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Doctor of Philosophy in Agriculture

Permanent URI for this collectionhttp://41.89.31.6:4000/handle/123456789/162

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Start date: 2020End date: 2025

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    Determination Of Yield Performance and Regeneration Potential of Upland-Grown Arrowroot [Colocasia Esculenta (L.) Schott] In Kenya
    (KeMU, 2025) Joseph, Macharia Kinyoro
    Despite arrowroot's potential yield, its production in Kenya remains limited, primarily due to the small area available for cultivation and the basic planting techniques employed. The objectives were to determine the optimal planting depth and the most effective GA3 dosage for inducing propagule production. Field and pot experiments were conducted in 2023 and repeated in the 2024 main cropping seasons at the Teaching and Research station, Egerton University, Nakuru County, to evaluate upland-grown arrowroot for varying planting depths on arrowroot tuber yield and yield components. A field experiment was laid out using a randomized complete block design with four replications. The factors included pit depths of 20 cm, 30 cm, 45 cm, and 60 cm. Data collected included shoot parameters, corm yield, and yield components. The planting depths significantly influenced the corm weight per plant: 60 cm (2.67 kg), 45 cm (2.02 kg), 30 cm (1.24 kg), and 20 cm (0.35 kg) yielded the heaviest corms per plant in fresh weight. The depth also affected shoot parameters significantly (p ≤ 0.05). The same trend was maintained for corm yields per hectare: 60 cm (44.63 t ha-1), 45 cm (38.43 t ha-1), 30 cm (29.58 t ha-1), and 20 cm (7.54 t ha-1) were significantly different from each other (p ≤ 0.05). A second pot experiment was conducted in a greenhouse involving two arrowroot cultivars, Girigaca and Kienyeji. The results show that the interaction between the cultivar and GA3 was significantly different for the number of rhizomes, length, and number of nodes per rhizome (p ≤ 0.05). However, the girth of the rhizome was not significantly affected (p ≤ 0.05). Spraying gibberellic acid (GA3) at 750,500, 250, and 100 ppm significantly increased the number of rhizomes produced by Girigaca, with a dose of 750 ppm producing the highest number of rhizomes. The Kienyeji cultivar failed to produce rhizomes but developed suckers. The interaction between the Girigaca cultivar and spraying with distilled water (Control) produced suckers and no rhizomes. Furthermore, a study was conducted to determine the influence of GA3 treatment on the mother plant on the sprouting capacity, plant height, and leaf area of the plantlets produced from rhizomes. The results showed that the interactions between GA3 and the media significantly affected the number of sprouts (p ≤ 0.05), but not the height and leaf area of the plantlets. The outcomes suggest that the rhizomes obtained from arrowroot treated with GA3 influenced the sprouting of rhizome nodal cuttings. The river sand used for sprouting performed better than the sawdust in the initial growth phases, but the latter is a viable alternative. The study demonstrated that planting depth has a significant impact on the yield of upland arrowroot, with deeper pit depths yielding better results for corm weight and overall production. It is recommended that (1) farmers for upland arrowroot production adopt 30 cm wide and 30 to 60 cm deep moisture pits for enhanced yields, (2) gibberellic acid may be sprayed on potted arrowroot plants for rapid, large-scale rhizome production of suckers. But additional research is needed on cultivar maturity and plant density.
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    Effects of Exotic Tree’s Growth Morphology and Litter Substrate Quality on the Adjacent Native Grasses
    (KeMU, 2022-10) Gichuki, Philip Mwangi
    Light irradiance, water and litter substrate quality are major plant nutritional factors that control above and below ground plant resources. The study sought to find out the effects of exotic tree’s growth morphology and litter substrate quality on the adjacent native grasses. Specific objectives were; to determine the effect of the adjacent tree canopy structure and the above ground processes that affect the delivery of resources to the adjacent native pasture, to analyze the adjacent tree roots structure and their below ground effects on the adjacent native pasture and to analyze the adjacent tree litter quality and below ground processes that affect the delivery of resources to the adjacent native pasture. Three native grass study sites adjacent to Eucalyptus, Cypress and Acacia were marked for the study. There was an additional site with no tree nearby that acted as control. Their crown, roots and litter substrate quality were studied. This was done from a distance of 1m to a distance of 60m away from the tree stand. Crown structure such as the diameter, breast height, total height, foliage transparency, die backs, position, exposure and density were analyzed. Canopy light radiation was determined by measuring photosynthetic active radiation and stomata conductance of the adjacent native grass. Roots growing structure such as branching density, diameter of fine roots, length, and depth were studied. Other roots characteristics such as exudates, fungal biomass, Ecto-mycorrhizal and Arbuscular mycorrhizal association were examined. Litter substrate quality such as phyto-chemicals, microbial biomass, Lignin, Lignin N ratio, Lignin P Ratio, Tannins, Polyphenols, Cellulose, C:N ratio, C:P ratio, mineralization rate, duff and bulk densities were deliberated. Litter bag experiment was carried out to determine litter mass loss and mineralization rate. The experiment had two Seasonal Treatments, four vegetation treatment types and seven different distance treatments. Data collection involved measurements of photosynthetic active radiation, stomatal conductance, quantifying N and P in the sample, analysis of microbial biomass, Ectomycorrhizal, Arbuscular mycorrhizal, fungal biomass, leaf chemistry and root exudates. Data was summarized using excel package and then analyzed using Statistical Package for Social Sciences (SPSS) for window version 22. All the hypotheses were tested at α=0.05 and regression analysis made. The study results did not find much difference in the two exotic trees compared to Acacia in terms of changes in soil pH. The rate of decomposition and litter chemistry of the two exotic trees were different compared to Acacia. Likewise, the performance of adjacent pasture in terms of species composition, richness and cover also varied greatly. This was due to differentiated light quality in terms of Photosynthetic Active Radiation, soil porosity and competition for available Nitrogen. In addition, Competition for the available moisture is another considerable factor. Dense roots network was found to affect adjacent grass soil moisture in their root zone. Microbial biomass N, C and P was found to influence the rate of decomposition and release of nutrients to the soil. The study concludes that some of the valued exotic trees have potential of influencing negatively the adjacent crops/grasses if associated risks and benefits have not been studied well. The study recommends that any establishment of tree adjacent to crops or grasses, should consider tree species space requirement, potential spread of roots and contextual dependency relationship between N input pool and changes in soil properties
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    Efficacy of Moringa Oleifera and Moringa Stenopetala Leaves on Growth Performance, Haemato-Biochemical Profiles and Gut Microbiota in Broiler Chicken
    (KeMU, 2021-09) Nathaniel, Ebenezer Udofia
    Antibiotic growth promoters (AGP) have been used for decades to enhance production of meat, poultry growth acceleration, as well as improved disease prevention. The extensive use of antibiotics has led to development of resistant pathogens causing deleterious environmental and public health effects thus the need for antibiotic growth promoters for the poultry industry. The objective of this study was to assess the effectiveness of Moringa oleifera and Moringa stenopetala leaves on growth, blood and gut microbiota in broiler chicken. The study was carried out at the Mount Kenya University demonstration farm, Thika. Three hundred one-day-old mixed sex Cobb 500 broiler chicks from Kenchic Ltd, Kenya were used in a completely randomized block study design and twenty treatments used in the experiment. Maceration using aqueous and ethanol was used as the extraction method. The results were analysed using Minitab Version 19.1. First, a one-way analysis of variance (ANOVA) was used; thereafter, Fisher’s Least Significant Difference was used at 0.05 Level of significance. Results proved that powders from M. Stenopetala and M. oleifera are potent growth promoters. This was evidenced in the body weight gained by the chicks served with the feeds supplemented with graded levels of the studied powders. Similar result was obtained for the ethanolic and aqueous leaf extracts of the studied plants as growth promoters in terms of weight gains. The study showed that both plant leaves did not negatively affect the studied haematological parameters. Upon determination of the effects of the studied plant powders on the selected biochemical parameters, it was concluded that no adverse effects were exhibited. It was also concluded that the studied plant powders and the studied extracts influenced gut microbiota. It was further concluded that the treatment groups of chicken which received the leaf powders of M. oleifera and M. Stenopetala had significantly low total coliform counts (p<0.05).The study showed that the leaf powders of both M. oleifera and M. Stenopetala are endowed with a variety of important nutrients known to promote health in animals and humans. The results showed that the leaf powders of M. oleifera has significantly higher concentration of the assayed vitamins than those in the leaf powder of M. Stenopetala (p<0.05). The two plant powders possess pharmacologically important phytochemicals which are associated with proper growth, melioration of oxidative stress, antimicrobial activity, and immunomodulation as well as health promotion. M. oleifera leaf powder has significantly higher phenolic content than that of M. Stenopetala (p<0.05). From this study, the use of M. oleifera and M. Stenopetala leaf powders as alternative and safer broiler chicken feed supplements is encouraged. Studies geared towards further validation, authentication of the use of M. oleifera and M. Stenopetala in other poultry species are encouraged
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    Effects of Watering Regimes, Fertilizer Levels on Nutrients Uptake, Growth and Yield of Upland Rice in Mwea, Kenya
    (KeMU, 2020-11) Kirambia, Rosemary Karimi
    Upland rice contributes substantially to food and nutritional security in many African countries. Introduction of NERICA cultivars was meant to boost the production and hence area under upland rice. Factors such as poor soils and inadequate rainfall limit both the quality and achievement of yield targets. The research aimed to establish the impact of water levels, fertilizer rates on nutrients uptake and performance of NERICA 1 rice variety. It was carried out in a greenhouse setting in 2017 for two seasons and a field experiment at Kirogo farm at KALRO-Mwea. The treatments were; two water rates; 3.5 mm day-1 and 7.0 mm day-1; four rates of Phosphorus from Triple superphosphate applied at a ratio of 0, 20, 40, 60 kg ha-1 P2O5 and 4 rates of Potassium (K2O) at 0, 10, 20, 30 kg ha-1 applied as murate of potash. 60 kg ha-1 of N was applied in all treatments. Experimental set up was arranged in split plot layout replicated three times, whereby water levels were assigned in the main plot while fertilizer rate in sub-plot. Plant height, number of tillers and leaves, were growth parameters measured while yield components included weight of panicle, percentage of filled grains, weight of 100 dry grains, grain width/length ratio and overall grain yield ha-1. Details of nutrients uptake (NPK) in straw and crude protein in grain, and soil analysis were recorded. The data was subjected to F-Test at 5% significance level using SPSS version 23 and means separation done using LSD, DMRT and T-test. Water levels had significant effect at p= 0.05 on growth parameters, yield of crop and WUE. Maximum grain yield of 4,535.6 kg ha-1 and 2,705.1 kg ha-1was achieved with 7.0 mm day-1 in season one and two respectively while top most crop yield of 3,745.4 kg ha-1 was attained by P1K2 (0 kg ha-1 P2O5+0 kg ha-1 K2O) fertilizer level, being average of two seasons. In second season, fertilizer levels had significant effect (p= 0.05) on WUE with P1K2 (0 kg ha-1 P2O5+0 kg ha-1 K2O) giving highest value of 0.66.00 kg ha-1m-3,whereas P4K4 (60 kg ha-1P2O5+30 kg ha-1 K2O) gave lowest yield of 0.36 kg ha-1m-3, as an average for the two seasons. P3K3+W2 (40 kg ha-1 P2O5+20 kg ha-1 K2O -7.0 mm day-1 water fertilizer interaction had highest yields of 4,603.6 kg ha-1 whereas P4K4W1 had the least crop yield of 1,832.4 kg ha-1. Significant interaction effect (p= 0.05) was observed in water regimes and fertilizer rates on WUE in both seasons. Greatest WUE of 0.86 kg ha-1m-3 was achieved in the P1K2W1 (0 kg ha-1 P2O5+10 kg ha-1 K2O) interaction while the lowest (0.30 kg ha-1m-3) was attained by P4K4W2 (60 kg ha-1 P2O5 +30 kg ha-1 K2O+ 7.0 mmday-1). Percentage NPK uptake in straw and crude protein in grain increased with increase of P2O5 and K2O levels up to 20 kg ha-1 above which it dropped. For profit, efficient water use, and good performance of NERICA 1, use of P1K2 (0 kg ha-1 P2O5 + 10 kg ha-1 K2O) with 3.5 mm day-1 while for quality parameters, P2K2 (P2O5, 20 kg ha-1 and K2O -10 kg ha-1) plus 7.0 mm day-1 seems to be the sustainable choice for production of the variety in Kirogo –Mwea soils.