Browsing by Author "Gweyi, Joseph Onyango"

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    A Comparative Study of Plant Species Composition of Grasslands in Saiwa Swamp National Park and Kakamega Forest, Kenya
    (2010) Akwee, P.E.; Palapala, V.A.; Gweyi, Joseph Onyango
    Kakamega forest is a tropical rain forest ecosystem while Saiwa Swamp National Park (SSNP) is a riverine ecosystem. A study was conducted to determine plant species diversity of the grasslands in both the ecosystems with emphasis on herbs and grass species, and the structure of the ecotones. The objective of study was to compare the plant species richness of these two ecosystems with an aim of proposing some conservation strategies. Species diversity was determined using inverse Simpson Index. The sampling sites were determined using stratified random sampling. The random quadrats (1x1M), line intercept, and nested quadrat sampling methods were used to collect data from the clear grassland. A 5x5M sampling plot was used to collect data from the bushed-grassland community of both ecosystems. All plants species present were identified and recorded. The density, frequency, foliage cover, importance value indices and relative values were calculated. Temperature and relative humidity were determined. Results clearly show that Kakamega forest grassland community had the highest species diversity of 0.9 and an abrupt ecotone compared to Saiwa National Park of species diversity of 0.8 and a blending ecotones These results confirmed that, there is great variation in species diversity in both ecosystems and discontinuity of ecotones due to influence of environmental conditions.
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    Differential Benefits Of Rock Phosphate (RP) By Tomato ( Lycopersicon esculentum check for this species in other resources Mill.) Plant As Affected By Nitrogen Forms And Soil Types
    (Bioline International, 2010) Gweyi, Joseph Onyango; Günter, N.; Römheld, V.
    Phosphorus is one of the critical elements that limit plant production, particularly in humid and semi-humid soils. For realization of African Green Revolution, use of rock phosphate (RP) by resource-poor farmers may be an alternative to more expensive water soluble phosphate (P). Utilization of RP was investigated in tomato ( Lycopersicon esculentum check for this species in other resources Mill) var; Moneymaker in minirhizotrons at Hohenheim to assess root-induced chemical changes in the rhizosphere with two soil types: - Arenosol and C-horizon of Luvisol. Additionally, field experiments were conducted at Kibwezi and Maseno (Luvisol and Ferralsol, respectively) in Kenya. All trials received RP and soluble P as source of P and nitrate and ammonium (stabilized with DMPP as nitrification inhibitor) as nitrogen sources. Ammonium treatment significantly reduced rhizosphere pH in minirhizotron treatment with Arenosol with corresponding increase in shoot P content (but with significant negative shoot biomass accumulation), while rhizoplane pH differed significantly from rhizosphere pH treatment with C-horizon of Luvisol and there was no RP benefit to plant. The buffer capacity of the Luvisol was quite high and the pH 2mm away from rhizoplane was similar to that of bulk soil. However, minimal NO3- additions to ammonium treatment significantly improved biomass production in both soils. In both rhizobox experiments, NO3- led to rhizosphere alkalinization. Both shoot and fruit biomass was enhanced by RP application at Maseno, while RP had a negative effect on tomato plant production at Kibwezi. Therefore, role of RP on improved tomato yield at Maseno may partly be attributed to secondary factors other than P, viz; alleviation of aluminium rhizotoxicity since the Al content was significantly reduced by RP treatment, while RP may have led to partial alkalinization at specific root/rhizoplane, leading to Zinc deficiency at Kibwezi site. The application of rock phosphate in addition to acidifying nitrogenous fertilizer with consideration to soil types has potential of improving crop production and phosphate capital of resource-poor farmers.
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    Drought-Resilient Climate Smart Sorghum Varieties for Food and Industrial Use in Marginal Frontier Areas of Kenya
    (Kenya Agricultural and Livestock Research Organization, Industrial Crops Research Cente, 2022) Njinju, Symon M.; Gweyi, Joseph Onyango; Mayoli, Rose N.
    Sorghum bicolor (L) is classified globally as the fifth most important cereal crop after wheat, maize, rice, and barley. The demand for sorghum in Kenya is increasingly at 275,000 T per annum against the estimated production value of 150,000 T, providing income to more than 3 million people. Apart from food, Kenya Breweries Limited consistently provides a ready market to a huge amount of sorghum estimated at 60,000 tonnes annually and is expected to rise with time. In Kenya, the sorghum productivity level is at 0.7 t/ha in Arid and Semi-arid Lands areas (ASALs), which is far much below the potential yield ranging between 2 and 5 ton/ha. Sorghum’s rich diversity in ASAL areas makes it suitable for adaptability to Climate Smart Agriculture, Technologies Innovations Management Practices. This makes it a worthy crop for supporting livelihoods under the harsh climatic condition caused by climate change. In Kenya, Sorghum crop is usually cultivated at 0–2200 m above sea level in Eastern, Nyanza, and Coastal regions. Being a C4 plant, it has an efficient carbon dioxide fixation that makes it perform well in lower altitude areas with high temperatures, low, intermittent, and unreliable rainfall. Farmers in such areas opt to grow local varieties instead of the high-yielding hybrids due to poverty, inability to afford irrigation facilities, and essential necessities for production. Drought and water stress caused by inadequate and unevenly distributed rainfall in ASALs limit sorghum productivity. Also, pests, diseases, low yields, weeds, local planting seeds, and use of fertilizers are other challenges. On the other hand, enhancement of drought tolerance in arid climatic conditions involves
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    Effects of biochar and inorganic fertilizer on french beans (phaseolus vulgaris l) performance in nitisols
    (2014-08-01) Chege, Patrick Kamau; Gweyi, Joseph Onyango
    Use of biochar is a proven technology in crop production; however, scarcity of information of how it is utilized commercially has led to poor recommendations to local farmers. There is little research work on utilization of biochar in this country especially as it relates to legumes. The little that has been done focuses more on maize and generally on smallholder farmers. The field is still relatively new and not well understood. The goal of this study is to determine the effects of two types of biochars: carbonized chicken manure and carbonized cow dung manure with or without Mavuno fertilizer grade 15:10:18 on the performance and the chlorophyll content of French beans (Phaseolus vulgaris) variety slender green from Elgon Kenya. The effects of the two types of manures on French bean will be documented for comparison. The treatments will be replicated three times and will be set on a completely randomized block design. The experiment will be conducted in an open field at Kenya Agricultural Research Institute (KARl) Thika station. The study will be conducted in 2014 long rain season and repeated during the short rains. Data will be collected on plant height, number of leaves, pod weight, leaf area, the chlorophyll content and biomass of this legume. The collected data will be analysed through the analysis of variance (ANOVA) while means will be separated using least significant difference (LSD). Biochar is known to have an ameliorating effect on various soil properties such as improvement of water holding capacity, nutrient retention and liming effect. Soil samples will be taken before planting and after harvest and will be analyzed to determine the effects of biochar on soil properties. The effects of biochar on the level of phosphorous, calcium and magnesium content of the soil and the performance and chlorophyll content of French beans will be determined and documented. Key words: carbonized chicken manure, carbonized cow dung manure, yield, growth parameters, French beans, Mavuno fertilizer 15:10:18 chicken manure and cow dung manure.
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    Genotypic Responses of Cowpea (Vigna unguiculata) to Sub-Optimal Phosphorus Supply in Alfsols of Western Kenya: A Comparative Analysis of Legumes
    (2011) Gweyi, Joseph Onyango; Akwee, Peter; Onyango, Christine; Tsehaye, Tesfamariam
    Western parts of Kenya are characterized by acid soils with phosphorus [P] deficiency and aluminum [Al] phytotoxicity. Reports indicate a declining trend in yields of legumes such as cowpeas. Though legumes can fix N, starter phosphorus need to be supplied for better yields and more often plants develop adaptive strategies for better P acquisition; probably through increased Al tolerance by carboxylates exudation, improved nodulation as a result of high P and better root development. Present study examined mutual relationship between P and nodulation in explaining yield differences between Cowpea (Vigna unguiculata) varieties: Elanda (ELn, high yielding) and Inzeku (INz; moderate yielding), Ground nut (Arachis hypogea)-GN and Bambara nuts (Vigna subterrenea (Verdc) - BBN with proven P efficiency and Bean (Phaseolus vulgaris L) varieties Rosecoco (RCC) and Edwin (ED); low P efficient formed basis for comparison. The experiment was conducted at Masinde Muliro University field station from April 2009 and experimental design was CRBD having split plot with P as main plots (+P; or –P), whereas GN, BBN, ELn, INz, RCC and ED legumes were randomized within the P treatments. Legume genotypes were replicated four times. There were no differences in shoot biomass with +P and –P (INz), but ELn showed higher shoot DM with +P as compared with –P (significant p<0.05). Similar trends were replicated with nodulation with P supply. Shoot DM and nodulation were positively correlated for ELn (r2=0.99; +P and r2=0.68; -P) but not INz. Correlations were negative for beans and performance of BBN with +P and –P showed trends similar with Inz genotype. Sub-optimal P supply with concomitant enhancing nodulation in INz could not explain genotypic differences in yields, since high yielding BBN lacked this trait with additional P. Factors like high proton concentration and Al saturation need to be assessed and likely an interaction between P and Al through enhanced exudation of carboxylates may give more insights to cowpea genotypic differences.
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    A Rapid Hydroponic Screening of Field and Horticultural and Crops for Aluminium Tolerance
    (2011) Makau, M; Masito, S.S.; Gweyi, Joseph Onyango
    Aluminium toxicity is a major crop production constraint, particularly in acid tropical soils. The toxicity is aggravated when pH falls below 5.5 since toxic monomeric Al species get solubilized. The screening of Al tolerance intrinsically depends on culture medium, with a nutrient solution having pH of 4.5 being recommended. Hydroponic experiment was carried out at Jomo Kenyatta University of Agriculture and Technology in February 2010 to investigate maize (Zea mays), garden pea (Pisum sativum), bean (Phaseolus vulgaris L) and cucumber (Cucumis sativus) tolerance to elevated Al in the rhizosphere during the early plant growth stages. We hypothesized existence of genotypic differences in tolerance to Al stress. The above plants constituted the main plots and subplots consisted of 3 levels of monomeric aluminium species (0, 50 and 100M) supplied as AlCl3. The plants were cultivated for 7d in full strength solution after transplant from peat/perlite mixture. On application of Al, the pH of the incubation medium was adjusted to 4.5. Based on morphological differences, putative aluminium resistant crop genotypes were identified. Increasing Al concentration to 100M significantly affected root elongation rates, shoot DM, root DM and root/shoot ratios of cucumber, bean and garden pea but marginally affecting maize and the trend was same for root/shoot ratio. The 50M Al supply did not seem to have clear inhibitive effect as expected and in some instances eliciting promotive growth. The experiment reveals genotypic variation in plant genotypes in Al tolerance that can be exploited for target breeding in acid soils. The root elongation was the single most significant index in ranking the genotypes against Al tolerance. We also conclude that simple nutrient solution can be effectively used for screening crops for Al tolerance.
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    Safe vegetable production with wastewater in developing countries: demystifying the negative notions
    (2011-12) Gweyi, Joseph Onyango; Osei-Kwarteng M.
    The unplanned shift from rural to urban cities in developing countries have continually put burden on planners, policy makers and the residents. The productive use of wastewater has increased alongside increased rural-urban shift, as millions of small-scale farmers in urban and peri-urban areas of developing countries increasingly depend on wastewater sources to irrigate high-value edible crops for urban markets. Despite the good motive, undesirable constituents in wastewater can harm human health and the environment. The heavy metals such as Lead, Chromium, Zinc, Nickel and Cadmium have been detected in vegetables and may get biomagnified in food chain if the contaminated irrigated products are continually consumed. This can be fatal in the long run. There has been brewing unspoken skeptism regarding the vegetable products derived through this avenue. Apart from the consumers, government agencies in horticultural industries and those involved in quality standard regulations have, through design or default, failed to offer support to farmers’ initiative and resolve to safely utilize wastewater for vegetable production. In this paper we review the key initiatives and compelling reasons that motivate farmers to utilize the wastewater; health risks not withstanding. The review dissects an array of crop choice interventions that lead to soil health mitigation with minimal human health implications. We single out and place emphasis on vegetable crops with hyperaccumulator traits for the purpose of soil remediation, but with a higher biomass as this leads to metal dilution within the plant. We also give a distilled analysis on the policy and social-cultural implications in regard to wastewater use and further appreciate the challenges the policy makers face in attempt to implement the blueprint on wastewater use.