Department of Plant Science

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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
Agronomic characterization of soybean and bambara groundnut genotypes grown on different soils of Lake Victoria Basin
(Fundamental and Applied Agriculture, 2020-04-29) Benson O Onyango; Fredrick Otieno Ogolla; ; ;
Neglect and under-utilization of legumes such as soybeans and bambara groundnuts are the reason for increased food insufficiency in the Lake Victoria basin. Diversification of legumes into the cropping systems of Lake Victoria basin ensures protein rich diets and improved soil fertility. This study was carried out to evaluate agronomic characters of two soybean varieties and two bambara groundnut landraces cultivated on different soils of Lake Victoria basin. Seeds of two bambara groundnut landraces; Kakamega Cream (KAKC) and Busia Brown (BUSB) were collected from farmers in Kakamega and Busia counties, respectively in Kenya. Soil sampling was done at selected farmers’ fields with no history of inoculation in Kisumu, Port Victoria, Kendu bay and Karungu within Lake Victoria basin. Screen house experiment was performed in plastic pots with two plants of each cultivar. Randomized Complete Block Design was used. Agronomic characters of BUSB and KAKC landraces differed significant (p<0.05). Bambara groundnuts performed better in Port Victoria and Kendu bay soils than Kisumu and Karungu. Agronomic performance of two soybean varieties SB19 and ‘Safari’ on soils from four sites in Lake Victoria basin was significant (p<0.05). Soybeans yield in Port Victoria and Kendu bay soils was better compared to Kisumu and Karungu soils. Agronomic performance of bambara groundnuts and soybeans were influenced by soil type. Port Victoria and Kendu bay soils resulted in better growth compared to Kisumu and Karungu soils. Landrace KAKC and SB19 had better agronomic performers and are recommended to farmers and seed companies for certified seed production.
The analogy of simple and inter simple sequence repeat markers in the assessment of genetic diversity of pumpkin accessions in Kenya
(Innspub, 2020-09) Kiramana, James; Isutsa, Dorcas Khasungu; Nyende, Aggrey Bernard; ; ;
Pumpkin is found growing in many parts of Kenya although its genetic variation has not been determined using available molecular markers. This study compared SSR and ISSR efficacy in assessing diversity of 139 pumpkin accessions using the multiplex ratio (MR), polymorphic information content (PIC), effective multiplex ratio (EMR), marker index (MI), different (Na) and effective (Ne) alleles, Shannon index (I), expected (He) and unbiased expected heterozygosity (UHe), analysis of molecular variance (AMOVA), clusters and mantel correspondence. DNA ranged from 27-2992ng/µl and 0.45-2.1 of 260/280nm. SSR detected 23 total alleles and 4.6 average alleles of 100-700bp. ISSR detected 152 total alleles and 21.7 average alleles of 200-2000bp. Amplified and polymorphic DNA bands were 437 and 117 for SSR, 512 and 391 for ISSR, respectively. Total and polymorphic bands MR was 87.4 and 29.4 for SSR, 73.1 and 55.9 for ISSR, respectively. PIC, EMR and MI for ISSR were higher than for SSR. Markers with high polymorphism portrayed high EMR and MI. SSR PKCT-122 and ISSR 17899A had the highest polymorphism, PIC, EMR and MI. Ne, I, He and UHe was high for SSR, while Na was high for ISSR. AMOVA revealed significant (P=0.01; P=0.02) differentiation. Genetic diversity was 14% and 7% among, 86% and 93% within accessions for SSR and ISSR, respectively. Three clusters independent of geographic origin were revealed. SSR and ISSR Euclidean matrices showed positive significant (r=0.272, P=0.0001) correlation, which implied they reflected the same genetic diversity. Hence, the genetic diversity of pumpkins can be assessed effectively using either SSR or ISSR markers.
Analysis of Institutional Factors Affecting Optimization of Coffee Yields in Chuka Sub-County, Tharaka-Nithi County, Kenya
(Research gate, 2020) Kihoro, David M.; Gathungu, Geofrey K.; ; ;
The importance of coffee production in the world economy cannot be ruled out due to its contribution in the developing countries in areas such as creation of employment and rise in foreign exchange. Most of the coffee producing countries in the world have come up with strategies to increase their quantity and improve the quality of their produce. In Kenya, the government have also come with numerous policies to support coffee production at the farm level but production of coffee in Kenya has since 1989 crop year been declining. There has been emergence of other enterprises that are profitable than coffee production such as real estate and dairy sector in most of the coffee-growing zones, but there are many farmers who have been determined to maintain coffee production. Despite the efforts made by the government to maximise coffee production in terms of quality and quantity, production has shown a downward trend, with some farmers completely doing away with production This study was aimed at assessing the factors that affect optimization of coffee production in Chuka sub-County, Tharaka-Nithi County. Proportional stratified random sampling was used to select a sample of 153 respondents from a population of 7,428 small-scale coffee farmersfrom ten cooperatives in the sub-County. The findings of the study indicated that access to extension, access to research and management of coffee cooperative were essential in coffee production with a mean agreement of 58.33%. The research established that access to extension (5%) and management of cooperatives (5%) were statistically significant while access to research at (5%) was statistically insignificant. Similarly, access to extension services increased optimization by 91%, poor management of coffee cooperatives reduced production by 45.1%, while access to research increased coffee production by 51%. Therefore, it is important to ensure farmers access extension services, research and there is improved management of coffee cooperatives.
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.
APPLICATION OF BOX-BEHNKEN DESIGN AND RESPONSE SURFACE METHODOLOGY FOR OPTIMISATION OF BUTTERNUT (CUCURBITA MOSCHATA) FRUIT YIELD USING FERTILISERS AND PINCHING
(Afr. J. Hort. Sci., 2022) Njiru, Rachael W.; Muraya, Moses M.; Gathungu, Geoffrey K.; ; ;
Butternut (Cucurbita moschata) production is constrained by poor agronomic practices such as suboptimal application of fertilizers and lack of appropriate pinching practices aimed at improving the number of female flowers. Moreover, many farmers mix animal manures and inorganic fertilisers in one hill without any recommended rates. The objective of this study was to apply Box-Behnken Design and Response Surface Methodology to optimize butternut fruit yield using poultry manure, NPK fertiliser and pinching. The experiments were conducted in two trials in 2019 and 2020 at Karingani ward, Chuka. A Factorial experiment laid down in Randomised Complete Block Design was used. The factors included poultry manure at three levels (0, 5 and 10 tons/ha), NPK at three levels (0, 100 and 200 kg/ha of NPK 17:17:17) and pinching at three levels (0, 4th node and 6th node). Butternut variety Atlas F1 was used. Data was collected on the fruit yield. The input variables were modelled and maximised using Box-Behnken design (BBD) and Response Surface Methodology. The optimisation of the input variables revealed that the optimal levels of application of NPK and poultry manure that can lead to maximum yield of butternut fruits were 505 kg/ha of NPK and 8102 kg/ha poultry manure. The model also showed that pinching should be conducted 30 days after planting (equivalent to pinching at 3rd node) for optimal butternut fruit yield. The study demonstrated that BBD can serve as an inexpensive tool in optimization of the butternut fruit production. However, there is need for further field studies to validate the findings of this study in order to accurately advice farmers on optimum combined application of manure, NPK and pinching time.
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.
Are the AgriTech Technologies Available, Adaptable and Practical to Young Farmers? Lessons from Tomato farmers in Kirinyaga County, Kenya
(Journal of Agricultural Science and Food Research, 2020) Kamau, Joram Ngugi; Kiprop, Ibrahim Nyariki; Kipruto, Geoffrey Kosgei; ; ;
Information and communication technologies (ICTs) in particular mobile phone applications and internet are transforming how agribusiness is carried out in some parts of developing countries including Kenya. The spread of information and communication technologies (ICTs), especially mobile phones, in developing countries has been both extensive and rapid creating a need to assess its efficiency and the rate of adoption. This study aimed at examining how farmers in the county integrate technological innovations in the production and marketing stage of tomato in the sampled area. The objective of the study was to examine how small scale farmers are integrating social media marketing platforms, digital credit, agricultural value addition and artificial intelligence in their production and marketing stages in the agricultural value chain. The results indicate statistically significant positive effects of AgriTech Technologies on farm income (t-prob 0.000<0.05). The results notably indicate that using social media marketing platforms has the highest positive contribution to a unit change in farm income (β= 3.84).Smallholder farmer’s ability to access knowledge, networks, and institutions essential for improving productivity, food security, and employment opportunities is a big challenge especially in rural areas where internet connectivity and poverty levels are alarming.
A Backward Regressed Capsule Neural Network for Plant Leaf Disease Detection
(Science Publications, 2022) Jepkoech, Jennifer; Kenduiywo, Benson Kipkemboi; Mugo, David Muchangi; Tool, Edna Chebet; ; ;
This study investigated the introduction of backward regression coupled with DenseNet features in a Capsule Neural Network(CapsNet) for plant leaf disease classification. Plant diseases are considered done of the main factors influencing food production and therefore fast crop disease detection and recognition are important in enhancing food security interventions. CapsNets have successfully been adopted for plant leaf disease classification however, backpropagation of signals to preceding layers is still a challenge due to low gradient flow. In addition, parameter and computational complexities exist due to complex features. Therefore, this study implemented a loop connectivity pattern to improve gradient flow in the convolution layer and backward regression for feature selection. We observed a 99.7% F1 score with backward regression and 87% F1 score without backward regression accuracy on testing our framework based on the standard Plant Village (PV) dataset comprising ten tomato classes with 9080 images. Additionally, CapsNet with backward regression showed relatively higher and stable accuracy when sensitivity analysis was performed by varying testing and training dataset percentages. In comparison Support Vector Machines (SVM), Artificial Neural Networks (ANN),AlexNet, ResNet, VGGNet, Inception V3, and VGG 16 deep learning approaches scored 84.5, 88.6, 99.3, 97.87, 99.14, and 98.2%, respectively. These findings indicate that the introduction of backward regression of features in the Caps Net model may be a decent and, in most cases superior and less expensive alternative for phrase categorization models based on CNNs and RNNs. Therefore, the accuracy of plant disease detection may be enhanced even further with the aid of the fusion of several classifiers and the integration of a backward regressed capsule neural network.
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.
Cactus invasion: A Threat to Biodiversity and Food Security
(Office of DVC Research, Innovation and Enterprise, 2020-01) Dr W. Githae, Eunice; ; ;
Invasive cactus degrades rangelands and reduces availability and accessibility of pasture and other natural resources. Cactus invasion reduces biodiversity hence affecting ecosystem goods and services that are essential for human well-being. There is limited information and lack of public awareness on the harmful impacts caused by invasive cactus. Rural households lose between 50 and 100 thousand shillings a year because of cactus
Climate change adaptation of potato (Solanum tuberosum L.) 2: Influence of Biozyme® rate on potato growth and development.
(2013-07-31) Karanja, B. K.; Isutsa, D. K.; Aguyoh, J. N.; ; ;
Potato is an important food crop worldwide. Growers adopt potato production due its short growing season and poor soils tolerance. They use agrochemicals to improve growth under unreliable rainfall. Biozyme® foliar feed is widely used to hasten maturity and enhance yields of crops. It is said to be a storehouse of hormones and nutrients that improve crop health. It contains major hormones along with primary and secondary nutrients. This study determined if Biozyme® could overcome deficit rainfall and enhance potato growth to adapt to climate change. The arrangement was split plots in randomized complete block design replicated three times and repeated once. Main plots were assigned to potato cultivar (Tigoni and Asante) and subplots to Biozyme® rate (0, 125, 250, 500 and 750 ml/ha). Each subplot was planted with 28 tubers spaced at 30 cm x 70 cm in four rows. A distance of 1 m separated plots. Plant growth in height, stem diameter and aboveground biomass increased with increase in Biozyme® rate. The 750 ml/ha rate increased height by 41%, stem diameter by 55.34%, chlorophyll by 19.45 spads, flowers by 21.86%, as compared to the control rate (0 ml/ha), but was not significantly different from 500 ml/ha rate. Increased height, leaf area index, chlorophyll content, aboveground biomass is good as it enhances photosynthate synthesis and translocation to edible tubers. Thus, foliar-feeding potato plants with at most 500 ml/ha Biozyme® is recommended for hastening growth in regions with deficit rainfall.
Climate change adaptation of potato (Solanum tuberosum L.): Influence of Biozyme® rate on potato yield, quality and mineral nutrient uptake
(2013-07) Karanja, Benard K.; Isutsa, Dorcas Khasungu; Aguyoh, Joseph Nyamori; ; ;
Potato (Solanum tuberosum L.) is an important food crop worldwide. Growers prefer potato because of its short growing season and tolerance to poor soils. Growers are using different agrochemicals so as to improve tuber yield, quality and maturity period under erratic and unreliable rain patterns. BiozymeÂ® foliar feed is widely used to hasten maturity and enhance yields of crops. BiozymeÂ® is said to be a storehouse of hormones and nutrients that improve the health of a crop. It contains major hormones along with primary and secondary mineral nutrients. This study determined BiozymeÂ® rate that is lower than the commercially recommended 500 ml/ha to curb overuse and misuse, but still enhance potato tuber yields under climate change deficit rainfall adaptation. The study was set up in split plots arranged in a randomized complete block design, replicated three times and repeated once. Main plots were assigned to two contrasting potato cultivars (Tigoni and Asante), while subplots were assigned to BiozymeÂ® rate (0, 125, 250, 500 and 750 ml/ha). Each subplot was planted with 28 seed potato tubers spaced at 30 cm Ã— 70 cm in four rows. A distance of 1 m separated plots. The 750 ml/ha BiozymeÂ® significantly (P<0.05) increased total potato tuber yields by 3Ã— to 7Ã—, reduced unmarketable tubers by up to 3Ã—, enhanced dry matter by 10% and starch by >2Ã— compared to the 0 ml/ha BiozymeÂ®. The 0 ml/ha BiozymeÂ® produced 2-11 t/ha and 7-14 t/ha in "Tigoni' and "Asante', while the 750 ml/ha BiozymeÂ® produced 25-33 t/ha and 39-43 t/ha in "Tigoni' and "Asante', respectively. The 750 ml/ha BiozymeÂ® also increased leaf tissue N by >1%, P by >100 ppm and K by > 9 ppm in both seasons and cultivars. The difference in performance for 500 and 750 ml/ha BiozymeÂ® was always not significant (P>0.05). Thus, it is not advisable to foliar-feed potato plants using BiozymeÂ® rates eÃ—ceeding 500 ml/ha since this will amount to overuse and misuse and eÃ—acerbate tuber perishability. Slightly lower BiozymeÂ® rates than 500 ml/ha may be recommended to guarantee production of "hardier" potatoes ideal for safe handling
Coffea arabica cultivar Ruiru 11 sibs exhibit significant variation in plant regeneration through direct somatic embryogenesis.
(ISDS LLC, Japan, 2018) Mayoli, Rose Nduku 1*; Isutsa, Dorcas Khasungu 2; Nyende, Aggrey Bernard 3; ; ;
This experiment evaluated the response of 11 selected recalcitrant coffee ‘Ruiru 11’ sibs to plantlet regeneration through direct somatic embryogenesis. Third leaf pair explants from field-grown mother plants were harvested, sterilized and induced for up to 12 months in half-strength Murashige and Skoog basal salts medium supplemented with 1 ml/L thidiazuron, 0.2 g/L thiamine, 0.1 g/L nicotinic acid, 0.1 g/L pyridoxine, 20 g/L sucrose, 100 mg/L myoinositol, 100 mg/L cysteine and 3 g/L gelrite. Embryos were sequentially transferred to media for shooting for 8 weeks, rooting for 6 weeks and weaning for 4 weeks. The explants were effectively sterilized using 30% sodium hypochlorite (3.85 v/v) for 20 minutes. The sibs showed significant (P<0.05) genotypic variation, with sibs 11, 41, 71 and 121 from ‘Catimor 86’and those from ‘Catimor 90, 128 and 134’ regenerating somatic embryos, whereas sibs 52 and 142 from ‘Catimor 88’ failing to do so. Sib 137 had the highest 63% embryogenic rate and 3.7 average embryos per explant. Sibs 71 and 137 embryos developed longest shoots, with 84% of sib 137 embryos developing shoots. Sibs 93 and 71 embryos developed longest roots, with 91% of sib 71 embryos developing roots. About 91% of sib 71 plantlets survived acclimatization. Sibs 137, 71 and 93 were classified as highly embryogenic, whereas sibs 52 and 142 were non-embryogenic. Sib 71 best responded to plantlet regeneration through direct somatic embryogenesis. Therefore, sib 71 plantlets should be used in future as stocks for mother plants for mass propagation of ‘Ruiru 11’.
COLONIAL ROOTS OF FOOD SHORTAGE IN KENYA: THE MARGINALIZAION OF THE AGIKUYU WOMEN’S INDIGENOUS KNOWLEDGE SYSTEM ON FOOD CROP PRODUCTION
(International Journal of Liberal Arts and Social Science, 2020-08) Muraya, Dr. Martha Wanjiru; Ngare, Dr. Lazarus Kinyua; Gathungu, Dr. Geofrey King’ori; ; ;
Since pre-colonial period, the Indigenous Knowledge Systems (IKS) on food crop production have played a significant role in enhancing the supply of food in the society. This paper examines the effects of marginalization of Agikuyu Women‟s Indigenous Knowledge Systems (AWIKS) on food supply during the colonial period in Kiambu County of Kenya. This is done to show how the colonial land alienation, commercialized agriculture, and forced labor policies undermined and neglected the AWIKS on food crop production, which contributed to lack of enough food supply in the households. The findings demonstrate that due to intensive land alienation, the Agikuyu women lacked enough productive land for cultivation which led to poor crop harvest, inadequate space for food storage facilities, and increased destruction and spoilage of food crops due to poor storage. The European commercial fast growing high yield food crops were more vulnerable to increased temperatures, low rainfall, and they required high farm inputs and mechanization which were not affordable by the Agikuyu women. The paper concludes that the integration of indigenous knowledge systems and western modern scientific agricultural knowledge systems on food crop production can be an effective way of ensuring food security.
Combining Host Plant Resistance, Selective Insecticides, and Biological Control Agents for Integrated Management of Tuta absoluta
(2020-07-07) Nderitu, Peris Wangari; Jonsson, Mattias; Arunga, Esther; Otieno, Mark; Muturi, John Jamleck; Wafula, Geoffrey O.; ; ;
Combination of pest management strategies that minimize pesticide use and conserve natural enemies is important for a sustainable environment. Overreliance on synthetic insecticides in the management of Tuta absoluta has led to pesticide resistance leading to difficulties in managing the pest. In this regard, alternative measures need to be put in place to reduce the effects of this pest. The objective of this study was, therefore, to assess the effectiveness of host plant resistance, biological control, and selective insecticides when used in combination, in the management of T. absoluta in tomato production. The study was set up in a greenhouse in a completely randomized design involving two tomato varieties, an insecticide (chlorantraniliprole), and a biological control agent(Macrolophus pygmaeus), applied singly or in combination. Data were collected on T. absoluta damage from the lower, intermediate, and upper leaves. The results from this study show that a combination of insecticide with a moderately resistant variety had a significantly lower T. absoluta damage as compared with a susceptible variety combined with an insecticide. However, the moderately resistant variety when combined with insecticide showed no effect when the biological control agent was added. The susceptible variety significantly reduced T. absoluta damage when combined with the biological control agent. These results indicate that treatment combinations in insect pest management can be utilized. The present study results indicate that using a moderately resistant variety (Riogrande VF) in combination with the insecticide chlorantraniliprole (Coragen®) and a susceptible variety (Pesa F1) in combination with the biological control agent (M. pygmaeus) can improve T. absoluta management. Under good habitat management, the susceptible variety will perform equally as the moderately resistant variety due to suppression of the T. absoluta populations by natural enemies. These findings show the importance of environmental conservation both by enhancing natural enemy abundance and use of selective insecticide in the management of T. absoluta in tomato production. Combinations in this present study are likely to reduce insecticide doses, thereby reducing the cost of production and enhancing environmental compatibility with natural enemies.
Contribution of multi-purpose pumpkin (Cucurbita moschata Duch.) to the economy of selected Kenyan small-scale households
(Science Publishing Group, 2019-03-19) Kiharason, Jedidah Wanjiku; Isutsa, Dorcas Khasungu; ; ;
Pumpkin (C. moschata Duch.) fruit is a highly nutritious horticultural crop with great potential for commercialization. However, in Kenya many households do not buy and utilize pumpkins regularly, leading to low demand. These scenarios increase post-harvest losses and provide no incentive for farmers to increase production in Kenya, which has an abundance of pumpkin landraces that unfortunately remain under-exploited and under-utilized. Their distribution and marketing is a great challenge due to easy perishability. Horticultural crops experience losses in quality and quantity in between harvest and consumption. The magnitude of post-harvest losses in fresh fruits and vegetables is estimated to range from 20% to 50% in developing countries. The present study determined marketability of fresh fruit, and the spoilage rate of fresh fruit in the various presentation formats (eighth, quarter and half slices and a control of whole fruit either wrapped or not with cling film). Selling was facilitated by four market women in Nyeri County of Kenya. Statistical analysis showed significant differences (P<0.05) in number of spoilt pieces over time, and between number of days to spoilage of whole fruit, compared to slice fruit. More quarter and half slices got spoiled after a few days of presentation to buyers. Nonetheless, quarter slices had the highest (54.5%) pieces sold, while half slices had the fewest (9.8%) pieces sold. However, no significant differences occurred in average number of pieces sold, or in amount of money from sale of fruit pieces of different presentation formats. Most consumers preferred buying smaller slices. Therefore, adoption and promotion of pumpkin presentation formats that effectively increase shelf-life is recommended to enhance production and utilization in Kenya.
Cultural, Morphological and Biochemical Identification of Xanthomonas Spp the Causative Agent of Bacteria Leaf Spot in Tomatoes in Wanguru, Mwea, Kirinyaga County, Kenya
(rsisinternational, 2019-04) Fredrick O. Ogolla; DaisyB. Neema; ; ;
Bacteria diseases are major constraints in commercial agriculture. Bacteria diseases have continuously caused huge loss to both conventional and organic farming systems globally. Bacteria leaf spot is a tomato disease of concern whose management remains a challenge across the globe. The pathogen Xanthomonas campestris pv vesicatoria the causative agent of leaf spot in tomato has been isolated and positively identified in many countries to enable control. In Kenya, tomato farmers have experienced losses associated with bacterial diseases despite using available control strategies. Application of control mechanisms by majority of farmers heavily rely on symptoms on plants other than laboratory facts on pathogen identification. As such wrong chemicals have been applied which have led to development of resistance due to pathogen evolution. Scientific identification of pathogen is necessary to enable application of accurate and effective management strategy. Nonetheless, this has scarcely been done for tomato bacteria diseases in Kenya. The objective of this study was to isolate and identify bacteria leaf spot pathogen of tomato from Wanguru area in Mwea, Kirinyaga county in Kenya using nutrient agar, differential staining and selected biochemical methods. A total of ten tomato heavily infected leaves were selected randomly from different farms. The colonies were generally yellow on the surface of nutrient agar. Results of differential staining showed gram negative rods while biochemical tests slightly varied. Based on totality of cultural, morphological and biochemical tests results, we concluded that Xanthomonas campestris pv vesicatoria is responsible for leaf spot tomato disease in Wanguru. However, we recommend the inclusion of molecular tool for proper identification.
Current characteristics of cassava mosaic disease in post-epidemic’ areas increase the range of possible management options.
(Association of Applied Biologists, 2006-06-05) Mallowa, S. O.1; Isutsa, D. K.1; Kamau, A. W.1; Obonyo, R.2; Legg, J.P 2,3; ; ;
As a case study to document the current characteristics of cassava mosaic virus disease (CMD) in postepidemic areas, surveys were carried out, in 2003 and 2004, in Siaya District of western Kenya. This was an area affected by a severe CMD pandemic in the late 1990s. Data recorded on cassava varieties were CMD incidence, severity index and number of adult whiteflies. Farmers (174) were interviewed on their understanding of the disease and their knowledge and practice of management interventions. Cassava cultivation was being reestablished, but local landraces predominated. Resistant varieties were present 13% in 2003, and 4% in 2004, of the surveyed fields. Adhiambolera was the most common variety, occurring in 35% and 40% of fields in 2003 and 2004, respectively, and had an average CMD incidence of 82% in 2003 and 73% in 2004. By contrast, the CMD-resistant variety Migyera had a low mean incidence (28% in 2003). The overall incidence for both years was 71%, consisting of 61% as a result of infection through planting diseased cuttings and 10% as a result of whitefly infection. In 2003, the total incidence was 72% and the average severity 2.7 (severity index), while in 2004 the incidence was 78% and the severity 2.6. There were significant severity variations in each division of the Siaya District during the 2 years except for Karemo and Ukwala. The abundance of whiteflies on the top five leaves of plants was low in 2003 but high in 2004, with means of 1 and 16, respectively, over the same seven divisions in both years, although this variation was thought to be because of seasonal factors. East African cassava mosaic virus-Uganda was the predominant geminivirus present in every division. Phytosanitation by farmers was minimal, as evidenced by 29% of farmers using a selection of CMD-free stems for planting and 15% using hand-roguing for CMD management. Occurrence of more than 25% CMD-free plants in 2004, moderate CMD severity and limited spread provide a conducive environment for the use of phytosanitation as a CMD control measure that can be immediately used by farmers growing their own cassava varieties.
Determinants of gender differences in household food security perceptions in the Western and Eastern regions of Kenya
(Cogent food and agriculture, 2019-11-22) Lutomia, Cosmas Kweyu; Obare, Gideon A.; Kariuki, Isaac Maina; Muricho, Geoffrey Simiyu; ; ;
In addition to Intra-household resource allocations and internaldynamics of decision-making, gendered perceptions on household food securityplay a critical role in households’nutritional status, especially in developing coun-tries. However, evidence on the role of gender-based perceptions on households’food security and related implications on the households’nutritional status islimited. This study examines the determinants of gender-disaggregated householdfood security perceptions among smallholder farming households. We used twopanels of data from households in eastern and western Kenya and employ theHouse hold Food Insecurity Access Scale to measure perceptions of household foodinsecurity, and the random effects generalized ordered probit model to evaluate thedeterminants of security perceptions across gender. The results reveal that thefactors that influence food security perceptions vary across gender. The educationlevel of household head and the number of relatives were negatively associatedwith female perceptions of household food insecurity, whereas the householddependency ratio was positively associated with female perceptions of householdfood insecurity. In contrast, age and gender of household head were positively

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