School of Agriculture, Natural Resources and Environmental Studies

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    Occurrence and impact of golden dodder (cuscuta campestris yunker), invasion on species diversity of trees and shrubs in homa- bay county - Kenya
    (2022-11) Orwah, Pamela Akoth
    C. campestris is a parasitic vine growing rapidly entwining and parasitizing on its host plants by inserting haustoria into the host plants’ stem and leaves. This study focused on the occurrence and impact of Cuscuta campestris on the diversity of host trees and shrubs in Homa-Bay County, Kenya. The overall objective was to investigate the occurrence and impact of Cuscuta campestris yunker, invasion on species diversity of trees and shrubs with specific objectives of the study as;1) To establish the occurrence and distribution of C. campestris invasion on trees and shrubs. 2)To determine the species diversity and characteristics of trees and shrubs parasitized by C. campestris. 3) To determine the effect of C. campestris on chlorophyll content and leaf biomass of infected host plants. The study was conducted in three Sub-counties, Rachuonyo North, Homa Bay town and Suba North Sub-counties. Descriptive Survey and Quasi Experimental Research Design were used. Purposive sampling technique was employed in selecting the study sites. Data was collected through laboratory analysis, structured interviews, questionnaires and field observations. Chlorophyll content was measured for both infected and uninfected plants using spectrophotometer while leaf biomass was measured for both dry and fresh weight of infected and uninfected samples. Data for climatic condition was obtained from National Meteorological Department - Homa Bay County Branch to show the variation in the occurrence and distribution of C. campestris on host plants with annual rainfall and temperature variability. Quantitative data was descriptively and inferentially analyzed in form of one-way ANOVA -SPSS-20. The study established that occurrence and distribution was more intense in shrubs, T. peruviana and E. tirucalli species than in host trees. Mean chlorophyll amounts were observed to decline from the uninfected to infected with chlorophyll a declining from 3.97 to 1.59 mg/g, b from 2.65 to 1.18 mg/g and total chlorophyll from 6.62 to 2.76 mg/g. Leaf biomass significantly decreased in infected host plants with mean fresh weight of 17.61g in infected significantly different, F (1, 4) = 235.74, p< .05, from the mean fresh weight of 24.23g in the uninfected while the mean dry weight of 5.55g in infected was significantly different, F (1, 4) = 159.72, p< .05, from mean dry weight of 7.87g in uninfected shrubs. The results demonstrated that C. campestris is detrimental to plant biodiversity. The study conclusions were, occurrence and distribution of C. campestris is less dependent on climatic variability but heavily dependent on host-plant, C. campestris has rich hostplant species diversity with wide range of characteristics from varied habitats and that Cuscuta has significantly affected leaf chlorophyll content and leaf biomass of infected host plants thus impose significant destruction on plant growth and loss of biodiversity. The study recommends substitution of preferred host plants with hardly infected plants, sensitizing of residents on the impacts for the need to design appropriate sustainable management protocol and legislation to classify the weed as noxious plant in Kenya. Further research to focus on determining the nutrient composition in preferred host plants to enable further understanding for effective management.
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    Effects of water quality on the diversity, abundance and distribution of benthic macro invertebrates along the shores of Lake Victoria in Homa-bay county Kenya
    (2022) Owalo, Patricia Okune
    Human-induced landscape alterations adversely affect habitat structure and functions in freshwater ecosystems, as well as the flow regime in the Lake Victoria basin. The massive discharge of wastewaters and other pollutants from the surrounding basin do interfere with ecological balance in parts of the lake thereby causing adverse impact on benthic macro-invertebrates especially along the lake shores. The overall objective of this study was to investigate the impact of water quality on the diversity, abundance and distribution of benthic macro-invertebrates along the Lake Victoria shores in Homa-Bay County, Kenya. Specific objectives were to: analyse the physico-chemical parameters of water quality, determine the diversity of benthic macro-invertebrate species, analyse the abundance and distribution of benthic macro-invertebrate species, and determine the impact of selected physico-chemical parameters on diversity, abundance and distribution of benthic macro invertebrate species along the shores of Lake Victoria, Homa-Bay County. The study adopted quasi experimental research design. Stratified random sampling was used to collect samples along Oluch-Kimira River Mouth, Homa Bay sewage discharge point and Mbita beach east of the course way at monthly intervals from September 2019 to February 2020. Samples of benthic macro invertebrate were collected using sweep net and grab sampler, preserved and laboratory identified using stereoscope, while water samples were collected using Van Dorn water sampler and nutrient analyses done using APHA (2017) standard methods at KMFRI. Physico-chemical parameters were measured in situ using YSI meter and Secchi disc for light intensity. Data was analysed using descriptive statistics, Shannon-Weiner Index, one way ANOVA, Turkey HSD post hoc and Canonical correspondence analysis (CCA). The study established that there was significant difference in diversity (F (2, 15) = 12.49, p= 0.001) and abundance and distribution of benthic macro invertebrate species (F (2, 15) = 14.41, p< 0.05) along the shores of Lake Victoria. Oluch-Kimira river mouth and Homa Bay sewage discharge point recorded significantly lower DO levels (4.0±0.46 to 6.2±0.19 MgL-1) compared to Mbita beach east of the course way (5.6±0.23 to 7.7±0.17 MgL-1), high nutrient load concentration, turbidity (317.47 NTU) and electrical conductivity (147.86 µScm¯¹) along Oluch Kimira river mouth, high dissolved oxygen concentration along Mbita beach east of the course way, and lower dissolved oxygen concentration along with high pH (8.47) at Homa Bay sewage discharge point. Benthic macro invertebrate diversity was relatively high along Mbita beach east of the course way with cloeon simile, Agrion splendens, Anodonta cygnea, Baetis and Caenis moesta being the most dominant species, whereas along Homa Bay sewage discharge point Spaniodoma sp, Sphaerium sp, Tubifex tubifex, Anodonta cygnea, Polycentropus and Naids were most dominant, and along Oluch Kimira river mouth, Anadonta cygnea, Tubifex tubifex, Melanoides tuberculata, Caenis moesta, and Sphaerium sp were dominant. The study concludes that changes in selected physico-chemical parameters and nutrient loads concentration along the shores of Lake Victoria influence the diversity, abundance and distribution of benthic macro invertebrates. The study provides baseline data for evaluating the trends in water quality and related changes in benthic-macro invertebrates and aquatic biodiversity along Lake Victoria shores in Homa Bay County, Kenya.
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    Prevalence of parasitic infection in farmed nile tilapia, oreochromis niloticus (linnaeus, 1758) and other selected environmental factors associated with their transmission in winam gulf of lake victoria
    (2021) Ngodhe, Omari Abongo Steve
    The general objective of the study was to assess the level of parasitic infection and farmer management practices in farmed Nile tilapia (Oreochromis niloticus) and some of the selected environmental factors associated with their transmission in Winam Gulf of Lake Victoria, Kenya. Selected water quality parameters from the 20 ponds, 30 cages and wild were measured in-situ using electronic meters and parasitological examination done according to standard procedures. A total of 96 questionnaires supplemented with direct observations were administered to fish farmers to assess the status of fish farming and management practices that could influence the occurrence of fish parasites. A total of 720 fish were purchased from fishermen, cage and pond farmers and examined for parasites. Temperature, DO, TDS and Salinity differered significantly in the different study areas (p<0.05) while pH registered an insignificant difference between the culture systems (pond and cage) and the wild (p>0.05). This was attributed to the homogeneinity of the study area experiencing the same climatic conditions. The environmental variables were within FAO’s recommended limits for fish production. The class trematoda which included: Gyrodactylus spp., Dactylogyrus spp., Tylodelphys spp., Diplostomum spp., Clinostomum spp. and Naescus spp. were the most common and prevalent parasites in both ponds and cages of the Winam Gulf while Amirthalingamia spp. and Diplostomum spp. were the most common and prevalent in the wild. This was due to the presence of piscivorous birds seen more often around and overstoking, which increases the spread and transmission of parasite from one fish to another. The parasitic infestation rate was not significantly different between the ponds and cages (p>0.05) while there was a significant difference between the two culture systems and the wild fish of Winam Gulf. Parasitism or parasitic infestation did not affect the fish condition factor in all the study areas. This was due to very low mean intensities recorded and shorter period of exposure to parasitic infestation as most farmers have not been to fish farming for a very long time especially the cage farmers. Some management practices identified as possible risk factors for occurrence of fish parasites included: overgrown vegetation, overstocking, failure to change water within a production cycle, cleaning and treatment after harvesting, poor quality feeds and feeding, sharing of farm equipments and materials, lack of awareness on fish parasitism and signs of the infected fish. For Kenyan national government to explore on blue economy and achieve the vision 2030 on food security and poverty reduction by 2030, efforts to promote commercial cage and pond fish culture enterprises in Winam Gulf of Lake Victoria and other water bodies must be enhanced on condition that the cages are sited in deep waters of the gulf with low cage concentration in a particular site and reduced stocking densities in order not to compromise the environmental quality.The farmers should also be equipped with proper management practices to maintain acceptable water quality and avoid transmission of fish parasites.
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    Screening of sorghum (sorghum bicolor) genotypes for resistance to covered kernel smut disease (sporosorium sorghi) for western kenya
    (2021) Okong’o, Caroline Auma
    Sorghum is an important food security crop for arid and semi-arid tropics but its production is hampered by covered kernel smut disease (CKSD) which is a seed borne panicle disease caused by fungus Sporosorium sorghi. The fungus attacks susceptible sorghum genotypes causing yield losses estimated at 43% in Western Kenya posing a major threat to sorghum production. The current control measures involve the use of chemical, cultural and biological methods but they are costly, and environmentally unfriendly, laborious and ineffective and hence not sustainable. Most researchers have proposed the use of resistant genotypes which is affordable and sustainable to small scale farmers, but such varieties are not available. Thus, a study was conducted in 2019 growing seasons in order to determine the response of selected sorghum genotypes to CKSD under field and greenhouse conditions, and determine heterosis for agronomic traits in sorghum single crosses developed from tolerant and susceptible varieties to control CKSD as a first step to initiate introgression breeding for tolerance to the disease. A total of 15 genotypes were evaluated in two disease hotspot areas of Migori and Homa Bay counties in a Randomized Complete Block Design (RCBD) replicated thrice. Each genotype was planted in a 2.25 X 4m plot at spacing of 75 X 20cm. For controlled experiment in the greenhouse, the 15 genotypes were planted in pots in a Completely Randomized Design (CRD) also replicated thrice. In both cases, data on disease incidence, severity and grain yield was collected per genotype and analyzed using R for windows (version 3.6.2) and means separated using Tukey’s test. Resistant genotypes were identified then crossed with the susceptible lines to incorporate covered kernel smut disease resistance through hand emasculation. Results showed significant differences among genotypes for disease incidence, severity and yield parameters. The disease incidence was evenly distributed and it varied significantly (p<0.001) between the sorghum genotypes per location. A range of 0-60% and 0-69% disease incidence was recorded under field and greenhouse conditions with Nyadundo2 and C26 having 60% and 69% respectively, while T53, T30, IS3092, N4 and N68 had 0% incidence. Similarly, severity also followed the same trend with Nyadundo 1 having a score of 5 while T53 scored 1. T53 produced the highest mean grain yield of 3.63t/ha while Seredo had the lowest mean grain yield of 0.20t/ha. Significant heterosis for seed weight, panicle traits, plant height and 50% days to flowering were observed on the eight F1 crosses. Various crosses showed significant heterosis in different traits. For instance, MUK60 X N13 had negative heterosis and heterobeltiosis for 50% days to flowering and plant height while NYADUNDO1 X IESV92038/SH had a positive heterosis and heterobeltiosis for panicle traits. This study has identified and developed six crosses which are potential sources of resistance for covered kernel smut disease that can be utilized to significantly improve yields in hotspot areas of western Kenya or for further breeding.
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    Impacts of Rongo University Establishment and Development on Land Use and Land Cover Changes in Rongo Municipality, Migori County, Kenya
    (2021) Ochola, George Ouma
    In the last two decades, there has been an exponential expansion in terms of the geographic distribution and demographic expansion of Universities in Kenya. The expansion of universities in space and time needs to be well planned in order to minimize adverse environmental effects such as mushrooming of informal settlements and slums caused by land use and land cover (LULC) changes. Rongo University has seen rapid increase in human population and development of infrastructure since its establishment in 2011. Except this study, the impact of such development in and around the university and in deed in Rongo Sub-County at large has not been well investigated. This lack of information hinders proper environmental planning and management of the mushrooming developments in this sub-county even as environmental degradation continues. The study’s specific objectives were: i. to assess how the national policies and regulations have guided establishment of universities in Kenya; ii. to examine the nature and extent of LULC changes in Rongo University’s local environment with reference to establishment and development of the university; iii. to assess the local environmental impacts resulting from LULC changes influenced by Rongo University and finally iv. to develop a spatial and environmental management plan to mitigate negative impacts of the University presence on the local environment. The study adopted mixed design method which relied on primary data from key informant interview, focus group discussions, field observations, geographic information system and remotely sensed imagery. Remotely sensed data was acquired through downloading the Landsat images from United States Geological Survey website. Supervised classification method was used where a shape file was created and Areas of Interest determined. The images were classified for the time interval that was 2010-2013 by drawing polygons with the help of colour key on the image using interactive supervised classification. Secondary data was gathered from already published literature through review. Thematic content analysis technique was used to analyze qualitative data from focused group discussions and key informant interviews. Quantitative data was analyzed by use of statistical package for social scientists. Remotely sensed data was analyzed by use of IDRISI Selva 17.0 in which the classified images in Arc map 10.3.1 were converted to ASCII for image display. The study established an increase of 48.52% in settlement from 2010 to 2018. Significant loss of 48.86% in plantation/farmland was also noted and open land decreased by 12.87% between 2010 and 2018. Similarly, the study has shown that there is greater need for public sensitization considering that 64% of the respondents contended that the state of the environment is changing from bad to good implying a change from a natural environment to a built up environment is preferable. The study concluded that there is inadequate compliance with existing legal framework and policy on land use and land cover resulting in mismatching development and environmental sustainability as demonstrated by environmental degradation. In this respect, the study recommends sustainable development which is informed by compliance to legal framework, monitoring and evaluation of environmental policy and regulations guiding land use and land cover changes. Similarly, Rongo University should showcase environmentally sustainable development initiatives in partnership with relevant authorities for instance, Rongo Municipality and Migori County government through outreach and information dissemination system.