MST-Department of Agricultural Sciences and Technology

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    Arbuscular Mycorrhizal Fungi and Silicon Effects on Nutrient Uptake, Growth and Yield of Sorghum under Water Stress in Machakos County, Kenya
    (Kenyatta University, 2021) Gacheri, Kaaria Kallen; Catherine W. Muui; Joseph Onyango Gweyi
    Sorghum (Sorghum bicolour L. Moench) is an important cereal crop ranked second after maize as a food security in Kenya. However, its production is threatened by low soil fertility and moisture content. Many studies on arbuscular mycorrhizal fungi (AMF) have shown its importance in nutrient and water uptake, resulting in better yields of crops. In addition, silicon helps in plant resistance to both abiotic and biotic stresses. The study evaluated effects of AMF and silicon on nutrients uptake, growth and yield of two sorghum varieties under different water regimes. Two field experiments were carried out in Machakos County, Kenya. A Randomized Completely Block Design (RCBD) in a factorial arrangement was used to lay out the experiment. The factors tested included: Two levels of sorghum varieties (Seredo and Machakos local red), the other factor was water regimes in three levels (20, 40 and 60%) while the third level was silicon and Mychorriza (plus and minus). Sorghum varieties and leek were used as trap plants in a greenhouse experiment. Data collection was done on sorghum growth, yield and nutrient uptake, AMF colonization percentage and AMF diversity. Analysis of variance (ANOVA) was used to analyze data using R software and significant means se parated using Tukey’s test at 5% significance level. The results showed that Seredo variety had the highest shoot dry weight (107 g), longest roots (44.1 cm) and longest period to 50% flowering (76.4%) while Machakos local red had tallest plants (210.9 cm) and highest number of leaves (10.8). At 60% water regime, Si amendment and AMF inoculation enhanced sorghum growth better than other treatments. Seredo variety recorded the highest grain yield (4.4 tha-1). The variety also revealed various nutrient uptake as follows:- phosphorus (111.1 kg ha-1), nitrogen (34.7 kg ha-1), K (69.7 kg ha-1), calcium (3296 kg ha-1) and magnesium (172.1 kg ha-1) uptake. It has recorded the best AMF root colonization. Moreover, Seredo variety had the maximum harvest index of 0.39. At 40% water regime, Seredo variety amendment with Si and AMF produced the highest grain yields, nutrients uptake and AMF root colonization. A total of 4 AMF genera (Gigaspora, Scutellospora, Acuolospora and Glomus spp) from the family Gigasporaceae, Acaulosporacea and Glomeraceae were detected from both trap culture and experimental soil. The trap culture had the highest number of spore density 57.5 (leek), 32.8 (Seredo) and 23.5 (Machakos red local) compared to the experimental soil that had 15 spores per 100g of soil. Leek plants trapped more Glomus (23), Scutellospora (15.8) and Acaulospora (11.8) than both sorghum varieties but Seredo variety trapped most Gigaspora (15.3) per 100g of soil. This study demonstrated that Si amendment and AMF inoculants have potential of improving sorghum growth and yield under water stressed conditions as indicated by the high grain yield and nutrients uptake achieved at 40% water regime. Therefore, combined use of Silicon and AMF is recommended for improving sorghum productivity in water stress areas. Such strategies could enable food production in marginal areas characterized by low rainfall and high temperatures.
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    Assessed Line by Tester Analysis of Maize Inbreds for Northern Leaf Blight and Other Yield Components in Selected Counties, Kenya
    (Kenyatta University, 2021) Ndung’u, Ferista Wanjiku; Wilson M. Thagana; David K. Ndung’u
    Northern Leaf Blight (NLB) also known as Turcicum Leaf Blight (TLB) is a foliar disease of maize caused by Exserohilum turcicum. It is a great challenge in many maize production regions worldwide. It has a growing season characteristic of high humidity and moderate temperatures ranging from 17-270C. The disease can result to great yield losses in maize ranging at 40-70% in the case where there is disease presence 2-3 weeks after the crop silks. The main aim of this study was to assess the combining ability of the maize lines to NLB and other yield related traits, to determine the heterotic orientation of the lines and to establish the yield potential of the crosses across different environments. The lines were introductions and the study was aimed to determine the performance of the lines prior to further development. Forty nine lines used in the study were obtained from a segregating population in the F4 were crossed to two CIMMYT testers Tester A (CML312/CML442) and Tester B (CML395/CML444). The 98 crosses were planted in 3 mid-altitude agro-ecological zones of Kenya (Kakamega, Muranga and Embu). The heterotic orientation was determined for the lines and that differed across the 3 sites. The 3 sites were treated as independent environments due to genotype x environment interactions. Data was analyzed using REML, META-R and AGD-R tools. The results indicated significant GCA and SCA of some of the lines to NLB and different yield related traits including AD (days to anthesis) and SD (days to silking). The lines expressing significant GCA and SCA for NLB tolerance and high yield, the lines are recommended for further testing and development of NLB tolerant and high yielding maize hybrids in the mid-altitude agro-ecological zones of Kenya. The lines will recommended for use in breeding following further segregation hence could be used to develop hybrids that could be further subjected to trialing to obtain hybrids that are resistant to NLB, early maturing and high yielding. For the lines that could not be classified to their heterotic groups using Tester A and Tester B, these could be subjected to further tests with different testers in order to determine their heterotic groups and the knowledge could later be used in development of crosses.
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    Assessing the Suitability of Selected Areas in Kiambu, Kajiado and Machakos Counties for the Production of Capsicum (Capsicum Annuum L.)
    (Kenyatta University, 2021) Otieno, Michelle Awuor; Benjamin O. Danga; Harun Gitari
    Evaluation of land is a process by which land appropriateness is identified for its capabilities to grow a certain crop in any piece of land. This study aimed at assessing land in the peri-urban counties of Nairobi (Kiambu, Kajiado and Machakos) for growing capsicum (Capsicum annuum L.). Capsicum production in these counties has been doing well until 2014 when the production started to decline. The potential of land to produce capsicum is not known; farmers continue to grow capsicum without clear guidelines. It is for this reason that this study was carried out to determine areas best suited for capsicum production for improved production and to determine limitations that exist in crop production in these regions. To determine suitable areas for capsicum production in the three counties, Soil (pH, drainage, texture and electrical conductivity), climate (temperature and rainfall), and topography (slope and elevation) were the main criteria selected from the literature for the study. The AHP was used to determine the relevance of a criterion based on its cumulative weights as per the Saaty’s table. The cumulative weights were used to construct output maps using Quantum Geographic Information Software (QGIS). Crop suitability map was produced through overlaying of the different thematic maps and suitability levels were based on Food and Agriculture (FAO) land suitability classification. An extensive data set was utilized in the study, both primary and secondary data. The datasets were derived from climate data, soil data and satellite imagery themes. The study used a multi-criteria evaluation approach by applying the Analytic Hierarchy Process (AHP). These are procedures utilized in the GIS environment to evaluate the suitability of land for a particular use. These methods involved a selection of various criteria used for analysis and categorized according to their usefulness concerning capsicum growth conditions/requirements. Soil samples were collected and analysed for both major and minor nutrients (nitrogen, phosphorus, potassium, calcium, sulphur, magnesium, iron, manganese, boron, copper and zinc), then the data was used to generate a soil fertility map for the three counties. Soil nutrients differed significantly across the counties. Nitrogen and organic carbon were deficient in both Kajiado and Machakos counties while phosphorus was in adequate amounts in the soil but not sufficient enough to meet the requirements of the crop. The results showed that about 50% of land in Kiambu County, 8% in Kajiado County and 12% in Machakos County is suitable for capsicum production. The remaining areas were reported unsuitable for the production of the capsicum due to the presence of some limitations such as texture, soil pH, drainage and climate. A fertilizer program for growing capsicum was produced to help farmers in their planning schedules. In the program, urea, manure and triple super phosphate (TSP) were recommended at different rates to address the low nitrogen, organic carbon and phosphorus in the soils. To improve on the suitability and production of capsicum, there is a need to address the limitations experienced in the counties.
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    Assessment of Agronomic Performance and Haploid Induction Rate of Tropically Adapted Inducer Maize Lines
    (Kenyatta University, 2018) Nzamu, Janet Mwende
    Hybrid maize varieties are developed using inbred lines. Conventionally, inbred lines are developed by self-pollination, which takes 6-8 generations. The technology of doubled haploid (DH) is new and the most efficient in the development of inbred lines since complete homozygosity is achieved in 2 crop seasons. Haploid inducers have been refereed variedly as genetic stock which through crossing to a diploid plant, result in a mix of haploid and diploid kernels. These progeny segregates to diploid (2n) and haploid (n) kernels due to anomalous fertilization. The International Maize and Wheat Improvement Center (CIMMYT) and Hohenheim University have developed several tropicalized inducer Lines (TAILs) that have not been tested for haploid HIR under the Kenya maize growing environment. A study was therefore set up in collaboration with CIMMYT at the DH facility located at Kiboko in Makueni County to test seven TAILs (first generation TAILs 7, 8, 9, Hybrid 9×7 and 9×8 and second generation TAILs 008 and 009) for HIR in Kenya. The objective was to improve the efficiency of hybrid maize development using haploid inducers with good agronomic performance and highest haploid induction rate. A split plot arrangement was used in the experiment in which the inducers were the main plots while the female populations were the sub plots. Randomized complete block design (RCBD) was adopted with three replications. Three female populations (ligule less tester and two normal populations) were crossed with the seven TAILS. The F1 were germinated and the seedlings used to determine HIR of the Tails using their morphological plant characters. Pollen was harvested randomly from 10 plants of each haploid inducer line three days after pollen shed. TTC (2, 3, 5- triphenlytetrazolium chloride) solution was used as the staining technique of pollen at different times of day to determine pollen viability. Data collected was subjected to ANOVA using R- software version 3.2.3. Means of HIR and agronomic characters of the inducers were separated using the least significance difference (LSD) at 5% level of significance. The results showed that Tail 009 had the best plant and ear height, while Tail 7 had the best number of tassel braches and large tassel size. Pollen viability was high in the morning hours to noon and started to reduce in the afternoon hours. Despite this, pollen viability was above 90% in all the inducers, with TAIL 7 having the highest viability (98.45%) and TAIL 009 the lowest viability (92.77%). The ligule less tester and normal population 2 showed the highest HIR of 7.62-8.49% respectively; hence they can be used for the determination of HIR of target haploid inducer lines. Tail 8 and 9 had the highest HIR hence they can be used for haploid induction in target germ plasm. Plant height and HIR on the ligule less tester showed a positive correlation. The study was fundamental in identifying haploid inducer lines with high HIR for commercial development of homozygous lines and the results could lead to more efficient haploid induction in elite maize germplasm
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    Assessment of Germination Potential and Population Status of Melia Volkensii Gürke in Kitui County, Kenya
    (Kenyatta University, 2022) Njehu, Mukami Jane; Emily Wabuyele
    Melia volkensii Gürke is a native tree species that grows in the arid and semi-arid areas of East Africa. There has been overutilization of this tree which may lead to risk of rapid decrease in its community and genetic diversity. Additionally, planning and implementing planting programmes and conservation plans of M. volkensii have been hindered by insufficient knowledge on its seed storage behavior. This study sought to develop optimal protocols for seed germination and assess population status of Melia volkensii to enhance conservation and supply chain management in Kitui County. Melia volkensii fruits were collected from Tiva Forest and the germination experiment was carried out in KEFRI Kitui within nursery conditions. Seed germination experiments were arranged in a completely randomized design with three factors – extraction state, storage container and storage temperature. For extraction, seeds were divided into two lots – extracted seeds and unextracted seed (nut). Two types of storage containers were used namely sealed and unsealed. The storage temperatures were room temperature (30oC) and cold storage (-20oC). Germination tests were done before storage, and later after 2, 4 and 6 months in storage from each of the storage conditions. A hundred seeds and nuts each were sown for each experimental unit. The rate of seedling sprouting was recorded for a duration of 10 days as a percentage of seeds sown. Variation in germination percentages “was tested using two-way analysis of variance (ANOVA) at 95 % confidence interval and means separated using fisher’s protected least significant difference” in R and SAS statistical software. The highest percentage (89 %) was scored in nuts kept in unsealed containers at 30oC at 6 months and the lowest (14 %) in seeds stored in similar conditions for 2 months.The differences were significant. These results indicate that the germination rates of M. volkensii seeds increased with increase in period of storage. Additionally, plant population was determined in situ across seven transect lines measuring 1050 meters in length. Sampling was carried out in five plots measuring 50 x 50 m established at intervals of 200 meters. Transect 1 and 7 were laid in farmland while the transects between these two were laid in bushland. All tree species represented in each plot were counted. “Height and diameter at breast height (DBH) were measured for all M. volkensii trees within the plots. Melia volkensii seedlings and coppices were counted in 5 x 5 m nested plots within the larger plots. One-way analysis of variance (ANOVA) at 95 % confidence interval was used to test for variance in parameters measured and means separated using Tukey’s HSD. There were significant differences in height and DBH” means of M. volkensii among transects. Transect 2 had the lowest mean height and DBH while the tallest trees were in transects 1, 3, 4, and 6. Transect 1 had highest mean DBH. Means of seedlings were not significantly different among transects. Coppicing was significantly highest in transects 1 and 4. Moreover, relative abundance, species richness and diversity of plant species observed were analyzed “using Simpson’s index of biodiversity and Shannon-Wiener species diversity index. Melia volkensii was the most frequently occurring species with 12.2% (n=67) followed by Acacia tortilis10.0 % (n=55). Calotropis strophela, Commiphora capensis, Maerua crassifolia were the least represented relative abundance of 0.18 %. Values of indices used varied among transects and did not follow the location of transect implying that diversity was not determined by land disturbance. In conclusion, nuts stored unsealed at room temperature have the highest longevity. Based on diversity and relative abundance of M. volkensii and associated tree species in the study area, tree exploitation in Kasaala Location does not cause
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    Assessment of levels of natural radioactivity in surface soils around titanium mines in Kenya
    (2011-11-07) Masore, Kefa Osoro
    All human beings are exposed to radiation from naturally occurring radionuclides in soil and other environmental materials. Some of these exposures are not amenable to control and they are usually referred to as background radiation. Some work activities such as conventional mining inadvertently produce large quantities of naturally occurring radionuclides, which can result in additional and/or elevated levels of radiation exposure of people in the areas around the mining sites. Such exposures - induced or enhanced by human activities - are subject to control by regulatory authorities. In some instances there may be contributions from the two types of exposures and they must be separated before applying regulatory control. In this study, natural radioactivity levels in surface soils around the proposed titanium mines in Kwale district were determined from measurements of 78 samples of surface soils randomly sampled from two villages within the proposed mining area by using a hyper pure germanium (HpGe) gamma-ray spectrometer. The values of radioactivity concentrations in the soils and the likely radiation doses from contact with these soils were determined and are reported in this thesis. The radiological implication of these levels is discussed with regards to the impending mining operations in the area. The ranges and mean of radioactivity concentrations (Bgkg-l) obtained are. 8.4±0.4-43.6±1.5 (_27.6±1.7) for 232Th; 7.4±0.6-40.6±1.4 .(20.9±1.5) for 226Ra and 31.9±1.3-114.1±1.4 (69.5±3.2) for 40K, respectively. The likely absorbed dose rates in air above these soils were calculated from these radioactivity concentrations and found to be 8.5±0.5-36.9±1.1 nGyh-1 with a mean of 25.2±1.4 nGyh-1. The corresponding effective dose rates are 21.0±1.2-90.8±2.6 mSvy--1 with a mean of 62.0±3.5 uSvy--1, which are lower than the global average of 0.46 mSvy 1 and therefore of little radiological risk to the environment of the study subject.
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    Assessment of Optimal Interactions of Water Levels and Nitrogen Fertilizer Rates for Greenhouse Lettuce Performance in Kalro Kabete, Nairobi
    (Kenyatta University, 2021) Kaburu, Fabian; Benjamin O. Danga; Fuchaka Waswa
    Achieving food security globally has been curtailed by several factors including water scarcity, nutrient mining, limiting land resource and climate change. Nevertheless, irrigation under greenhouse farming has been confirmed to have the potential to solve water scarcity and crop nutrition problems thus increasing food production in controlled environments. This study aimed at assessing the optimal interactions of water levels and nitrogen fertilizer rates for greenhouse lettuce performance in the Kenya Agricultural and Livestock Research Organisation (KALRO) at Kabete, Nairobi. The specific objectives were to assess the optimal interactions of nitrogen fertilizer rates and water levels for highest performance of greenhouse lettuce, to determine the effect of N fertilizer dosage on water use efficiency in greenhouse lettuce yield and to investigate the effect of water levels and N-rates on water productivity index for the greenhouse lettuce yield in urban Nairobi. A survey was conducted using questionnaires to establish the amounts of water and N fertilizer rates green-house farmers within the study area were using for their vegetables production. The experiment conducted at the KALRO Kabete entailed use of a split plot randomized complete block design for two seasons between October 2017 and February 2018. The treatments included 3 levels of irrigation (W1-100% W2-70% (and W3-40% to FC) in main plots while 4 nitrogen levels (0, 65, 105, and 145 kgN/ha) were assigned to the subplots, resulting in 12 treatment combinations which were replicated three times. Soil moisture was determined using a neutron probe while water use efficiency (WUE) was calculated by dividing lettuce yield by AETc. A digital calorimeter was used to determine the leaf chlorophyll concentration. All data were subjected to analysis of variance (ANOVA) using Genstat version 15. Separation of means was performed using Turkey’s test at 95% level of confidence. Findings showed significant variations existed due to interaction effect of nitrogen fertilizer rates and water levels on lettuce height and number of leaves at season two. Variations were however insignificant during season one. A significant effect was observed due to the interaction of nitrogen fertilizer rates and water levels on lettuce diameter at season one and season two with 0.004* and 0.008* respectively. There was significant effect (0.005* and 0.003* for S1 and S2) observed due to interaction of nitrogen fertilizer rates and water levels on percentage chlorophyll during both seasons. However, no significant variation was observed due to interaction effect of nitrogen fertilizer rates and water levels on fresh (0.966 and 0.212 for S1 and S2) and dry weight (0.301 and 0.130 for S1 and S2) of lettuce during season one and season two. Findings also showed no significant variation (0.088 and 0.404 for S1 and S2) due to the effect of nitrogen fertilizer application rates on water use efficiency during season one and season two. Findings indicated that water use efficiency was highest at treatment W3N1 with 230.06 kg/Ha/mm and 209.68kg/Ha/mm during season one and season two respectively. Additionally, water productivity index was significant during season one and insignificant during season two with findings indicating that treatment W3N1 was the most water productive treatment during both seasons with 66.29 kg/m3 and 50.46kg/m3 during season one and season two respectively. As such, farmers growing lettuce crop under greenhouse technology should use water applied at 40% field capacity that is 12 minutes and fertilizer rate of 65kg/ha since it showed efficient use of water and high productivity.
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    Biocontrol of Late Blight Phytophthora Infestans on Potato Using Selected Fungal Antagonists and Plant Extracts in Kiambu and Nyandarua Counties, Kenya
    (Kenyatta University, 2021) Agong, Steve Ochieng; Maina mwangi; Ruth Kahuthia
    Potato late blight (Phytophthora infestans (Mont.) de Bary) is a major threat to potato production instigating overreliance on synthetic fungicides. Synthetics however, cause human health complications, environmental pollution and resistance development by late blight; this can be substituted with safer biological control options. The study objective was to enhance potato production through sustainable management of potato late blight. In May 2018, a baseline survey was carried out in Nyandarua County to assess the socio-demographic factors, potato production and crop management practices that impact on prevalence of potato late blight. Overall, 105 small scale farmers were interviewed using semi-structured questionnaires. Survey data was analyzed using SPSS v.20. Fungi were isolated from potato rhizosphere using serial dilution method and subsequently screened in vitro via dual culture technique. Crude extracts were prepared from bioactive plants using maceration technique then evaluated in vitro via poison food technique. Data, on P. infestans mycelial growth inhibition and suppression by fungal isolates and crude extracts, respectively, was analyzed using SAS v.9.2 at P≤0.05. Azadirachta indica extract and Trichoderma hamatum isolate caused significant suppressive and inhibitory effects in vitro of up to 59.1 and 50.2%, respectively. Trichoderma harzianum, T. afroharzianum, T. asperellum, A. indica, Pistacia lentiscus and Tithonia diversifolia significantly (P<0.05) suppressed pathogen growth in vitro thus were considered for further screening in the field. Isolates were tested on potato cultivars, Shangi and Tigoni, compared to water and Master® as controls. The trial was an RCBD for three cropping seasons, including two long rains (May to August 2018 and April to July 2019) and one short rain (December 2018 to March 2019). Data on disease incidence, severity and yield was analyzed using SAS v.9.2 at P≤0.05. Findings showed male dominance in potato production at 62%, 43.8% of respondents attained primary education, 74.3% used saved seeds and 65.8% used a single fungicide class. Under field evaluation, T. hamatum significantly (P<0.001) reduced disease incidence and severity on Shangi and Tigoni by up to 92.7±4.3 and 54±6.1%, respectively (May to August 2018). Azadirachta indica and T. hamatum supressed disease up to 89.1±2.3 and 65.2±4.5%, respectively, on Tigoni variety. Fungal antagonists generally caused significantly (P≤0.001) higher yields compared to plant extracts. During May to August 2018 and April to July 2019, T. harzianum and T. diversifolia yielded up to 3.65±1.2t/ha and 5.75±1.3t/ha, respectively. Education is considered important as knowledge level influences decision making and adoption of technologies and practices. Use of farm saved seeds is a potential source of inoculum and use of single fungicide class could lead to resistance development. Therefore, enhancing farmers‟ knowledge and promoting good agricultural practices that include IPM can improve management of potato late blight thus enhancing productivity. These results demonstrate existence of biologically active microorganisms and crude extracts from plants in the local environment that can be exploited towards developing affordable and safer management products for use against P. infestans.
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    Biology and Morphometric Characterization of Swallowtail Butterfly, Papilio Desmondi Teita and Papilio Nireus on Wild Citrus in Taita Taveta County, Kenya
    (Kenyatta University, 2023-10) Genga, Cramswel Oliver; Namikoye Everlyne Samita; Ruth Kahuthia-Gathu; Esther N. Kioko
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    Buffel (Cenchrus Ciliaris) and Sudan (Sorghum Sudanense) Grasses’ Growth, Yield and Quality Responses to Nitrogen Application in Mandera County, Kenya
    (Kenyatta University, 2023) Mohamed, Aden; Harun Gitari; Mwende Ngie
    Most arid and semiarid areas are bare and greatly infested with intrusive wild species. Buffel grass (Cenchrus ciliaris L.) and Sudan grass (Sorghum sudanense Piper.) are the supreme drought-tolerant grasses that are commonly grown in dry regions. Besides water, nitrogen (N) is a vital element limiting the growth, yield, and herbage quality of such grasses since it has key roles in physiological and biochemical functions in plants. Hence, this study aimed to assess the performance of Buffel and Sudan grasses under nitrogen fertilization in Mandera County. This study comprised a field trial laid as a split-plot in a randomized complete block design with grasses being assigned to the main plots, whereas N rates (0, 35, 70, 105, and 140 kg N ha-1) occupied the subplots. Data collection was carried out on growth parameters (plant height, leaf length, number of leaves per plant, leaf width, stem girth, and tiller number), yield parameters (shoot weight, root weight, and aboveground biomass yield DBY), and quality attributes (acid detergent fiber ADF, crude protein CP, and neutral detergent fiber NDF). Across the seasons, plant height progressively increased with increasing N rates up to a maximum of 141 and 246 cm for Buffel grass and Sudan grass, respectively, which were associated with a 105 kg N ha−1 rate. Nonetheless, there was no noteworthy enhancement in plant height (142 and 246 cm) with an additional upsurge in N fertilizer rate to 140 kg N ha−1 relative to the one of 105 kg N ha−1. Regarding the leaf length, Sudan grass had longer and wider leaves at all treatment levels than the Buffel grass. Plant height, leaf length, width, and the number of leaves per plant increased with increasing N level up to the rate of 140 kg N ha-1, though this was not statistically different from the rate of 105 kg N ha−1, for both kinds of grasses. The results revealed that Sudan grass contained higher crude protein than Buffel grass at all levels of treatments (10.33 and 8.80% at the rate of 105 kg N ha−1 respectively). More so, crude protein content was found to be higher in plots where N application was made than in the control plots. There were great associations between the dependent variables (DBY, ADF, NDF, and CP) and independent variables (plant height, leaf length, No. of leaves, leaf width, stem girth, and No. of tillers), with the coefficient of regression ranging from 0.56 to 0.96 for Buffel grass and 0.59 to 0.96 for Sudan grass. Findings from this study indicate that for optimal growth, yield, and nutrient content benefits, Buffel and Sudan grasses ought to be grown using nitrogen fertilizer at 105 kg N ha−1 rate. The study recommends the use of nitrogen fertilizer at the right time in the growth cycle of Buffel and Sudan grasses.
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    Characterization and Fungicide Sensitivity of Tomato Isolates of Alternaria Solani Sorauer in Kajiado, Kiambu and Kirinyaga Counties, Kenya
    (Kenyatta University, 2022) Nuwamanya, Andrew; Maina Mwangi; Steven Runo
    Early blight (EB) caused by Alternaria solani is ranked as one of the most important tomato diseases in Kenya and farmers predominantly rely on synthetic fungicides to control it. However, there have been reports about the declining efficacy of some fungicides against EB control. This study was carried out to (i) determine the occurrence, importance and current management practices for tomato EB in Kirinyaga, Kajiado and Kiambu counties, Kenya; (ii) characterize Alternaria solani tomato isolates from the selected counties by morphological features and sensitivity to two commonly used fungicide groups and (iii) determine occurrence and spatial distribution of resistance-associated mutations in A. solani isolates from the three counties. A baseline survey was carried out in 175 tomato fields in Kirinyaga (n=58), Kajiado (77) and Kiambu (40) counties, data was collected using semi-structured questionnaires and field observation. Tomato shoots showing typical EB symptoms were collected from surveyed fields (one per field) and carried to Kenyatta University Pathology Laboratory, where a total of 96 A. solani isolates were isolated. Results indicate that EB was highly prevalent (75-91%) in all regions and all farmers were controlling it by fungicide application. A total of 40 fungicide products, representing 20 active compounds, with varying resistance risk levels, were in use against EB. Most farmers (83%) were applying the fungicides at higher than the recommended doses. Most farmers (81%) reported declines in effectiveness of fungicides, especially strobilurins and triazoles. The Alternaria solani isolates were characterized based on cultural features, conidial morphology and sensitivity to two fungicides; azoxystrobin (a strobilurin) and difenoconazole (a triazole) in vitro by poisoned food technique. One way analysis of variance revealed that colony and conidial parameters of isolates did not differ significantly (at α=0.05) across the study counties. Isolates were considered resistant to the fungicide whenever their % Mycelial Growth Inhibition (%MGI) at manufacturer’s recommended dosage was below 50% and sensitive when above 50%. While all isolates were susceptible to Difenoconazole, majority of them (64%) were resistant to Azoxystrobin. Locations significantly differed in regard to sensitivity of isolates to fungicides with Kajiado and Kirinyaga isolates being least sensitive to Azoxystrobin and Difenoconazole, respectively. To determine the genetic basis of Azoxystrobin resistance, the cytochrome b gene (in all isolates) was PCR amplified, sequenced and analyzed for resistance-associated mutations at amino acid positions 129, 137 and 143. The F129L mutation was present in all Azoxystrobin resistant isolates plus 10 susceptible ones with MGI values close to the 50% threshold. Kajiado county had the highest percentage of mutated isolates (96.8%), followed by Kirinyaga (70%) and lastly Kiambu (40%). These findings indicate that Kenya’s A. solani populations have developed resistance to some fungicides by mutation. The study recommends that anti-fungicide resistance strategies should be applied, for more effective management of tomato early blight.
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    Characterization and Fungicide Sensitivity of Tomato Isolates of Alternaria Solani Sorauer in Kajiado, Kiambu and Kirinyaga Counties, Kenya
    (Kenyatta University, 2022) Nuwamanya, Andrew; Maina Mwangi; Steven Runo
    Early blight (EB) caused by Alternaria solani is ranked as one of the most important tomato diseases in Kenya and farmers predominantly rely on synthetic fungicides to control it. However, there have been reports about the declining efficacy of some fungicides against EB control. This study was carried out to (i) determine the occurrence, importance and current management practices for tomato EB in Kirinyaga, Kajiado and Kiambu counties, Kenya; (ii) characterize Alternaria solani tomato isolates from the selected counties by morphological features and sensitivity to two commonly used fungicide groups and (iii) determine occurrence and spatial distribution of resistance-associated mutations in A. solani isolates from the three counties. A baseline survey was carried out in 175 tomato fields in Kirinyaga (n=58), Kajiado (77) and Kiambu (40) counties, data was collected using semi-structured questionnaires and field observation. Tomato shoots showing typical EB symptoms were collected from surveyed fields (one per field) and carried to Kenyatta University Pathology Laboratory, where a total of 96 A. solani isolates were isolated. Results indicate that EB was highly prevalent (75-91%) in all regions and all farmers were controlling it by fungicide application. A total of 40 fungicide products, representing 20 active compounds, with varying resistance risk levels, were in use against EB. Most farmers (83%) were applying the fungicides at higher than the recommended doses. Most farmers (81%) reported declines in effectiveness of fungicides, especially strobilurins and triazoles. The Alternaria solani isolates were characterized based on cultural features, conidial morphology and sensitivity to two fungicides; azoxystrobin (a strobilurin) and difenoconazole (a triazole) in vitro by poisoned food technique. One way analysis of variance revealed that colony and conidial parameters of isolates did not differ significantly (at α=0.05) across the study counties. Isolates were considered resistant to the fungicide whenever their % Mycelial Growth Inhibition (%MGI) at manufacturer’s recommended dosage was below 50% and sensitive when above 50%. While all isolates were susceptible to Difenoconazole, majority of them (64%) were resistant to Azoxystrobin. Locations significantly differed in regard to sensitivity of isolates to fungicides with Kajiado and Kirinyaga isolates being least sensitive to Azoxystrobin and Difenoconazole, respectively. To determine the genetic basis of Azoxystrobin resistance, the cytochrome b gene (in all isolates) was PCR amplified, sequenced and analyzed for resistance-associated mutations at amino acid positions 129, 137 and 143. The F129L mutation was present in all Azoxystrobin resistant isolates plus 10 susceptible ones with MGI values close to the 50% threshold. Kajiado county had the highest percentage of mutated isolates (96.8%), followed by Kirinyaga (70%) and lastly Kiambu (40%). These findings indicate that Kenya’s A. solani populations have developed resistance to some fungicides by mutation. The study recommends that anti-fungicide resistance strategies should be applied, for more effective management of tomato early blight.
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    Characterization of Virus-Free Sweet Potato (Ipomea Hatata (L) Lam) Landraces Using Morphological and SSR Markers in East Kamagak Location-Homabay County
    (Kenyatta University, 2014) onyango, Rosally Anyango
    Sweet potato is one of the most important crops for food security and income generation in Kenya. The crop is increasing in importance as adverse climate changes limit crop production in many areas. Understanding the genetic diversity of germplasm of crop species is ofimportance for its rational management and use. Identification of the sweet potato landraces is paramount in addressing food security not only in the study region but elsewhere in the country. Morphological characterization of the accessions facilitates the identification of duplicates and unique traits which is important in the future improvement of the crop having the desired characteristics. The study aimed at identifying sweet potato landraces that have high quality and high consumer acceptance in the area in East Kamagak location of Rachuonyo District, Homabay County .The experiment started with survey and germplasm collection aided by use of questionnaire. The collected germplasm was virus indexed using visual scoring, serological and molecular detection. Six sweet potato landraces from East Kamagak along with six released varieties from Kenya Agricultural Research Institute Njoro were used for the study. The accessions were planted using Randomized Complete Block Design. Planting was done in two sites (Sino and Kachieng). Eighteen qualitative (ground cover, leaf shape, tuber colour.) and Eight quantitative characters (leaf length, vine inter-node length,vineweight, yield of tuber.) were scored one month after planting upto harvesting using the sweet potato descriptors oflnternational Potato Centre (CIP). Harvesting was done at 6 months after planting and tubers dried at 60°C to deterrn ine the dry matter content.The accessions exhibited high morphological diversity in aerial and rootcharacteristics. Analysis of variance showed that out of 24 characters evaluated for morphological characterization, 17 characters were significantly different at p
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    Correlation between Maize Lethal Necrosis Disease and Mycotoxin in Maize in Bomet, Narok and Nakuru Counties, Kenya.
    (Kenyatta University, 2021) Mwasame, Evans Natembeya; Maina mwangi; Catherene Taracha
    Maize Lethal Necrosis Disease (MLND) is believed to increase concomitant toxic fungal infections in maize. The goal of this study was to discover a link between MLND and fungal infections. During the 2018/2019 maize growing seasons, a Randomized Complete Block Design experiment with three replicates was set up in farmer's fields in three experimental sites in Bomet, Narok, and Nakuru Counties. Six hybrid maize varieties classified as resistant (KATEH16-02 and DK777), tolerant (WE5135 and WE5140), and susceptible (DUMA 43 and PH30G-20) to MLND were used. A total of 54 maize grain samples were collected. Fungal colonies were isolated on Potato Dextrose Agar medium and identified using morphological and microscopic techniques. ELISA test was used to quantify aflatoxins. The samples yielded 4561 fungal isolates, with Fusarium being the most predominant genus (79.75%), followed by Penicillium (16.03%) and Aspergillus (1.933%). A positive significant correlation between the MLND bioassay score, Penicilium and Aspergillus infection was achieved, (r = 0.429, p =0.001) and (r = 0.275, P =0.5) respectively. Aflatoxin concentration levels of between 0.3 and 2.8 μg/kg were detected in 38.89 % of the samples. Aflatoxin and MLND were significantly correlated (p =0.001, r2=0.547). Although this study was only able to show Aflatoxins, there is a strong likelihood of other mycotoxins occurring in maize grains in higher proportions. Therefore the public should be made aware of the mycotoxin risks associated with consumption of MLND infected maize.
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    Detection and Stability Assessment of Maize Chlorotic Mottle Virus in Maize Seeds in Kenya
    (Kenyatta University, 2023-10) Shango, Peter; Maina Mwangi; Shem Nchore
    Viral diseases, particularly Maize chlorotic mottle virus (MCMV) co-infecting with potyviruses causes Maize lethal necrotic disease (MLND), which is a major hurdle in maize production and a threat to food security in Africa. Maize lethal necrotic disease, spread by thrips, threatens Sub-Saharan Africa's maize yield and trade. In Kenya, where maize is crucial, controlling MLND has gained importance. Kenya Plant Health Inspectorate Services (KEPHIS) tests seeds to prevent virus-causing MLND, safeguarding the market and reducing losses for farmers and seed companies due to MCMV contamination. This research aimed at finding ways through which diseased seed lots could be saved by either inactivating the MCMV thermally or quarantining the seed for a particular duration during which MCMV could inactivate. Forty samples each comprising 400 seeds of infected seed lots were used during the experiments and subjected to different treatments. Thesc included different temperatures, storage time, and assessment of germination capacities after the exposure to different temperatures and times of storage. Extraction of Ribose nucleic acid (RNA) from 400 maize seedlings which were planted per each sample was carried out using the Cetyltrimethyl Ammonium Bromide (CTAB) method and the three testing methods Enzyme-Linked Immunosorbent Assay (ELISA), Loop-mediated isothermal amplification (LAMP), and Quantitative Polymerase chain reaction (q-PCR) were feasibly analyzed for their sensitivity as well as achieving other objectives. Analysis of Variance (ANOVA) was done by use of SAS. Results showed that MCMV Joad in maize seeds significantly reduced with storage (p=0.001). An increase in temperature to 40°C led to a significant decrease in MCMYV load but with a corresponding reduction in the viability of the seeds. The results from Loop-mediated isothermal amplification (LAMP) showed the best sensitivity in MCMYV detection up to dilution factor of 10°%, followed by real-time PCR which was sensitive up to dilution factor 10* and, lastly, the ELISA which was sensitive up to 10% In conclusion, the study demonstrates that MCMYV infected maize seeds can be stored for up to three years without a significant loss in seed viability. However, it is imperativeto avoid high temperatures, such as 40°C, during storage, as they can negatively impact seed quality. This information is crucial for policy makers in developing effective disease management strategies. Seed merchants can use this knowledge to ensure seed quality and avoid cconomic losses, while farmers can benefit from understanding the appropriate storage conditions for MCMYV infected seeds to manage the virus effectively while preserving seed viability. Additionally, the routine use of Loop-mediated isothermal amplification (LAMP) and real-time PCR techniques for MCMV detection is recommended.
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    Determining Pollinators, Floral Calendar and the Effect of Pollination Deficit of Avocado Persea Americana Mill in Kandara, Murang’a County, Kenya
    (Kenyatta University, 2019-11) Mulwa, Joseph Mutunga
    Avocado Persea americana Mill is an important fruit in Kenya. It is a source of vitamins, oil and income to farmers. However, its optimal production is dependent on insect pollinators. This study was undertaken to determine diversity and abundance of insects visiting avocado flowers, their diurnal visitation counts, the crop floral calendar and the effect of pollination deficit of avocado at Kandara, Murang’a County. The study was carried out in farmers’ fields in upper midland 2 agro ecological zone, for three cropping seasons, from August 2015 to March 2017. A total of 60 trees were randomly selected from 12 farms for the study with a minimum distance of 10 m and 200 m between trees and between farms, respectively. Treatments included unlimited access and no access of flowers by pollinators. On each tree, two randomly selected terminal branches with inflorescences of the same age and size were identified, where one was bagged using nylon mosquito nets to deny access by pollinators while the other was left open for unlimited access by pollinators. As soon as flowers wilted, the nets were removed, and fruits on the tagged terminal branches counted. Data collected included identity of the pollinator, number of individuals observed pollinating per species, time of the day, the time (seconds) taken by the pollinator on the flower per visit, the percentage flushing, percentage flower buds, percentage flowering and percentage fruiting. Number of male and female flowers was recorded from 0900 h to 1700 h. Fruit counts were done monthly. At maturity, fruits were harvested and their weight, polar diameter, equatorial diameter, seed weight, ovary polar and equatorial diameters were determined in the laboratory. Pollination deficit data were analyzed using Student’s t-test. Findings showed that honey bees Apis mellifera were the major flower visitors followed by blow flies Chrysomya putoria. Others included hoverflies Eristalis tenax, wasps Polistes sp., butterflies Colias electo, ants Iridomyrmex reburrus and beetles Drypta ruficollis. Opening and maturity of female and male phase flowers overlapped between 1200 h to 1659 h, with the peak overlap from 1300 h to 1359 h. Fruit set was significantly (P <0.001) higher in flowers where terminal branches were allowed unlimited access to pollinators (19.85±2.00) compared to those denied access (9.38±1.55). Further, a more than two folds increase in final fruit yield was recorded in terminal branches where flowers were exposed to unlimited access (0.46±0.08) by pollinators compared with those denied pollinator access (0.17±0.05). Based on the yield differences, a 64.5% pollination deficit was recorded for avocado. Laboratory results showed existence of significant statistical differences in seed weight (P=0.001) with those from terminal branches exposed to unlimited access having 15.41 ±1.75g compared with those denied access (7.13±1.07g). The differences also existed for ovary equatorial diameter (P=0.001) and fruit equatorial diameter (P=0.035). This study thus confirmed that pollination plays a significant role in avocado production. Farmers are advised to adopt appropriate pollination management plans for their avocado orchards such as provision of honey bee colonies and ensuring presence of diverse community of pollinators, which will enhance pollination provision by honey bees.
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    Economic avaluation of Integrated pest management technology for control of mango fruit flies in Embu County, Kenya
    (2014) Kibira, Mary Njeri
    Mango is the third most important fruit in Kenya in terms of area and total production. Nutritionally, mango fruit is important for vitamins and mineral provision in the daily diet of Kenyans. As an export crop, mango earns the country foreign exchange, acts as source of food and household income especially for resource poor farmers, contributing to poverty alleviation and achievement of Millennium Development Goal number one. However, mango production and marketing is constrained by several factors, among which pests and disease infestation is major. Among the pests, mango fruit fly present a real challenge to producers and exporters due to losses incurred at the farm level and infested mango rejections at export points. To reduce losses, cost of production and increase the profit at producer level, International Centre of Insect Physiology and Ecology (icipe) developed and implemented an Integrated Pest Management fruit fly control package (IPMFFCP) in Embu County, Kenya. The impact of this intervention, however, had not been evaluated. This study therefore evaluated the impact of this intervention on magnitude of mango rejection due to fruit fly damage, insecticide expenditure and net income from mango production. The study also established households’ perception of the effect of the intervention on human health. The study used survey research design in which a structured questionnaire was administered to 257 randomly selected IPMFFCP participants and non participants from the intervention and control areas. Ordinary Least Square (OLS) regression analysis and Difference-in-difference (DD) method were used to assess the impact of the IPMFFCP on magnitude of mango rejection and insecticide expenditure. Two Stage Least Square (2SLS) analysis and DD were used to evaluate the impact of IPMFFCP on net income from mango production. Descriptive statistics were used to assess the household perception of the effect of IPMFFCP on health. The results indicated that on average IPMFFCP participants had approximately 54.5 percent reduction in magnitude of mango rejection than the non participants. The participants spent approximately 46.3 percent less on insecticide per acre than the non participants and on average received approximately 22.4 percent more net income than the non participants. Results also showed that 78 percent of households perceived the intervention improved human health. The results imply that IPMFFCP participants are better off in terms of magnitude of mango rejection and insecticide expenditure reduction and net income from mango production increment. The study recommends expansion of IPMFFCP intervention to the entire mango growing area in Embu County to improve the farmers’ livelihood through the increased profitability.
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    Effect of Conservation Agriculture on Water Retention, Soil Properties and Maize Yields in Semi-Arid Kajiado County, Kenya
    (Kenyatta University, 2020) Ritei, Leonard Leakey
    Food insecurity and hunger are global challenges attributed to poor crop harvests, land degradation, low soil moisture and declining soil fertility. Low maize yields and household food insecurity in Kajiado, Kenya could be alleviated by use of sustainable agricultural practices such as conservation agriculture (CA), integrated soil fertility management (ISFM) and increased water use efficiency. This study was carried out in Kajiado during the long rainy season of March-July, 2016 to (i) determine the effects of conservation tillage on maize growth and yields (ii) determine the effects of conservation tillage on soil physical properties (soil moisture retention and soil structure) and (iii) determine the effect of conservation tillage on soil chemical properties (Soil Carbon, soil pH, soil N, P, and K). The treatments were laid out in a RCBD with three replications. The treatments included: 1. Conventional tillage with residue removal (Control). 2. Conventional tillage with residue retention (3 ton/ha). 3. Conventional tillage with residue retention (5 ton/ha incorporation). 4. Reduced tillage – (one plough with 3 ton/ha stover incorporation). 5. Reduced tillage – (one plough with 5 ton/ha stover incorporation). 6. No-tillage practice – (no prior tillage, 3 ton/ha stover residue chopped, surface applied). 7. No-tillage practice – (no prior tillage, 5 ton/ha stover residue chopped, surface applied). Analysis was done using SAS version 8. Results from the study show significant effects (p<0.05 and p<0.01) of CA on dry matter maize yields and water retention. The volumetric moisture content at 0-60 cm soil depth was highest in NT5 treatment, followed by NT-3 > RT-5 > CT-5>CT-3 > RT-3 and CTC (Control). At 0-20 cm depth, NT-5 had the highest volumetric soil moisture content of 0.299m3m-3 which was significantly higher than the other treatments. NT-5 increased soil moisture by 9.7%, NT3 by 9%, RT5 by 5.4%, while RT-3 by only 3.8%. After wet sieving, treatments, RT-5, NT-3 and NT-5 significantly increased the 2-1 mm soil aggregate size, thus indicating improvement in aggregate stability of the soils. Up to RT-3 does not degrade the soil structure because there was no significant reduction of the fraction less than 0.5mm. NT-5 significantly gave the highest stover yields of 5334kg/Ha and grain yields of 3228.2kg/ha which was 37.3% increase from the control. CT3 had the highest plant height at (12.5cm) 2 weeks after planting (2WAP). However, NT5 had the highest significant effect (P=0.01) on plant height 4WAP, 6WAP and 8WAP at 58.2 cm, 122.8 cm and 140.2 cm respectively. No significant effects (P<0.01 and P<0.05) were recorded in pH before and after the experiment. However, soil organic carbon (SOC) recorded significant improvements across all the treatments with NT-5 being the highest followed by RT-5 > RT-3 > NT- 3> CT-5 > CT-3 respectively in that order. The treatments had significant effects on soil mineral N (NH4+ and NO3-) and total N. On the other hand, the treatments also had significant effects on available P, Na+, and K+. Therefore, the results confirm that CA is very effective in enhancing crop yields and improving soil physical and chemical properties.
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    Effect of Gibberellic Acid 4 and 7 and 6-Benzyl Adenine on Growth, Yield and Quality of Sugarcane in Kakamega County, Kenya
    (Kenyatta University, 2020) Achola, Andrew Adodi
    Declining sugarcane productivity in Kenya has attracted a plethora of interventions such as optimal fertilizer regimes, improved seedcane quality and use of plant growth regulators (PGRs). Although application of PGRs in leading sugarcane producing countries like China and India has registered success, sugarcane farmers in Kenya are yet to exploit this technology. Globalization and liberation of world sugar industry now subjects the local millers and farmers to stiff competition. The local sugar millers have responded by seeking to adopt payment model based on yield and sucrose content. To address this problem, a study was conducted to determine the effect of different levels of gibberellic acid 4 and 7 and 6-benzyl adenine on growth, yield and sucrose content of five selected sugarcane varieties (CO 421, KEN 83-737, D8484, CO 945 and EAK 73- 335). The study was carried out at the Butali Sugar Company Research and Demonstration farm in Chegulo, Kakamega County-Kenya. The trial was laid out in a Randomized Complete Block Design in 5 by 5 factorial arrangement. The treatments consisted of gibberellic acid 4 and 7 and 6-benzyl adenine at 0 1, 2, 3 and 4 litres per hectare and the five sugarcane varieties. All treatments were replicated three times. Data on germination, tillering, height, girth, length of internodes and leaf number was collected monthly for six months for two seasons. Data on yield was collected by harvesting all the sugarcane from each plot at the 12th month after planting and recording the stalk biomass. Pol% was was generated by extracting juice from 10 randomly selected stalks per plot to obtain a homogenized, composite sample before adding lead sub-acetate clarifier and measuring the filtrate using a polarimeter before multiplying the recorded value by the corresponding pol factor. All the data was subjected to ANOVA using SAS 9.1 software; and means separated using Tukey’s test (P≤0.05). Finally, cost-benefit analysis was computed for all varieties under study. It was observed that use of gibberellic acid 4 and 7 and 6-benzyl adenine led to significant and or linear increasing growth, yield and quality (sucrose content) of sugarcane. It was also observed that the varieties differed in their response to application of the gibberellic acid 4 and 7 and 6-benzyl adenine. In yield, D8484 grown with GA4+7 and 6-BA at 4 litres per hectare recorded the best performance at 75.35 and 75.23 tons/ha in Seasons 1 and 2 respectively. EAK 73-335 recorded superiority in sucrose accumulation with pol% of 14.70% and 14.69 % in seasons 1 and 2 respectively when treated with GA 4+7 and 6-BA at 4 litres per hectare. There was no significant difference at 4 litres per hectare in all parameters under study. Application of gibberellic acid 4 and 7 and 6-benzyl adenine increased growth, yield and quality of the sugarcane varieties with D8484 recording the best overall performance and the highest net positive benefit-cost ratio at 3.7. Gibberellic acid 4 and 7 and 6-benzyl adenine increased yield by 11-22% and sucrose content by 3-6%. Therefore, it is recommended that variety D8484 and EAK 73-335 be grown and gibberellic acid 4 and 7 and 6-benzyl adenine at 3 litres per hectare be incorporated in the production of sugarcane in Kakamega County and areas with similar agro ecological conditions. In addition, there is need for evaluation of response of more cane varieties and in other agro ecologies. Further study is recommended on performance of ratoon crop previously applied with gibberrellic acid 4 and 7 and 6-benzyl adenine.
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    Effect of Nitrogen Fertilizer on Maize Performance, Nitrogen Use Efficiency and Soil Available Nitrogen Concentrations in Smallholder Farms in Rongo, Kenya
    (Kenyatta University, 2019) Nduwimana, Desire
    Reduced crop productivity among the smallholder farms is the main cause of food insecurity in Sub-Sahara Africa (SSA). Maize is a staple food crop in Kenya and is especially grown in the parts of North Rift and Western Kenya. In the Lake Victoria region and particularly in Rongo sub-county, maize potential production is low ranging between 0.8 to 1.6 tons ha-1. The low soil productivity is due to low soil fertility, low soil nitrogen, inadequate use of inputs such as mineral fertilizers, improved maize seeds, and inadequate agricultural practices to boost production. The purpose of this study was to determine the effect of nitrogen fertilizer on maize yields, nitrogen use efficiency (NUE), its effect on soil properties, and distribution in the soil profile and on soil microbial population. The study was carried out at Kambija and Koderobara in Migori County during the long rainy season from March–July, 2018. The experiment was arranged in a Randomized Complete Block Design with three replications. The treatments of N fertilizer (CAN) were at four levels (0, 25, 50 and 75 kg N ha-1). Tri- Superphosphate (TSP) at 10 kg P ha-1 was applied as blanket. Maize variety (Sc Duma 43) was used as a test crop. Data were analyzed with the ANOVA procedure using GenStat statistical software (15th edition) and treatment means separated using least significant difference at (P≤0.05). Results indicated that treatments with nitrogen fertilizer application significantly increased maize yields (p=0.001) at Kambija and (p=0.01) at Koderobara. Applied N fertilizer at 50 kg N ha-1 exhibited the highest maize yields compared to other treatments at both sites (4.34 t ha-1 for Koderobara and 3.41 t ha-1 at Kambija). High rates of N fertilizer increase soil acidity and decrease maize yields. Highest nitrogen use efficiency (NUE) was recorded at 25 kg N ha-1 with 23.84 at Kambija while at Koderobara was recorded at 50 kg N ha-1 with 22.61, in general NUE decreased with increased applied N rates. At Kambija, 75 kg N ha-1 had the highest N content in plant tissues with 2.07% in the heading stage while at Koderobara, the highest N content of 1.90% was recorded at 50 kg N ha-1. Due to rainfall variability, mineral N fractions (N03 − and NH4 +) were higher in sub-layers (10-20 cm and 20-30 cm depth) at seedling stages but at heading stages, N mineral concentrations were higher in top-layers (0-10 cm depth) in both sites. Plots fertilized at 50 kg N ha-1 recorded highest concentration of available N in the soils in both sites of the experiment. Soil microbial population was slightly increased by N fertilizer application and declined with increased soil depth. Based on the results of this study, application of N fertilizer at 50 kg ha-1 can be recommended among the smallholder farms for improvement of maize yield in Rongo-sub County, Migori County, and the catchment of Lake Victoria.