Department of Plant Science

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Heavy Metal Phytoremediation Potential of Wild Plant Species Naturally Growing on Dumpsite, Kenya
(chuka university, 2024-12-04) Orao LA1 , Muraya MM2 and Ombaka CO3; ; ;
Soils form an essential part of life and the main sink of pollutants. Intense industrial and anthropogenic activities have led to serious environmental threats, resulting in increased heavy metal concentration in soils and, consequently, a phytotoxicity effect on plants. Phytoremediation can offer effective and eco-friendly remedies for polluted sites. This study characterized the diversity of various plants that spontaneously grow in a dumpsite and scrutinized their phytoremediation potential. The plants evaluated for phytoremediation potential were Ricinus communis, Parthenium hysterophorus, Cassia didymobotrya, and Datura stramonium. The location of the research was Kang’oki dumpsite, Kenya. Species diversity was studied using quadrat sampling thrown randomly throughout the dump site. The bioaccumulation factor (BF) and the translocation factor (TF) were calculated to determine the accumulation and mobility of the heavy metals in the plants. To determine the ability of the plants to remove, accumulate, and mobilize the selected heavy metals, soil and plant sampling was conducted within the 14 sampling sites. The samples were acid-digested, and concentrations of Pb, Zn, Cu, and Cd were analyzed using Atomic Absorption spectrophotometry. Data obtained was subjected to statistical analysis using SAS version 94. Shannon-Weaver diversity index (H’) was used for species diversity. An H’ of 0.94 and species evenness of 0.45 was found showing a high species diversity on the dumpsite. Cadmium concentration in soil samples ranged from ND to 1.63 mg/kg of soils and 0.4418 to 0.6939 mg/kg of plant tissues. Nickel concentration ranged from 7.9 to 36.33 mg/kg in soils and 9.31 to 11.38 mg/kg in plant tissue, respectively. Copper was found between 3.41 to 121.18 mg/kg of soils and 3.74 to 10.89 mg/kg of plant tissues, respectively. Lead in soils ranged from 13.25 to 8.013 mg/kg of soils and 11.48 to 13.89 of plant tissues. Leaves accumulated significantly (p < 0.05) higher amounts of heavy metals than roots and stems. The leaves and stem of Datura stramonium showed the highest concentration of cadmium and copper, while its stem showed the maximum concentration of Nickel and lead. Datura stramonium showed BCF and TF >1; hence, it can be used for phytoextraction of cadmium. All plants showed TF>1; hence, these plants can be used as hyperaccumulators.
Optimization of Groundnuts (Archis hypogeal) Yield through Response Surface Methodology
(Asian Journal of Probability and Statistic, 2024-04-10) Dennis Kiprotich a,b* , Dennis K. Muriithi a,b and Martin K. Njogu a,; ; ;
Groundnut production faces several constraints, including poor soil fertility, small land sizes, and inappropriate agricultural techniques. The study aimed to optimize groundnut (Archis hypogeal) yield using response surface methodology (RSM). It explored the use of CCD and RSM to determine the optimal application of rabbit, poultry, and sheep manure for maximum yield, a method not previously applied in groundnut production. The study was conducted at the Chuka University Teaching and Training Farm, Kairani. The experimental design was developed using Central Composite Design (CCD), with 20 experimental runs derived from 2 3 full factorial designs with six axial points and six center points. Data was collected on the weight of the groundnuts yield harvested in each experimental plot measured by use of a weighing scale. Response Surface Methodology techniques was adopted for data analysis in R-statistical software and R studio programing language. The study findings indicated that organic manures had a significant effect (P < 0.05) on the yield of groundnuts crop. The study revealed that application of 13.6097 t ha-1, 10.582 t ha-1 and 11.0814 t ha-1 of poultry, rabbit and sheep manure respectively are the optimum levels that would lead to maximum weight of groundnuts in the study area. The finding of this study could have an economic benefit to farmers in the study area which aligns with broader national goals of poverty reduction, rural development, and economic growth. This study recommended that farmers should adopt organic farming practices to reduce reliance on chemical fertilizers, improve soil health, and contribute to environmental sustainability.
Analysis of Technical Efficiency on Orange Fleshed Sweet Potatoes Production Among the Smallholder Farmers in Migori County Kenya
(Scvience of PG, 2024-10-18) Lawrence Otieno Jabuya1, * , Shelmith Wanja Munyiri2 , Martin Kagiki Njogu2; ; ;
Sweet potatoes (Ipomea batatas L.), particularly the orange fleshed variety, have become increasingly popular due to their ability to thrive in various environmental conditions with minimal inputs. Orange fleshed sweet potatoes (OFSPs) show potential for productivity, yet smallholder farmers in Kenya still struggle to maximize their yields. The factors influencing OFSP production efficiency among these farmers in Western Kenya have not been thoroughly examined. This study evaluated the technical efficiency of OFSP production among smallholder farmers in Migori County. Using a descriptive research design, a sample of 225 OFSP farmers was randomly selected by a cluster sampling technique. Data was collected through a structured questionnaire on inputs and selected socio-economic factors. The data was analyzed using the frontier stochastic model in STATA. Smallholder farmers estimated mean technical efficiency was 77.82% significant variables were; size of the land, availability of planting vines, access to hired labour, gender of the household decision maker, farming experience, household size, land ownership status, participation in training programs and extension services, and proximity to markets, indicating a need to improve OFSP production by 22.18%. These findings suggest that to reduce inefficiencies among smallholder OFSP farmers, targeted training programs are needed to enhance farmers' agronomic knowledge specific to OFSP production. Further, policy interventions should prioritize the provision of extension services to support and improve the performance of OFSP smallholder farmers.
Production of Mineral Nutrient-Rich Multipurpose Pumpkin Leafy Vegetables Using Integrated Nitrogen, Mulch and Ga3
(Journal of Environmental Sustainability Advancement Research, 2022) Mwaura, M. M., Isutsa, D. K. and Munyiri, S. W.; ; ;
Understanding the effect of nitrogen, mulch and gibberellic acid on minerals and metabolites in multipurpose pumpkin (Cucurbita moschata Duch) is important since it is a dependable source of food, providing families producing it with various diets that contribute to household food and nutrition security. However, production of the pumpkin using optimal or integrated inputs has not yet been embraced in most African countries, resulting in underrealization of its maximum potential. To respond to this challenge, a split-split plot experiment arranged in randomized complete block design and replicated three times was conducted for two seasons from January 2019 to July 2020. The nitrogen (0, 50, 100 and 150 kg N/ha) was assigned to main plots, mulch (no mulch, black-painted and unpainted rice straws) to sub-plots, and gibberellic acid (GA3) (0 mg/L, 40 mg/L and 80 mg/L) to split-plots. Nitrogen was applied as calcium ammonium nitrate (CAN) in two equal doses for each rate at three weeks postemergence and at the beginning of flowering. The black-painted and unpainted rice straws were placed on plots after land preparation. The GA3 solution was sprayed to plants using a 1-L sprayer, starting with 40 mg/L, followed by 80 mg/L, once during the fourth week post-emergence. Data collection was done fortnightly from the fourth week after emergence up to fruit harvest stage. Data values were subjected to analysis of variance using SAS software version 9.3 and means separated using the least significant difference test at α=0.05. All the measured parameters were significantly (P<0.05) different. Highest levels of K and Mg were obtained for 100 kg N/ha. On the other hand, P and beta-carotene were highest where unpainted rice straws were used, while application of 80 mg/L GA3 yielded high amounts of P and K. Results further showed that combined N fertilizer, mulch and GA3 consistently had significant (P<0.05) effects on N, P, K, Mg and beta-carotene (highest 23 ppm was for N1M1GA1). Therefore, sole nitrogen fertilizer, mulch, GA3, and combined rates that promote the desired mineral nutrient and beta-carotene contents in multi-purpose pumpkin leaves should be adopted and applied, depending on the kind.
A Comparative Study of Caffeine Levels in Coffee and Cocoa in Kenyan Supermarkets and Shops
(Pan-African Journal of Health and Environmental Science, 2024-05-20) Alex Muthengi1*, Silas Njiru1 and Juster Mungiria; ; ;
Background: Caffeine is an alkaloid belonging to the methylxanthine family. An overdose of caffeine causes the following side effects: restlessness, nervousness, excitement, insomnia, flushed face, diuresis, gastrointestinal disturbances, muscle twitching, rambling flow of thought and speech, and tachycardia or cardiac arrhythmia. This study aimed to determine the caffeine levels of various brands of coffee and cocoa and enlighten people on the safe and healthy consumption of the two products. Methods: Different brands of coffee and cocoa products were randomly sampled and purchased from supermarkets and shops in Nairobi, Kenya. Five samples of coffee and four brands of cocoa were purchased from a supermarket and taken to the laboratory for analysis. Caffeine was extracted, and quantitative analysis was done using High Performance Liquid Chromatography (HPLC). Results: The study found that coffee has a higher concentration of caffeine than cocoa. Coffee Brand A recorded the lowest level of caffeine with 30.9845 µ g/g, while Coffee Brand C recorded the highest level of caffeine with 426.9639 µ g/g. Among the Cocoa brands, Cocoa Brand B recorded the lowest level of caffeine (2.6367 µg/g), while Cocoa Brand C recorded the highest level of caffeine at 19.03 µ g/g. Conclusion: Therefore, there is a need to reduce coffee consumption per day because caffeine overdose can cause high blood pressure and other illnesses. Cocoa is recommended for consumption since it contains less caffeine per servin
Optimization of Groundnuts (Archis hypogeal) Yield through Response Surface Methodology
(Asian Journal of Probability and Statistic, 2024-04-10) Dennis Kiprotich a,b* , Dennis K. Muriithi a,b and Martin K. Njogu; ; ;
Groundnut production faces several constraints, including poor soil fertility, small land sizes, and inappropriate agricultural techniques. The study aimed to optimize groundnut (Archis hypogeal) yield using response surface methodology (RSM). It explored the use of CCD and RSM to determine the optimal application of rabbit, poultry, and sheep manure for maximum yield, a method not previously applied in groundnut production. The study was conducted at the Chuka University Teaching and Training Farm, Kairani. The experimental design was developed using Central Composite Design (CCD), with 20 experimental runs derived from 2 3 full factorial designs with six axial points and six center points. Data was collected on the weight of the groundnuts yield harvested in each experimental plot measured by use of a weighing scale. Response Surface Methodology techniques was adopted for data analysis in R-statistical software and R studio programing language. The study findings indicated that organic manures had a significant effect (P < 0.05) on the yield of groundnuts crop. The study revealed that application of 13.6097 t ha-1, 10.582 t ha-1 and 11.0814 t ha-1 of poultry, rabbit and sheep manure respectively are the optimum levels that would lead to maximum weight of groundnuts in the study area. The finding of this study could have an economic benefit to farmers in the study area which aligns with broader national goals of poverty reduction, rural development, and economic growth. This study recommended that farmers should adopt organic farming practices to reduce reliance on chemical fertilizers, improve soil health, and contribute to environmental sustainability
Effects of Earthing up and Pruning Systems on Post-Harvest Quality of Tomato (Solanum lycopersicon)
(International Journal of Plant & Soil Science, 2022-11-21) Keter, I. K.; G. O. Oloo-Abucheli; M. Muraya; C. T. Kiplangat; ; ;
Tomato is a popular and extensively cultivated vegetable among the economically promising commodities in the horticulture sector in Kenya. It provides a wide variety of nutrients with many health-related benefits. This study investigated the effect of integration of pruning and earthing up on postharvest. The experiments were carried out in a split-plot arranged in a randomized complete block design (RCBD) and in CRD for both field and laboratory work respectively. Fruit yield data was taken after each harvest. The results from the analysis of variance for the effect of factors (earthing up and pruning system) and their combined effect showed that there was a significant effect on the average weight loss percentage and total soluble solids in both cultivations. The treatments had a significant effect on the average weight loss percentage, total soluble solids, and fruit firmness in both cultivations. The highest fruit weight loss percentages were recorded from all stem pruning system with no earthing up. The highest fruit firmness (3.41 N mm-1 in cultivation 1 and 3.24 N mm-1 in cultivation 2) was recorded from a single stem pruning system and earthing up to 30 cm. The highest total soluble solids (TSS) percentage 6.09 % was recorded in both cultivations under a single stem pruning system and earthing up to 30 cm. To improve tomato postharvest, farmers are encouraged to consider triple stem pruning system in combination with earthing up to level 30 cm.
Modelling Nutrient Dynamics and Maize Yield sunder Different Cropping Systems and Organic Amendments Using APSI Min Central Kenya
(Chuka University, 2018-09-20) Ndukhu, O.H.,Wahome,G.R.; ; ;
A simulation study was carried out using APSIM model to assess the maize yield and soil nutrients to changes in temperatures and rainfall in Kabete and Kiserian areas of central Kenya. To obtain data for model calibration and validation, on-station (Kabete) and on-farm experiments (Kiserian) were set out during the short rain season of 2013. The experimental design was a randomized complete block (RCBD) with a split-plot arrangement where the main plots were three cropping systems; monocropping, intercropping and crop rotation and the split plots were farmyard manure (FYM) and Minjingu Rock Phosphate (MRP), and a control. The effect of the changesin rainfalland temperature on maize yields was considered, i.e. current temperature combinations in accordance to the International Panel on Climate Change projections.The model performed better for Kabete (ME=0.6) than Kiserian (ME=0.9). Simulations of crop rotations correlated most (R2=0.48) with observed results at Kabete and Kiserian. Simulations of the intercrops correlated favourable with coefficientofdetermination(R2)valuesof>0.4showingareasonablerelationshipbetweenobserved and simulated values. However, mono-crop simulation varied highly from observed yields (R2<0.3). TheAPSIMsimulatedmatched well withtheobserveddata in thetrial;rootmeansstandarderror
Evaluation of cardiopreventive efects of Ximenia americana (Linn.) and Pappea capensis (Eckl. and Zeyh.) leaf aqueous extracts in rat models with myocardial infarction
(Future Journal of Pharmaceutical Sciences, 2023-06-15) Daniel Muthee Gaichu1,3* , Patricia Mathabe2 and Mathew Piero Ngugi; ; ;
Background Myocardial infarction is a signifcant health issue in both wealthy and underdeveloped nations. Globally, it is the leading cause of deaths among cardiovascular diseases. In 2012, myocardial infarction-related deaths were about 14.1 million out of 17.5 million cardiovascular disease-related deaths. Clinical management of myocardial infarction remains a challenge because most conventional drugs provide symptomatic relief only. In addition, conventional remedies are associated with numerous advese efects and arguably, in many cases are quite expensive. Hence, herbal remedies, which are widely available, with comparatively fewer side efects, and are afordable, provide a more attractive therapeutic alternative. This study aimed at determining cardiopreventive efects of aqueous leaf extracts of X. americana and P. capensis. Phytochemical screening was done using liquid chromatography-mass spectrometry. Wistar albino rats were employed to test for cardiopreventive efects of the extracts and were randomized into 6 groups of 5 animals each. Groups I, II, and III were normal, negative, and positive controls, respectively, and rats were given normal saline, salbutamol (7.5 mg/Kg bw), and propranolol, respectively. Groups IV, V, and VI rats were treated with extracts dose levels 50, 100, and 150 mg/Kg bw, respectively. Biochemical analysis was done to determine efects of the extracts on levels of serum cardiac troponin T, creatine kinase-MB, lactate dehydrogenase-1, and lipid profles. Levels of oxidative stress markers were determined in the heart tissue. Results The LC–MS analysis revealed diferent phytocompounds in the extracts, including favonoids, phenolic acids, glycosides and tannins, which are known to confer cardioprotective activities. The extracts signifcantly prevented increase in cardiac troponin T, creatine kinase-MB, lactate dehydrogenase-1, total cholesterol, triglycerides, LDL, and MDA levels, as well as a signifcant increase in superoxide dismutase, catalase, glutathione peroxidase, and HDL levels. Conclusions This study confrmed that Ximenia americana and Pappea capensis extracts have the potential to prevent myocardial infarction in rats. Generally, P. capensis extract showed better activity as compared to X. americana extract. The efects of the extracts could be attributable to the presence of various cardioactive phytocompounds. Therefore, these plants can be considered in the development of potent and safe cardiopreventive drugs.
Relationships of Selected Endogenous Factors Associated with Direct Somatic Embryogenesis of Coffee (Coffea arabica L.)
(Journal of Advances In Agriculture, 2018-05-30) Mayoli, R.N.; Isutsa, D.K.; Nyende, A.B.; Mweu, C.M.; ; ;
Coffee is one of the most important cash crops produced in the world with great economic returns to growers and national gross domestic product. Somatic embryogenesis is a morphogenetic processes leading to plantlet regeneration and these processes are coupled with changes in the levels of primary metabolites. The present experiment established relationships of endogenous substances with direct somatic embryogenesis of coffee ‘Ruiru 11’. Laboratory experiments were set up at Coffee Research Institute, Ruiru-Kenya between 2014 and 2017. The set up was in a completely randomised design, replicated three times and repeated once. Third leaf pair explants were excised from 8-month-old greenhouse-grown mother plants and cultured in half strength Murashige and Skoog basal salts augmented with Thidiazuron. Once embryos had developed, the cultures were analysed for endogenous substances using HPLC and GCMS. Sucrose, phenolics, alkaloids, amino acids, fatty acids and their derivatives correlated positively, whereas fructose and glucose correlated negatively with the other biochemical components.Endogenous sucrose, chlorogenic acid, caffeine amino acid, fatty acids and their derivatives are potential biomarkers for coffee somatic embryogenesis, whereas endogenous fructose and glucose are inhibitors of the same. Further studies regarding the status of the biochemical components, especially in particular stages of embryo development should be conducted to establish treatments that can improve coffee direct somatic embryo development.
Effect of Rainfall and Temperature Variability on Green Gram Yield in Tharaka South Sub County, Tharaka Nithi County, Kenya
(International Journal of Environment and Climate Change, 2023-05-26) Mathenge Beatrice Mugure a* , Gathungu Geofrey Kingori b and Dennis K. Muriithi c; ; ;
Globally, green gram is a significant legume particularly in Arid and Semiarid Lands (ASALs), as a source of food, income, and soil enhancement. Despite this importance, green gram yield in Tharaka South Sub County is still too low at 560 kg/ha far below the crop’s estimated national potential of 1500 kg/ha and compares unfavorably with the global and national average of 730 kg/ha and 670 kg/ha, respectively. Green gram production is primarily rain-fed and variability in rainfall and temperature affects the ideal conditions favourable for the crop growth. This study aimed at quantifying the effect of rainfall and temperature variability, separately and jointly on green gram yield in Tharaka South Sub County, Tharaka Nithi County, Kenya for the period 2002-2021. Secondary data on seasonal rainfall, temperature, and green gram yield was collected from the Meteorological Services and County Department of Agriculture. Data was analysed using qualitative and quantitative methods by use of coefficient of determination, Analysis of Variance (ANOVA), correlation, and regression analysis. The study found that rainfall variability explained 30.4% of the variables affecting green gram yield. The findings of the model showed that a 1% increase in rainfall in March-April- May (MAM) season increased yield of green gram by 49.3% but no effect was observed in OND (October-November-December) season. Temperature variability explained 28.5% of the variables affecting green gram yield. Further, the model findings revealed that a 1% increase in temperature in OND season decreased yield of green gram by 48.5% and no effect was observed in MAM season. A combination of rainfall and temperature variability explained 34.2% of the variables affecting green gram yield. The model coefficients showed that a 1% increase in rainfall and temperature during the OND season increased yield of green gram by 16.2%. In addition, it was noted that a 1% rise in temperature and rainfall during MAM season reduced the output of green gram by 13.2%. The study concluded that rainfall and temperature had an effect on green gram yield and recommended that green gram farmers need to adapt to the changing climate to lessen the effects of climate change and for sustainable green gram production.
Pesticides’ use and their management practices among farmers in Mutarakwa division of Bomet county, Kenya
(International Journal of Agriculture and Environmental Research, 2017-05) Njeru, Moses Kathuri; ; ;
The demand for food has increased tremendously over the years as the population grows. To meet this high demand for food, intensified agriculture has been prioritised. However, the resulting high crops yields are threatened by incidences of pests and diseases either at growing stage or at storage. To counter the loss associated with pests and diseases, the development and intensified use of pesticides has become imperative. This paper examines pesticides management practices in Mutatarakwa division in Bomet County, Kenya.
Effect of Source and Rate of Livestock Manure On Yield, Qualityand Net Economic Benefit of Okra (Abelmoschus Esculentus (L.) Moench.)
(Journal of Experimental Agriculture International, 2023-05-26) Kamunyu Deborah Ncuuri a*, Gathungu Geofrey Kingori a and Muraya Moses Mahugu; ; ;
Okra farmers use inorganic fertilizers which are expensive, they result to water pollution, increases the soil acidity, which affects soil nutrients availability and uptake as well as reducing microbial activity. Organic manure improves soil physical, chemical and biological properties, and are environmental friendly. However, farmers have limited information on the utilization of these organic manure sources on growth yield, quality and net economic benefit of okra. A study was conducted to determine the effects of rate cattle, goat and poultry manure on okra growth, yield, quality and net economic benefit at KALRO-Kandara Centre in Murang’a County between 2018 and 2019. The experiment was laid out in randomized complete block design with three replications for two cultivations. There were 10 treatments, i.e., 0, 3, 6 and 7 tonne ha-1 for cattle and goat manure, and 0, 3, 5 and 7 tonnes ha-1 poultry manure that were applied before planting okra variety Pusa Sawani. Data collected included yield characteristics total fresh pod yield and quality characteristics mainly total soluble solids (TSS). Data collected was subjected to analysis of variance using SAS statistical software version 9.4 and significantly different means were separated using LSD at α = 0.05. The results showed that there was significant effect of treatments (p < 0.05) on yield, quality and net economic benefit of okra. Poultry manure at the rate of 5t ha-1 recorded highest yield while control had the least. Goat manure at the rate of 6 tonnes ha-1 recorded the highest total soluble solids, hence, produced pods of the highest quality of 3.18°Brix and 3.21°Brix for Trial 1 and Trial 2, respectively, whereas the control produced pods of lowest quality of 2.31°Brix and 2.34°Brix for Trial 1 and Trial 2, respectively. Cattle manure at the rate of 6 tonnes ha-1 recorded the best net economic benefit of Ksh. 700,267 in Trial 1 and Ksh. 694,320 in Trial 2, while the control gave minimal returns of Ksh. 69,158 in Trial 1 and Ksh. 64,320 in Trial 2. This indicates an increase of net economic benefit of Ksh. 631,109 in Trial 1 and Ksh. 630,000 in Trial 2 for cattle manure compared to the control. The results of this study clearly indicate that in okra production, application of different types of animal organic manure can improve the productivity of the okra. The study recommends application of 5 tonnes ha-1 poultry manure, or 6 tonnes ha-1 of goat or cattle manure for best growth, yield, quality and net economic benefit of okra
Application of Central Composite Design Based Response Surface Methodology in Parameter Optimization of Watermelon Fruit Weight Using Organic Manure
(American Journal of Theoretical and Applied Statistics, 2017-03-18) Muriithi, Dennis K.; Koskei, J. K. Arap; Gathungu,Geofrey; ; ;
Response Surface Methodology (RSM) is a critical technology in developing new processes, optimizing their performance and improving the design. In Kenya, watermelon cultivation is gradually gaining ground. It is a crop with huge economic importance to man as well as highly nutritious, sweet and thirst- quenching. In order to increase crop production, there is need to increase soil nutrient content with organic manure such as poultry, cow or other animal wastes. At present, there are no recommended standards with respect to rate of poultry manure, cow manure and goat manure for enhancement of yield of watermelon in Kenya. The main objective of the study was to develop an approach for better understanding of the relationship between variables and response for optimum operating settings for maximum yield of watermelon crop using Central Composite Design and Response Surface Methodology. Response Surface Model evolved for response shown the effect of each input parameter and its interaction with other parameters, depicting the trend of response. Verification of the Fitness of the model using ANOVA technique shows that the model can be used with confidence level of 0.95, for watermelon production. Further validation of the model done with the additional experimental data collected demonstrates that the model have high reliability for adoption within the chosen range of parameters. The optimal value for each factor was found as 17.13tons/Ha of poultry manure, 13.3tons/Ha of cow manure and 18.1tons/Ha of goat manure. At optimal conditions, the actual value of the fruit weight of watermelon was 93.148tons/Ha. This translates to 37.3tons per acre piece of land of watermelon fruit weight for a period of 75-85 days after sowing. In addition, a peasant farmer can generate about 745,184 Kenya shillings within a period of 75 day in one acre piece of land at a low price of Kshs 20 per kilogram of watermelon fruit. RSM has resulted in saving of considerable amount of time and money hence recommended in similar study.
Effect of Harvesting Stage on Cowpea Leaf Nutrient Composition
(science publishing grouo, 2023-06-20) Gitau Jane Wanjiku*, Gathungu Geofrey Kingori, Kiramana James Kirimi; ; ;
Abstract: Cowpea leaves are enjoyed as vegetables in many parts of Africa as they contain a lot of antioxidants, micronutrients and nutraceuticals whose deficiency is prevalent among people in Sub-Saharan Africa. Cowpea leaves undergo several physiological and metabolic changes during their maturity stages which may affect their nutritional content. However, farmers lack knowledge on the best cowpea harvesting stage. This research therefore aimed at obtaining information on the right harvesting stage that would enhance cowpea utilization by farmers. Cowpeas variety M66 was planted in RCBD and the treatments which were replicated thrice included harvesting at 21, 35 and 49 DAS. Data was collected on chlorophyll content, iron, calcium, crude fibre, beta carotene, protein and moisture content. The data was subjected for variance using Statistical Analysis System 9.2 edition and significantly different means separated using LSD at 5%. The harvesting stage significantly (p ≤ 0.05) influenced the chlorophyll content with 49 DAS recording the highest content at 51.39 nm followed by 35 DAS with 41.87 nm and the least at 21 DAS with 22. 05 nm. The moisture content decreased with the stage of harvest with highest moisture content being observed at 21 DAS and the least at 49 DAS in both trials. The iron content of cowpea leaves was significantly (p ≤ 0.05) different at 49 DAS in both trials. The calcium content at 21 and 49 DAS in both trials was significantly (p ≤ 0.05) different. The protein content was significant (p ≤ 0.05) in all the stages of harvesting with the highest protein content in both trials being recorded at 21 DAS and the least being recorded at 49 DAS in both. Crude fibre content increased with the stage of harvesting in both trials. This research highlights the essence of harvesting cowpea leaves at the correct harvest stage for increased nutrient utilization.
Bio control mechanism of endophytic beauveria bassiana in three tomato (lycopersum esculentum) varieties
(Chuka University, 2018-06) Omukoko,C. A.; ; ;
Beauveria bassiana has gained considerable attention as biological control agent for most agricultural pests, however environmental variability has affected its efficacy and persistence. There is need to improve the delivery mechanism for B. bassiana, such as it’s use as an endophyte for protection from harsh environmental conditions. Endophytic fungi vary in their mode of action for insect and disease control. A clear understanding of the mode of action involved in biological control of Tetranychus evansi by endophytic Beauveria bassiana is important for successful application in the field. B. bassiana is known to synthesize hydrolytic enzymes such as lipase and protease which assist in degrading of the insect cuticle components. B. bassiana isolate IC 35 colonized tomato varieties Cal J, Kilele and Anna F1 in the screen house. The objective of this study was to determine the production of extracellular enzymes such as lipase and protease by endophytic B. bassiana isolate IC 35 on solid medium. To test the production of lipases, endophytic B. bassiana IC 35 from the three tomato varieties was grown for a-week on Sabourand Dextrose Agar and point inoculated on medium containing sorbitan monolaurate. To assess the protease activity, IC 35 was point inoculated on gelatin medium. The control plates lacked enzyme– specific substrates. All petri dishes were incubated for one week under laboratory conditions of 270c and 70% Relative Humidity. The diameters of the clear zone of inhibition and of fungal colonies were measured. Control plates had no clear zone since no enzymes were produced in them. Maximum lipase value of 2.15 cm and protease values of 2.2 cm activities were recorded on day 5 and there were significant difference among the tomato varieties for the treatments and control. These enzymes are important since they correspond to the main chemical integuments of the insect body, hence assist in breaking it down for effective biological control.
Enhancing preharvest physiology of multi-purpose pumpkin using combined nitrogen, mulch and gibberellic acid
(African Journal of Horticultural Science, 2022-03) Isutsa, D. K.; Mwaura, M. M.; ; ;
In recent times, it has become apparent that multi-purpose pumpkin (Cucurbita moschata Duch.) is a very important crop since its leaves, fruits and seeds can be eaten as vegetables, snacks and blended dishes to boost household food and nutritional security. However, it is regarded as a low value crop, leading to poor cultivation, comprehension of preharvest physiological behaviour, and maximization of productivity in Kenya. Consequently, a study was conducted to assess the effects of combined nitrogen, mulch and gibberellic acid (GA3) in enhancing its preharvest physiology of pumpkin. Four N rates of 0, 50, 100 and 150 kg N/ha supplied as CAN, three mulch types as none, unpainted, and black-painted rice straw, and three GA3 rates of 0, 40 and 80 mg/L were assessed. The experiment was arranged in split-split plots in randomized complete block design, replicated three times in two seasons, and each plant occupied 2 m x 2 m space. Nitrogen was applied to main plots, mulch to sub-plots, and GA3 to sub-sub plots. Pre-harvest physiological variables measured were stomatal conductance, chlorophyll, photosynthesis, and transpiration. Data values were subjected to analysis of variance using SAS Version 9.3. Separation of significant means was done using the least significant difference test at α = 0.05. Results showed that nitrogen and mulch individually and interactively did not significantly (P > 0.05) affect most pre- harvest physiological parameters. The effect of GA3 was not significant on stomatal conductance and leaf chlorophyll, but it was negative and significant on both photosynthesis and transpiration in season 1 which was drier than season 2. Based on the present results, the influence of combined nitrogen, mulch and GA3 on multi-purpose pumpkin cannot be entirely depicted by analysing preharvest physiology. Adoption and application of treatments that promote desired preharvest physiology of multi-purpose pumpkin is recommended, including 50 kg N/ha to enhance stomatal conductance and leaf chlorophyll, and unpainted rice straws to enhance leaf chlorophyll content and photosynthesis.
Influence of Rhizobium Inoculation and Phosphate Rock Fertilizer Application on Growth and Yield Components of Green gram (Vigna radiata) in Tharaka-Nithi County, Kenya
(Asian Journal of Research in Crop Science, 2021-03) Mbaka, F. K.; Oloo-abucheli, G. O.; Njoroge, P. K.; Ndukhu, H. O.; ; ;
Green gram is an important drought tolerant grain legume crop in Kenya. In Tharaka Nithi County green gram is as a major source of food security. Hence, there is need for a cheap and sustainable system of agricultural production is needed to increase its production. The legume/Rhizobium symbiosis in combination with phosphate rock offers a natural system for improving green gram nitrogen fixation. Therefore, this study was aimed at determining the effect of Rhizobium and phosphate rock fertilizer application on growth and yield attributes of N26 and KS20 varieties. The study was carried out at Chuka University Horticultural Research Farm for two seasons, November 2019 to January 2020 and February to April 2020. Factorial experiment of 2x2x2 was laid out in a Randomized Complete Block Design (RCBD). There were three factors, variety (N26 and KS20), phosphate rock (0 and 30 kg P ha-1) and Rhizobium MEA 716 (0 and 100 g ha-1). The experiment contained eight treatments which were replicated three times. The data was collected fortnightly on four randomly selected plants on parameters such as plant height, number of leaves, branches, pods, total dry biomass, shoot and root dry weight and grain yield. These data was analysed using Statistical Analysis Software (SAS). Significant means are separated using Least Significant Difference (LSD) at probability level of 5%. Results for both seasons indicated that combined application of Rhizobium MEA 716 Rhizobium 100 g ha-1 and phosphate rock 30 Kg ha-1 phosphate under variety in treatment (R1P1V2) showed significantly (P<0.05) higher plant height (76.07 cm), number of branches (14.08 plant-1), shoot dry biomass (52.01 g plant-1), root dry biomass (7.60 g plant-1), total dry biomass (146.4 g plant-1), number of pods (84 plant-1) and yield (2158 kg ha-1) compared to variety N26 in treatment (R1P1V1). Therefore, combination of Rhizobium MEA 716 100 g ha-1 and phosphate rock 30 Kg ha-1 under variety KS20 led to improved growth attributes equally yield components of KS20 variety over N26. From these findings, application of Rhizobium MEA716 at 100 g ha-1, and 30 Kg ha -1 phosphate rock under variety KS20 was recommended for improved and a sustainable green gram production in the study area.
Enhancing preharvest physiology of multi-purpose pumpkin using combined nitrogen, mulch and gibberellic acid
(Chuka University, 2022-03) Isutsa, D. K.; Mwaura, M. M.; ; ;
In recent times, it has become apparent that multi-purpose pumpkin (Cucurbita moschata Duch.) is a very important crop since its leaves, fruits and seeds can be eaten as vegetables, snacks and blended dishes to boost household food and nutritional security. However, it is regarded as a low value crop, leading to poor cultivation, comprehension of preharvest physiological behaviour, and maximization of productivity in Kenya. Consequently, a study was conducted to assess the effects of combined nitrogen, mulch and gibberellic acid (GA3) in enhancing its preharvest physiology of pumpkin. Four N rates of 0, 50, 100 and 150 kg N/ha supplied as CAN, three mulch types as none, unpainted, and black-painted rice straw, and three GA3 rates of 0, 40 and 80 mg/L were assessed. The experiment was arranged in split-split plots in randomized complete block design, replicated three times in two seasons, and each plant occupied 2 m x 2 m space. Nitrogen was applied to main plots, mulch to sub-plots, and GA3 to sub-sub plots. Pre-harvest physiological variables measured were stomatal conductance, chlorophyll, photosynthesis, and transpiration. Data values were subjected to analysis of variance using SAS Version 9.3. Separation of significant means was done using the least significant difference test at α = 0.05. Results showed that nitrogen and mulch individually and interactively did not significantly (P > 0.05) affect most preharvest physiological parameters. The effect of GA3 was not significant on stomatal conductance and leaf chlorophyll, but it was negative and significant on both photosynthesis and transpiration in season 1 which was drier than season 2. Based on the present results, the influence of combined nitrogen, mulch and GA3 on multi-purpose pumpkin cannot be entirely depicted by analysing preharvest physiology. Adoption and application of treatments that promote desired preharvest physiology of multi-purpose pumpkin is recommended, including 50 kg N/ha to enhance stomatal conductance and leaf chlorophyll, and unpainted rice straws to enhance leaf chlorophyll content and photosynthesis.
Incidence and Severity of Turcicum Leaf Blight Caused by Exserohilum turcicum (pass.) Leonard and Suggs) on Sorghum Populations in Different Regions of Tharaka Nithi County, Kenya
(Journal of Scientific and Engineering Research, 2019) O. Ogolla, Fredrick; M. Muraya, Moses; O. Onyango, Benson; ; ;
Sorghum (Sorghum bicolor (L.) Moench) is a drought tolerant food crop preferred by subsistence farmers in dry areas which experience low annual rainfall. However, Turcicum Leaf Blight (TLB) caused by Exserohilum turcicum has threatened sorghum production in the world. New sorghum varieties have been introduced into the Kenyan production systems, including the drier parts of Tharaka Nithi County to boost yield and thus meet the increased demands for food and as a raw material by brewing industries. Nonetheless, challenges due to infection by TLB have negatively impacted on sorghum production resulting from damaged photosynthetic leaves. This study was conducted to determine the incidence and severity of TLB on sorghum populations indifferent regions of Tharaka Nithi County. Sorghum farms in eleven villages for the study were selected by multistage random sampling. The study was conducted between the month of January and June 2018. Data analysis was done by SAS software version 9.3 and significantly different means separated using LSD test at 5% probability level. There was statistically significant difference in the severity and incidence of E. Turcicum leaf blight on sorghum population from different regions in Tharaka Nithi County (P<0.05). Disease TLB occurred in all the villages surveyed though at different frequencies. The disease incidence was higher at Kithaga, and Nkairini recording 74.45% and 55.93%. and lowest at Gatuntu and Gituntu both recorded the disease incidences 12.22%. Thus, farmers should be educated on sorghum TLB management for increased sorghum production and higher income to farmers.

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