3.59 cm respectively under normal growth conditions. A 04 seedlings exhibited the highest differences in fresh weight between stressed and unstressed plants [56.13 gm] while CML 216 seedlings had the lowest [24.57 gm]. Upon salt stress, leaf discs of CML 216 seedlings, exhibited low chlorophyll a: b ratios of 0.84, 0.78, 0.74, 0.75 and 0.70 in 100 mM, 125 mM, 150 mM, 175 mM and 200 mM NaCl concentrations respectively, while leaf discs of CML 144 seedlings exhibited higher chlorophyll a: b ratios of 1.51, 1.19, 1.24, 1.26, 1.45 and 1.39 under the same concentrations. The use of YEP medium in contrast to MS medium led to an improvement in transient GUS expression observed in immature embryos and significant increase in transformation frequency. The transformation protocol using YEP infection media as used in this study should be optimized and used in transformation of tropical maize inbreds.Item Screening for Water Deficit Tolerance, Relative Growth Analysis and Agrobacterium-Infectivity in Tropical Maize [Zea Mays L.] Inbred Lines in Nairobi, Kenya(2014-12) Olive, Sande F.; Njoka, Fredrick M.; Mgutu, Allan J; Anami, Sylvester E.The gap between maize demand and regional supply is increasing as small-holder farmers grapple with many challenges, key among them drought. Research in identifying maize lines that are tolerant to water deficit and that are amenable to A. tumefaciens-mediated transformation is a step towards enhancing food security. The objectives of this study were, to assess the physiological response of tropical maize inbred lines to water deficit, to determine whether A. tumefaciens elicits host resistance when in contact with zygotic embryos and determine if YEP is an effective infection medium compared to MS medium in immature zygotic embryo infection. Tropical maize lines CML 395, CML 216, CML 144, TL 21, A 04, E 04 and T 04 and Agrobacterium strain EHA101 habouring pTF102 vector containing GUS reporter gene were used. Physiological response of tropical maize genotypes to drought stress was evaluated by measuring plant height, leaf length, leaf width and fresh weight. T 04 and CML 216 seedlings exhibited the fastest growth rates of 4.33 cm and 4.28 cm respectively between the 7th and 8th day post leaf four emergence while TL 21 and CML 395 seedlings had the lowest rates of 2.93 cm and 3.59 cm respectively under normal growth conditions. A 04 seedlings exhibited the highest differences in fresh weight between stressed and unstressed plants [56.13 gm] while CML 216 seedlings had the lowest [24.57 gm]. Upon salt stress, leaf discs of CML 216 seedlings, exhibited low chlorophyll a: b ratios of 0.84, 0.78, 0.74, 0.75 and 0.70 in 100 mM, 125 mM, 150 mM, 175 mM and 200 mM NaCl concentrations respectively, while leaf discs of CML 144 seedlings exhibited higher chlorophyll a: b ratios of 1.51, 1.19, 1.24, 1.26, 1.45 and 1.39 under the same concentrations. The use of YEP medium in contrast to MS medium led to an improvement in transient GUS expression observed in immature embryos and significant increase in transformation frequency. The transformation protocol using YEP infection media as used in this study should be optimized and used in transformation of tropical maize inbreds.Item Staff Profile - Prof. Njoka Fredrick M.(University of Embu, 2015-07) Njoka, Fredrick M.