MST-Department of Agricultural Sciences and Technology

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    Management of Crown Gall Disease in Asteraceae Flower Cuttings in Nairobi, Kiambu and Nakuru Counties, Kenya
    (Kenyatta University, 2023-05) Wanza, Paul Magdalene
    Flower cuttings production in Kenya faces challenges in the marketing stage because of crown gall whose causal agent is Agrobacterium tumefaciens. Although crown gall is not a quarantine disease in Kenya, strict regulations in the market require that flower cuttings be free of the disease. The disease causes significant financial loss in nursery when large numbers of plants are affected. So far, losses of up to 80% have been recorded in nurseries. Crown gall disease can move systemically throughout the root system and destroy the plants completely. There are currently no effective management strategies for crown gall in the production of flower cuttings. This study aimed to determine the spread and effects of crown gall disease in the production of flower cuttings in Nairobi, Kiambu and Nakuru counties, Kenya and to evaluate the efficacy of various management strategies against the disease on Asteraceae family. A baseline survey was carried out between September and December 2018 while the laboratory and greenhouse experiments were carried out between November, 2018 and October, 2019. A laboratory experiment was set up in a flower cuttings production farm in Kiambu County to determine the action of various management strategies on Agrobacterium tumefaciens invitro. An innoculum density of 10 CFU/ml was immersed in 10mls the selected products and left to settle. After one day, 0.5mls of the suspension was pippeted and serial dilution done. A 0.5ml volume of the diluted cell suspension was plated on nutrient agar medium, incubated at 26°C for 5 days and the colony growth studied. A separate greenhouse experiment was set up at Kenyatta University to determine the effect of the various management strategies on crown gall on susceptible Argyranthemum frutescens. The plants were planted on peat and pumice media at a ratio of 25:75 in 3-litre plastic pots. Seedlings of Argyrathemum plants used in the experiment were obtained from a flower production farm in Kiambu County that grows them for export. The plants were prepared in a propagation chamber for 4 weeks before planting. The management strategies evaluated were Sunflower vegetable oil, KSP-Colloidal Copper, KOBEChrysophanol parietin, Copper oxychloride and Electro-Chemical Activated water. Innoculum was acquired from fresh galls and applied to plants by injuring using a hypodermic syringe then left to express symptoms for fourteen days. Application of the management strategies started after symptoms started showing. Data on disease severity and incidence was collected on a weekly basis in the greenhouse by counting galls and observing chlorotic symptoms development on the plants. In the laboratory, data on bacteria population on nutrient agar media was recorded for the different products tested. Survey data was analyzed using SPSS; laboratory and greenhouse data were subjected to ANOVA using SAS software and the treatments separated using Fisher’s protected Least Significant Difference (LSD) test at 5%. The survey results indicated that crown gall is prevalent in over 70% of the farms that produce flower cuttings. About 60% of the respondents reported the commonly applied management strategies of rouging and use of copper-based pesticides were not effective. Laboratory evaluation indicated Copper oxychloride and KOBE treatments were least effective (266 & 127 cells) compared to ECA water, KSP and oil treatments that recorded few cells (8, 16 & 37 cells). In the lab, combined application of ECA water and Oil killed all bacterial cells while oil alone suppressed bacterial growth partially (27 cells). KSP and oil combined appeared to antagonize each other and had 106 cells. In the greenhouse Copper oxychloride and KOBE were
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    Maize Grain Yield, Profitability and Selected Soil Properties as Influenced by Tillage Systems and Polyacrylamide Application in Meru County, Kenya
    (Kenyatta University, 2023-06) Gitaari, Mwingirwa Joshua
    Poor tillage practices and inadequate amelioration are threats to sustainable agricultural production in the central highlands of Kenya. The objective of this research was to evaluate how selected soil properties, maize grain yield and economic returns are affected by different tillage systems and polyacrylamide application. This study was carried in Meru county at the Meru University of science and technology farm during October to December SR (simn rains) of the year 2018 and March to May LR (long rains) of the year 2019. The test crop was maize. The experiment was a randomized complete block design (RBCD) with six treatments replicated 5 times. The treatments were; Deep strip till (DST); Conventional tillage and polyacrylamide application (CTPAM); No-till and polyacrylamide application (NTPAM); Deep strip till and polyacrylamide application (DSTPAM); the control being conventional tillage (CT) only and No till (NT). Soil moisture content, aggregate stability, particle density, total nitrogen and available phosphorous were measured up to a depth of 20cm. Bulk density and hydraulic conductivity were obtained at a depth of 17.0cm-22.3cm. Soil porosity was derived from the values of bulk density and particle density realized for the respective plots. Maize grain yield was measured at the end of each season to compare productivity under different treatments. Benefit cost ratio, gross margins and return to labour were calculated and compared for different treatments to establish the economic viability of different practices.
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    Screening Cassava Cultivars for Resistance to Cassava Viruses and Cassava Green Mites under Advanced Yield Trials in Kenya
    (Kenyatta University, 2024-10) Koros, Janet Cherotich
    Cassava is a perennial shrub with an edible carbohydrate-rich root growing in the tropical and subtropical areas of the world including Kenya. Africa accounts for over half of the world’s cassava production. Despite its economic significance, cassava is affected by a myriad of biotic and abiotic constraints among which are viral diseases and pests. The objective of the study was to identify high yielding cultivars resistant to Cassava mosaic disease (CMD), Cassava Brown Streak Disease (CBSD) and cassava green mites (CGM). Fifteen cassava cultivars (92/00061, 990005, Kileleshwa, TC 14, TC17, TC19, TC2, TC20, TC4, Thika2, Thika5, Thika6, TME419, Wakahiu3 and Wakahiu4) were selected from KALRO breeding site in Thika and local farmers, and planted at KALRO, Kiboko, a high pressure zone for CMD, CBSD and CGM. The cultivars were replicated in three blocks and data collected from 30 plants per block. Symptomatic descriptors were used to score plants that were affected by CMD, CBSD and CGM. Incidence and severity of both diseases and CGM was scored at 3 and 6 months after planting (MAP) while root tubers were harvested at 9 MAP. Disease severity (DSV) was assessed using a scale of 1 to 5 where 1 denoted no symptoms and 5 corresponded to severe disease symptoms while the disease incidence (DSI) was the percentage of the number of leaves infected. Disease development over time was monitored using area under disease progress curve (AUDPC) and area under severity index progress curve (AUSiPC). DNA and RNA were extracted from leaf samples for molecular detection of CMBs and CBSVs through Polymerase chain reaction (PCR) and Reverse transcriptase PCR (RT-PCR) respectively. Data was imported into Statistical Analysis Software (SAS) and variance analyzed using ANOVA. In this study, the varieties were classified as tolerant and susceptible. Genotypic differences for either diseases incidence (INC) or severity (SVY) and marketable root yield (MRY) was significant (P≤0.05) indicating that cassava yield and response to CMD and CBSD was genotype-dependent. Based on this, the genotypes were grouped into disease tolerant (DT) and disease susceptible (DS) classes with significantly higher MRY of 23.8 t/ha bulked by a DT genotype TME-419 and least MRY of 2.1 t/ha recorded in a DS cultivar Thika2. Incidences and severity of CMD, CBSD and CGM showed a negative correlation with yield and this confirmed the negative impact of both diseases and CGM to cassava yield. Molecular diagnostics using PCR and RT-PCR further confirmed the presence of CMBs and CBSVs in both tolerant and susceptible cultivars while the viruses were not detected in resistant cultivars in the present study. The variants of CMBs and CBSVs that were identified were EACMV & ACMV and CBSV & UCBSV respectively. Four (990005, TC4, TC14 & TME419) high yielding and DT cassava genotypes identified in the current study could potentially be used as parents in future breeding programs for introgression of tolerance traits in farmer preferred but susceptible local land races.
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    Black Soldier Fly Frass Fertilizer, Rhizobia Inoculant and Phymyx Effects on Soil Chemical Properties and Bean Yield in Kiambu County, Kenya
    (Kenyatta University, 2024-11) Chepkorir, Agnes
    Globally, bush bean (Phaseolus vulgaris L.) is a highly valued pulse crop that is utilized as an income earner, and for subsistence to address the global food security bottleneck. A key challenge to achieving maximum bush bean yield in the tropical region is soil degradation, due to limited soil micro and macro nutrients such as iron, soil phosphorus (P) in addition to low biological nitrogen fixation (BNF). Studies have demonstrated that soil nutrients especially P and micronutrients can be made available for crop uptake using black soldier fly frass fertilizer (BSFFF), and increased BNF success. Knowledge about BSFFF performance on leguminous crops such as bush beans is, however, scarce. This study assessed the relative performance of BSFFF and a commercial organic fertilizer (Phymyx) on growth, yield, BNF, and N uptake. Phymyx and BSFFF were supplied at the rates of 15, 30, and 45 kg nitrogen ha−1 . In addition, NPK fertilizer was applied at 40 kg N ha−1 , 46 kg P ha−1 , and 60 kg K ha−1 to function as a positive control and unfertilized plots as negative controls. In addition, Rhizobia inoculant was integrated into the experimental set-up to determine its interaction effects with organic and mineral fertilizers. Bush beans grown using BSFFF were the tallest (55.6 cm), with the broadest leaves (124.9 cm2 ), and the highest chlorophyll content (45.5 SPAD-Soil and Plant Analysis Development values). The utmost number of pods (24 pods) and seeds per pod (4 seeds) were achieved in plots that received BSFFF at the rate of 45 kg N ha−1 . Moreover, the application of BSFFF at 45 kg N ha−1 led to a 6, 8, and 18% increase in 100-seed mass, compared with NPK, with the equivalent rate of Phymyx and control, respectively. There were 67, 43, and 72% increases in seed yield in plots that received 45 kg N ha−1 of BSFFF, in comparison with those fertilized using a similar rate of Phymyx, NPK, and control, respectively. The total number of root nodules was 16, 10, and 27 times higher in BSFFF treatment supplied at 30 kg N ha−1 relative to a comparable rate of Phymyx, NPK, and control, respectively. Application of 45 kg N ha−1 from BSFFF also resulted in increased bush bean N uptake by 56 and 45% compared with Phymyx and NPK, respectively. Similarly, there was a 3–14 times increase in the number of effective root nodules and 25–60 kg more N fixed ha−1 in treatments fertilized using BSFFF at 30 kg N ha−1 compared with treatments with similar rate of Phymyx, and NPK as well as the control. The study revealed that using BSFFF in the production of bush beans can result in a $ 271–327 and 12–207% increase in gross and net income, respectively, compared with Phymyx fertilizer. In addition, using BSFFF can result in a 12–118% increase in the gross margin than if Phymyx is used for bush bean production. Therefore, the study showed that application of BSFFF could lead to 5–22 times higher returns on investment than the use of Phymyx for bush bean production. Hence, the findings demonstrate that BSFFF is more effective than NPK and Phymyx at improving the productivity of bush beans and is more economically viable compared with commercial organic fertilizer. This study lays a scientific foundation for adopting effective organic fertilizers like BSFFF for application in bush bean production systems
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    Geographical Information System-Based Land Suitability Assessment for Sunflower (Helianthus Annus) Production in Morogoro District, Tanzania
    (Kenyatta University, 2024-01) Nungula, Zephaline Emmanuely
    In Tanzania, the soil information available is inadequate and very specific in regions considered as highly potential areas and relies on a few collected scattered information over a big area which is not enough for agricultural land use planning locally. This study aimed to assess the appropriateness of land in Tungi Farm based in Morogoro District, Tanzania for sunflower production using a Geographic Information System (GIS). To determine appropriate areas for sunflower production, three criteria: soil properties (pH, organic carbon, total nitrogen, cation exchange capacity, available phosphorus, potassium, and soil texture), topography (slope and altitude), and climate (temperature and rainfall) were selected from the literature and employed in suitability analysis. The Analytic Hierarchy Process (AHP) method of the Multi-Criteria Evaluation was used to assign a weight to each criterion as per Saaty’s Table. Cumulative weights for each criterion were used in coming up with output maps using ArcGIS 10.8. Each criterion was reclassified and assigned a weighted value. Organic carbon, total nitrogen, cation exchange capacity, and potassium were found to be adequate. Topography and climate were suitable for the sunflower production. The results from land suitability gave S1 (vastly suitable), S2 (relatively suitable), and S3 (minimally suitable) of about 51% (1022 ha), 34% (671 ha), and 15% (307 ha), respectively. The suitability map in this study could be vital and helpful in management decision options. However, the criteria considered for land suitability evaluation were mainly based on the biophysical environment, and, hence, further studies can be carried out by integrating socioeconomic parameters to improve the suitability results of the study area.
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    Pest Population and Yield Dynamics of Selected African Indigenous Vegetables and Pulses under Different Climate-Smart Agricultural Practices in Murang’a County, Kenya
    (Kenyatta University, 2024-07) Muia, Eric Muthama
    Climate change and agricultural pests constitute key constraints to agricultural production in Kenya. These constraints lower the yield potential of locally grown food crops. African indigenous vegetables (AIVs) and pulses form key economically important food crops and dietary choices in Murang’a County in Kenya. Their economic potential notwithstanding, the production of AIVs and pulses is under threat due to the effects of climate change. This study determined the effects of climate-smart agricultural practices on the overall yields and pest status in AIVs and pulses in Ithanga location, Murang’a south sub county. Baseline demographics and crop cultivation data were collected using a semi-structured questionnaire from a sample of 226 respondents. Respondents were interviewed in their farms using open-ended questions to evaluate practices about the presence, diversity, challenges and farmer practices of AIVs and pulses cultivation. The studies were conducted during the short and the long rainfall seasons of 2021 and 2022. The on-farm experiments aimed to determine the effects of selected Integrated Pest management strategies (IPM) on the abundance and diversity of Arthropod pests attacking AIVs and pulses. Field experiments were set up to study the effects of selected climate-smart agricultural practices on pest’s dynamics and yields of AIVs and pulses. Five climate smart agriculture treatments were arranged in a randomized complete block design and replicated three times. Four IPM treatments were used in three replications to determine the effects of selected IPM strategies on pest’s diversity and abundance in AIVs and pulses. The study crops included; Solanum nigrum L (black nightshade), Vigna unguiculata L (cowpeas), Vigna radiate L (green grams) and Cajanus cajun L (pigeon peas). Study plots measuring 3 meters by 3 meters were set out and sowed with certified seeds from KALRO-Katumani. Sets of data were collected on pest’s damage, pest’s diversity and yield parameters. Analysis of variance tests (ANOVA) were conducted on the collected data using Genstat software version 22.0. Post hoc analysis was done to calculate significant means using Tukeys Honest significant Difference (HSD) at P< 0.05. Data obtained from the baseline survey were analyzed using IBM SPSS-28 Software. Results from the baselines survey showed that AIVs and pulses were present in the study area, and the respondents were aware that pests were attacking their crops. The logistic regression analysis showed socio-demographic variables such as the level of education, marital status and age had significant positive effect on respondent’s knowledge levels on CSAPs and pests control strategies (P≤0.05). The pest’s species diversity was determined using the Shannon Weiner Index of diversity. The results showed that, Whiteflies (Bemisia tabaci) were the most abundant pests followed by pea aphids (Aphis fabae), flower trips (Frankliniella occidentalis) and red spider mites (Tetranychus urticae) in decreasing order. The results showed plots installed with yellow and blue stick rolls had the lowest pest’s abundance and diversity while control plots recorded the most abundant and diverse pest’s species. Plots installed with sticky rolls had higher yields while the control experiment plots had the least amount of yields in both AIVs and pulses crops (P≤0.05). The results revealed that yield parameters such as plant height, number of pods and the primary yield were higher in plots installed with dry grass mulches followed by those applied with organic manure; control plots recorded the least yield parameters across the study crops (P≤0.05). The AIVs and pulses yield levels were significantly influenced by the climate smart agricultural products (CSAPs) used.
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    Integrated Soil Fertility Management Practices Effects on Soil Chemical Properties and Maize (Zea Mays L.) Yield in Machakos County, Kenya
    (Kenyatta University, 2024-01) Wamalwa, Stephen Wanjala
    Most of integrated soil fertility management (ISFM) studies have been carried out at plot level, resulting in recommendations with minimal application due to the heterogeneity of smallholder farms in semi-arid Kenya. A research study was conducted in four (4) seasons between 2016-2018 with the aim to determine the effects of selected Integrated Soil Fertility Management (ISFM) practices on soil chemical properties and maize yields at the watershed level. The ISFM treatments included combinations of maize monocrop/pigeon pea intercrop cropping system; cattle manure applied at 2 ton ha-1 ; N-P fertilizer applied as 40 kg ha-1 of diammonium phosphate (DAP 18:46) and tied ridging (TR). A completely-randomized design (CRD) was adopted with nine for the following treatments;- (1) maize monocrop & No fertilizer (control) (2) maize monocrop & DAP (3) maize monocrop, DAP & TR, (4) maize monocrop, DAP & manure (5) maize monocrop, DAP, manure & TR; (6) maize/pigeonpea intercrop & DAP, (7) maize/pigeonpea intercrop, DAP & TR, (8) maize/pigeonpea intercrop, DAP & manure, (9) maize/pigeonpea intercrop, DAP, manure & TR. Soil pH, carbon (SOC), Total nitrogen (TN) and phosphorus (P). Exchangeable Potassium (K), Calcium (Ca), Magnesium (Mg), Sodium (Na) and micros Manganese (Mn), Copper (Cu), Iron (Fe), Zinc (Zn), and maize yield data collected was subjected to analysis of variance (ANOVA) using GENSTAT version 15 and means separated using Duncan's Multiple Range Test at (LSD 0.05). Results showed that the effect of ISFM practices on soil chemical properties and maize yield varied. Organic C, TN, Ca, Na, Mn, Cu, and Fe significantly (p<0.05) increased due to imposed ISFM practices. The maize yields were higher in short rain (SR) than long rains (LR). The treatment combination DAP, manure, tied ridging with maize-pigeon pea intercrop was best in improving soil organic carbon (0.79%), total N (0.1%). The application of DAP, manure, tied ridging with sole maize resulted in organic C increase by 0.78% and total N by 0.093%. The treatment combination DAP, manure, tied ridging with maize-pigeon pea intercrop achieved the maximum maize grain yield of 2.10 ton ha-1 and 2.16 ton ha-1 in the SR 2016 and SR 2017 respectively, while in LR 2017, maize grain yield was 2.03 ton ha-1 . Further, it resulted in the most significant marginal yield increase of 0.12 t ha-1 . This increase raised the maize grain yield from 1.56 t ha-1 to 1.68 t ha-1 in 2016 and 2017 SR, respectively. This was attributed to the improved soil fertility of the watershed due to the inputs and the N supply from the biological nitrogen fixation process of pigeonpea. Farmers in semi-arid locations can only utilize 10% of the suggested inorganic nitrogen rates if they employ a combination of manure and DAP with tied ridging on maize-pigeonpea. Furthermore, it is necessary to economically validate these ISFM practices before upscaling.
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    Virulence, Diversity and Management of Fusarium Oxysporum F.Sp. Cubense Infecting Bananas in Selected Counties in Central and Eastern Kenya
    (Kenyatta University, 2023-10) Malaka, Musime Samuel; Maina Mwangi
    Banana belongs to Musaceae family and is cultivated worldwide supporting the 1ivelihood.s of many people and the economies of many countries. One of the pathogens that is significantly reducing banana yield in Kenya is Fusarium oxysporum f.sp. cubense (Foc) that causes Fusarium wilt of bananas (panama disease). There are currently no_long—term control mechanisms for panama disease. Critically, there is very little information on the distribution of Foc races in Kenya. Carbendazim based fungicides have been used as a control measure but they have not given a reliable and long term management effect. Carbendazim has a single mode of action, hence high chances of Foc developing resistance. This study determined the pathogenicity, physiological races of Foc and the in vitro and greenhouse efficacy of Trichoderma harzianum, T. asperellum and 7. viride for management of Foc. Laboratory experiments were done at the Horticulture Research Institute (HRI) in Kandara, Kenya in May 2022. The tissue culture and greenhouse experiments were done at Coffee Research Institute. The molecular work was conducted at Kenyatta University Plant Transformation Laboratory. The genomic DNA was extracted from the 7 days old monosporic fungal cultures. The PCR amplification was done using Foc specific primers for the three Foc races by targeting hypothetical protein, TEF-1a, and SIX8a gene respectively. A total of 57 isolates were collected. Conidia for pathogenicity test were harvested from 14 days old Fusarium cultures on PDA media using two layered cheese cloth, the greenhouse pathogenicity experiment was done using the root dipping method. For management in the greenhouse, the test products and Foc were applied directly into the soil. All isolates were tested in four replicates of one plant per isolate. Disease severity was recorded weekly for 20 weeks. A disease scale of 1-5 was used during data collection. In vitro efficacy of fungicides was evaluated using poisoned food technique. The fungal radial growth for in vitro efficacy was recorded daily for one week. The data on plant biomass, biological and chemical control treatments and the data on pathogenicity test experiment were subjected to one-way ANOVA. The results were compared using Student—-Newman—Keuls (SNK) test at P<0.05. All the tested isolates were virulent. The isolates that were highly pathogenic based on data on external and internal symptoms included, AP009, CV005, KL002, KL004, AP007, EM001, AP006, CV001, CV004, and AP002. Data on plant biomass revealed that the discase caused by the pathogens also decreased the plant biomass. All the test fungicides; 7. asperellum at 0.1% rate, T. viride at 0.6% rate, T. harzianum 0.1% rate, and Carbendazim (500g/1) were effective in management of Foc. The results indicated that 7. viride, T. harzianum, T. asperellum and Carbendazim (500g/1) recorded a significantly (P<0.05) higher control of Foc compared to the negative control at 58.57 %, 61.38 %, 72.68 %, and 78.94 % respectively. The percentage control of Foc using T. viride, T. harzianum, and T. asperellum, was significantly p < 0.05 lower compared (0 Carbendazim (500g/1). A total of 31 isolates collected were confirmed to belong to Foc racel. This study generated new knowledge on the diversity of Foc in banana growing regions of Central and Eastern Kenya as well as identifying potential biological control agents against panama disease. These findings will enable farmers to access a wider range of management strategies for long-term control of panama disease.
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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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    Evaluation of Rapid Propagation Schemes and Spacing for Optimization of Cassava Pre -Basic Seeds Production in Rwanda
    (Kenyatta University, 2023-06) Uwimana, Josette; Joseph Onyango Gweyi; Silver Tumwegamire; Benjamin Danga
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    Management of Crown Gall Disease in Asteraceae Flower Cuttings in Nairobi, Kiambu and Nakuru Counties, Kenya
    (Kenyatta University, 2023-04) Wanza, Paul Magdalene; Maina Mwangi; Nicholas Korir
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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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    Soil Chemical Properties and Sunflower (Helianthus Annuus L) Productivity Responses to Sunn Hemp Intercropping and Mineral Fertilizer Application in Dodoma, Tanzania
    (kenyatta university, 2023) Chappa, Luciana Raphael; Jayne Mugwe; Harun Gitari
    Sunflower (Helianthus annuus L.) is one of Tanzania's high-potential cash crops. Nonetheless, nutrient depletion, especially nitrogen (N), is limiting its productivity. An integrated soil fertility management technique that entails intercropping sunflower with a leguminous plant like Sunn hemp (Crotalaria juncea) and the application of mineral N fertilizer can boost N availability for crop uptake hence resulting in high crop productivity. The study was conducted in the semi-arid -Dodoma region in Tanzania where it adopted a randomized complete block design (RCBD) with six treatments each replicated four times. These treatments were T1; Control (sunflower pure stand) without mineral nitrogen (N) fertilizer, T2; Sunflower-Sunn hemp intercrop under 1:1 row ratio without fertilizer, T3; Sunflower-Sunn hemp intercrop under 1:1 row ratio with fertilizer, T4; Sunflower-Sunn hemp intercrop under 2:1 row ratio without fertilizer, T5; Sunflower-Sunn hemp intercrop under 2:1 row ratio with fertilizer and T6; Sunflower pure stand with fertilizer. Data that were collected are soil chemical properties (soil pH, organic carbon, total nitrogen, available phosphorus, potassium, calcium, magnesium, and sodium), sunflower growth and yield parameters (plant height, leaf area, number of leaves per plant, sunflower head diameter, N uptake by sunflower leaves, achene yield, number of seeds per plant, weight of seed per plant, and stover yield), economic returns (gross income, net income, and benefit-cost ratio-BCR). The data from this study were tabulated in excel and then subjected to analyses of variance. The means of treatments that were significant were distinguished by using the least significant difference (LSD) at a 95% confidence interval. The results indicated that except for soil pH, the other chemical soil properties tended to increase significantly (p ≤ 0.05) under all the treatments containing integrated approaches like Sunn hemp and N fertilizer application relative to the sunflower pure stand treatment across the sites. Regardless of the site, T6 and T3 showed the best performance based on the sunflower growth and yield. For instance, at Kongwa the sunflower leaf area was highest in T3 (285 cm2) and T6 (282 cm2) with T4 having the least value of 149 cm2. A similar trend was observed for the number of Sunflower seeds per plant, the weight of sunflower seeds per plant, Sunflower achene yield, and Sunflower stover yields with the best- performing treatments being T6 and T3. T5 and T2 had the highest (US$ 278 ha-1) and the lowest (US$ 205 ha-1) cost of production. Economically, Kongwa outperformed Bahi. Specifically, based on treatments, T3 had the highest gross income both at Kongwa (US$ 3412 ha-1) and Bahi (US$ 1756 ha-1). This translated into respective net income and BCR of US$ 1639 and 698, and 7.50 and 3.20. This study's findings will help rural poor farmers achieve better economic returns, hence reducing poverty.
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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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    On- farm integrated management of fruit flies (tephritidae) infesting pumpkins (cucurbita maxima duch.) in Yatta and Masinga Sub- Counties of Machakos County, Kenya
    (Kenyatta University, 2023) Waithaka, Alice Nduta; Namikoye Everlyne Samita; Mary Mwari Guantai; Muo KASINA
    Pumpkin is an economically important crop in Machakos County. The crop is highly nutritious, mainly grown by smallholder farmers for household use. Their production is however constrained by fruit fly infestations particularly the melon fly, Zeugodacus cucurbitae (Coq.). The current study focused on the on-farm integrated management of fruit flies infesting pumpkins Cucurbita maxima in Yatta and Masinga Sub- Counties. The key objectives of the study were: (1) determining farmers’ knowledge, perception and control strategies of fruit flies infesting cucurbits in Machakos County, (2) determining the presence and onset of fruit flies on pumpkin farms in Machakos County and (3) evaluating the effect of integrated pest management (IPM) strategies on the pest density and overall yield of pumpkin. In the first objective, a household survey of 95 cucurbit farmers was conducted using structured questionnaires. In the achievement of the second and third objectives, on- field experiments were carried out in the low and medium NDVI classes, across Yatta and Masinga Sub- Counties. The experiments were conducted for two growing seasons (October 2019-March 2020 and March 2020-July 2020). Two treatments were used for the third objective; IPM and control replicated eight times in each NDVI class. The IPM package comprised of lynfield traps with cuelure® laced with malathion®, Metarhizium anisopliae strain ICIPE 69 (mazao campaign®), and fruit fly mania™, a protein bait incorporating spinosad (tracer®). The collected data was analyzed using the statistical package for social sciences (SPSS) and R software. The farmer respondents were not aware of IPM strategies for fruit fly control (91.4%). However, 48.8% of the them reported lack of training as the main constrain hindering adoption of IPM practices. Most of the respondents 75.5% therefore relied on chemical insecticides use for fruit fly management. In the first season, fruit flies were reported in pumpkin plots from the second week of flowering across both NDVI classes. However, in the second season, fruit flies were reported in the farms from the first week of flowering. Zeugodacus cucurbitae was the most abundant fruit fly species from trap catches (75%) and fruit incubation (69.01%). Although, Z. cucurbitae catches/trap/day were significantly higher in control plots than in IPM plots, the yields did not differ significantly between the treatments. In conclusion, the study states lack of training as the major constraint inhibiting adoption of IPM for fruit fly management in the County. The study concludes that fruit fly infestations by Z. cucurbitae starts as early as the onset of flowering especially when suitable host is present after temporarily being absent. Additionally, the use of IPM plan significantly reduced fruit fly population. The study therefore recommends training on the IPM strategies be conducted to equip cucurbit farmers’ as independent decision- makers in pest management. Farmers should initiate fruit fly management as soon the crops start flowering to minimize yield losses. Finally, awareness on the effectiveness of the IPM plan should be promoted widely among cucurbit farmers to enhance adoption.
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    Potato (solanum tuberosum l.) growth and yield as influenced by bioslurry and inorganic fertilizer in Taita Taveta County, Kenya
    (Kenyatta University, 2023) Mwakidoshi, Emmanuel Randy; Harun Gitari; Esther Muindi
    Biogas slurry procured from livestock refuse after bio digestion has a great potential of mitigating climate change by reducing methane gas emission from manure use and nitrous oxide from inorganic fertilizer use thus, improving crop growth, yield, and soil productivity. A field study was conducted on farmer’s fields at Werugha and Wusi-Kishamba wards in Taita Taveta County, Kenya to investigate the effect of inorganic fertilizer and bioslurry on potatoes (Solanum tuberosum L.) growth and yield. Four treatments: bioslurry + DAP (Di-ammonium phosphate); sole bioslurry, sole fertilizer (DAP), and control (without amendment) were laid out in a Randomized Complete Block Design with five replications. 100% DAP [18:46:0] fertilizer was used at a rate of (5g/hill) and 100% Bioslurry was applied at rates of (400mls/hill) at planting. In addition, a survey questionnaire was developed and administered to 120 smallscale farmers within the two wards. Biophysical data was collected on plant growth (plant height, leaf length, and the number of leaves per plant), and yield (marketable and unmarketable tubers, and the number of tubers plant−1). The survey and biophysical data obtained from the study were analyzed using Statistical Package for the Social Sciences (SPSS) and GenStat statistical software, respectively at a 5% probability threshold. Results showed that the use of bioslurry had not been well adopted by farmers from the two wards as only 18% responded to using bioslurry on their farms whereas 78% relied on chemical fertilizers and other forms of manures such as farmyard manure. However, even those using slurry had since been reported to have challenges with the use and application of the slurry. The 36% of farmers who applied bioslurry alone did so due to its availability considering the high cost of inorganic fertilizers while those who combined it with inorganic fertilizers had faith in chemical fertilizers and that they aimed at achieving high crop yields. The major challenges farmers faced while using slurry on their farms were reported to be on lack of knowledge on the exact quantity to be applied per unit area and on the storage of excess slurry from biodigesters. This implied that even though slurry was available, it was still not useful to the farmers due to under/over application and poor storage. The field experiment reviewed that the application of combined bioslurry and DAP fertilizer significantly (p ≤ 0.05) improved potato growth and yield. The results indicated the superiority of combined bioslurry + DAP fertilizer use over the sole application of either of the two amendments. For instance, the plants that received these inputs in combination were taller (80 cm) than either those treated with sole slurry (61 cm) or sole fertilizer (66 cm). Subsequently, this resulted in a higher (23.3 t ha−1) total yield in bioslurry + DAP treatment compared to respective intermediate values of 16.8 and 18.7 t ha−1 for sole slurry and sole fertilizer and the least record of 14.2 t ha−1 in control. The study, therefore, recommends the synergistic application of bioslurry and inorganic fertilizer (DAP) to potato crops for optimal crop growth and production