School of Agriculture and Biotechnology

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Addressing the education and training needs of the tea sector in Kenya: The case of the School of Agriculture and Biotechnology at Karatina University
(2015) Kamotho, G.N.; Mathenge, P.W.; Kamiri, H.W
In Kenya, personnel working in the tea sector are drawn from various fields of specialization such as general agriculture, horticulture, engineering and economics. There are no special training programmes to train personnel at degree, diploma and certificate levels on tea in the country. The training needs assessment carried out by Tetralink Taylor and Associates East Africa in 2010, observed that there are training needs for each segment along the tea value chain. It is against this background that the School of Agriculture and Biotechnology, Karatina University recognized the training gap in tea value chain and decided to design and mount specialized programmes in tea. The paper was informed by the Training Needs Report of 2010 by the Tetralink Taylor and Associates East Africa and other secondary data from published articles on tea. From the documentary analysis, it was established that training of personnel for tea sector was long overdue. Karatina University has taken the right direction towards this crucial aspect of human resource capacity building. It is recommended that Karatina University be a centre of excellence for tea information resource and develop more tea academic programmes for manpower training at bachelors, master and doctorate degree levels.
Allelic Variation of Terpene Synthases Drives Terpene Diversity in the Wild Species of the Freesia Genus.
(2023-03-18) Bao, Tingting; Kimani, Shadrack; Li, Yueqing; Li, Hongjie; Yang, Song; Zhang, Jia; Wang, Qiuyue; Wang, Zhaoxuan; Ning, Guogui; Wang, Li; Gao, Xiang
Terpene synthases (TPSs) play pivotal roles in conferring the structural diversity of terpenoids, which are mainly emitted from flowers, whereas the genetic basis of the release of floral volatile terpenes remains largely elusive. Though quite similar in sequence, TPS allelic variants still function divergently, and how they drive floral terpene diversity in closely related species remains unknown. Here, TPSs responsible for the floral scent of wild Freesia species were characterized, and the functions of their natural allelic variants, as well as the causal amino acid residues, were investigated in depth. Besides the eight TPSs previously reported in modern cultivars, seven additional TPSs were functionally evaluated to contribute to the major volatiles emitted from wild Freesia species. Functional characterization of allelic natural variants demonstrated that allelic TPS2 and TPS10 variants changed enzymatic capacity while allelic TPS6 variants drove the diversity of floral terpene products. Further residue substitution analysis revealed the minor residues determining the enzyme catalytic activity and product specificity. The clarification of TPSs in wild Freesia species reveals that allelic TPS variants evolved differently to determine the interspecific floral volatile terpenes in the genus and might be used for modern cultivar improvement.
The anti-inflammatory properties of Kenyan tea
(2015) Karori, S.M .; Ngure, R.M.; Wanyoko, J.K.; Wachira, F.N.
An in vivo study was carried out to determine the effect of different types of Kenyan tea extracts on male Swiss albino mice infected with Trypanosoma brucei brucei isolate KETRI 2710. The isolate produced a similar clinical picture after a pre-patent period of five days post-infection (DPI). Parasitemia levels in the untreated mice and those given different tea developed exponentially at similar rates reaching the peak of parasitemia 8 DPI. Between 9 and 13 DPI parasitemia decreased more rapidly in tea treated compared to the untreated mice which indicated that tea lowered parasitemia. Anaemia indicated by a fall in erythrocyte packed cell volume (PCV) occurred within 4 DPI and remained below the normal levels until the terminal stages of the disease. A significant difference (P < 0.05) was observed 11 DPI between the tea treated and the untreated mice indicating that tea enhanced resistance to erythrocyte destruction. Mice treated with tea exhibited significantly (P < 0.01) reduced parasite induced hypoalbuminemia as compared to the untreated demonstrating that tea ameliorated inflammation induced by T. brucei brucei. Black tea, which is the principle tea product from Kenya, displayed remarkable properties some even comparable to those of green tea. Tea was more efficacious than dexamethasone, an established anti-inflammatory drug, demonstrating its therapeutic potential.
Antimicrobial acitivity of extracts from Tephrosia vogelii Hook F.
(2007-01-29) Wanga, B. N.; Akenga, T.; Imbuga, M.; Gitonga, L .; Olubayo, F.; Namungu, P.
The dichloromethane extracts of the root and leaf of Tephrosia vogelii Hook F. (Family: Papilionaceae) grown in Kenya, were subjected to antimicrobial assays against Staphylococcus aureus, Escherichia coli and Fusarium phoseolida. The minimum inhibition concentrations (MIC) ranged between 0.25 to 6.4 μg/ml for all the microorganisms tested. The crude root and leaf extracts were also toxic to the brine shrimps, organisms used as indicators of toxicity (LC50: 0.960; 0.958 μg/ml, respectively). Chromatographic separation led to the identification of (6aß, 12aß, 5'ß)-6a, 12a, 4',5'-tetra hydro-2,3-dimethoxy 5'-ß- isopropenyl–furano (3',2': 8,9)-6H-rotoxen-12-one, (rotenone) in 9.75% yield, (roots), and 11.75% (leaves). Characterisation was achieved by use of spectroscopic techniques and comparison with rotenone standard and literature data. Novel HPLC conditions for purification of rotenoids were established. The MIC of rotenone against the tested microbes was found to be 5.2 and 1.0 μg/ml for Staphylococcus aureus and Escherichia coli respectively, while the LC50 against the brine shrimps was found to be 3.20 μg/ml. The findings indicate that the extracts of T. vogelii contain metabolites that have antimicrobial activity comparable to other medicinal plants.
Antioxidant, antimicrobial and synergistic activities of tea polyphenols
(2015) Koech, K.R.; Wachira, F.N.; Ngure, R.M.; Wanyoko, J.K.; Bii, C.C.; Karori, S.M.; Kerio, L.C.
Microbial resistance to conventional antibiotics has become an increasing global problem and there is a need to find out novel, potent antimicrobial agents with alternative modes of action as accessories to antibiotic therapy. This study investigated the antioxidant, antimicrobial and synergistic properties of tea polyphenols. The tea germplasm from Kenya, China and Japan that are grown in Kenya were characterised for their biochemical profiles. The total phenolic content, theaflavins and thearubigins content of different tea products used in this study were determined spectrophotometrically according to Folin-Ciocalteus and flavognost methods respectively. The individual catechin contents were characterised by high performance liquid chromatography (HPLC) and identified according to their HPLC retention times, elution order and comparison with authentic standards. The antioxidant activity of tea polyphenols was determined using UV-Vis spectrophotometer on its ability to scavenge 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical. The Agar Disc Diffusion method was used to screen for antimicrobial and synergistic activities of the tea liquors. Black, green, purple coloured leaf and white (silvery tips) tea products characterised for their biochemical profiles differed significantly in the levels of total polyphenols, total catechins, catechins fractions, theaflavins and thearubigins (P ≤ 0.05). Green, purple coloured leaf (aerated) and black tea from terminal buds and white tea products analysed in this study exhibited slightly higher antioxidant activity compared to black tea. The different types of tea products assayed in this study exhibited significant influence on the inhibition zone diameters against bacteria and fungi exposed to the tea extracts. Methicillin and penicillinase resistant S. aureus ATCC 25923, C. albicans ATCC 90028 and a clinical isolate of C. neoformans were more susceptible to all tea extracts than E. coli and S. typhi. There was synergism between most tea extracts and penicillin G against methicillin and penicillinase resistant S. aureus ATTC 25923.
Article Navigation JOURNAL ARTICLE Evidence for Potential of Managing Some African Fruit Fly Species (Diptera: Tephritidae) Using the Mango Fruit Fly Host-Marking Pheromone
(Entomological Society of America, 2012-12-01) Kachigamba, Donald L.; Ekesi, Sunday; Ndung'u, Mary W.; Gitonga, Linus M.; Teal, Peter E. A.; Torto, Baldwyn
We investigated conspecific and heterospecific oviposition host discrimination among four economically important fruit fly pests of mango in Africa (Ceratitis capitata, Wiedemann; C. fasciventris, Bezzi; C. rosa, Karsch, and C. cosyra, Walker) with regard to host-marking behavior and fecal matter aqueous solutions. The objective of the study was to get insight into the potential of managing these pests using the host-marking technique. Observations were done on mango slices marked by the flies and treated with aqueous solutions of fecal matter of the flies, respectively. In both host-marking and fecal matter experiments, C. cosyra, which is the most destructive species of the four on mango, was exceptional. It only discriminated against hosts treated with its fecal matter but with lower sensitivity while C. capitata and C. fasciventris discriminated against hosts marked by it or treated with its fecal matter and with higher sensitivity. Our results provide evidence for potential of managing some of the major fruit fly species infesting mango in Africa using the host-marking pheromone of the mango fruit fly, C. cosyra.
Assessing the contribution of dolichos bean (Lablab purpureus L. (sweet)) to food security in a changing climate in Kenya
(2022) Kamotho, Grace N.; Kinyua, Miriam G.; Muasya, Reuben M.
Lablab pupureus (L.), is a multipurpose drought tolerant legume which is considered as a minor crop in Kenya, hence, it is underutilized. In Kenya there are few known Lablab genotypes for specific environments. Choice of genotypes to grow is based on colour preference and seed availability, thus low yields are obtained. To assess the status of Lablab production in Kenya, a baseline survey was conducted in Lablab growing localities. A disproportionate stratified sampling was used and a questionnaire was administered to 108 respondents from diverse Lablab growing regions of Kenya. Performance of Lablab genotypes under different environmental conditions was also evaluated. Field trials of forty five (45) accessions of Lablab collected from Rift Valley, Eastern, Coast and Central regions of Kenya were established in three locations with different agro-ecological environments; (Nakuru, Uasin Gishu and Bungoma). The 45 accessions and three environments were factorially combined and replicated three times in a randomized complete block design (RCBD). Results from the survey indicate that most farmers (84.3%) grew Lablab in small acreage of less than 1.0 acre, and only 44.4% of the respondents used the improved Lablab cultivars which were obtained from the Ministry of Agriculture or research stations. Majority (88%) preferred Lablab to common beans and all respondents noted that Lablab fetched more income per unit quantity than common bean. All respondents utilized Lablab dry beans as food. The crop was also utilized as a livestock feed especially during the dry season when no other crops are in the farms by 51.9% of the respondents while 25% used it in conservation agriculture and for soil erosion control. About 20.4% of farmers used the leaves and green pods as vegetables. The study identified accessions that are suitable for different agro ecological zones. In conclusion, Lablab is a crop that is climate resilient and contributes to food security in communities that grow it. It is recommended that dolichos should be promoted in Kenya as a climate change adaptation measure and for enhancing food security.
Assessing the effect of grading on the in vitro availability of Fe, Zn, Cu, Pb and Cd from CTC black tea
(2015) Moseti, K.O.; Kinyanjui, T.; Wanyoko, J.K.; Wachira, F.N.
In vitro analyses of trace element content in biological systems play an increasingly important role in assessing the environmental impact on health. A quantitative study of five trace elements namely Fe, Zn, Cu, Pb and Cd in cut, tear and curl (CTC) black Tea of different grades randomly sampled from four tea growing countries in East Africa, viz., Kenya, Uganda, Rwanda and Tanzania was carried out. The total element content as well as the water extractable content of the tea samples was done by Atomic Absorption Spectroscopy (AAS). Data obtained was analyzed using Graph-pad Prism statistical software for Windows, version 5.0 and P < 0.05 considered to be statistically significant. The significance of the difference between means for black tea and tea infusions was determined by one way ANOVA and the least significant difference test was used for mean separation where significant differences were recorded among group means. It was observed that tea contains the studied elements and only a very small portion of the total element content lixiviates into tea liquor during tea making process. The general extractability pattern of the elements studied was in the order Fe > Zn > Cu > Pb > Cd, indicating that tea is an important dietary source of Fe, Zn and Cu. Taking into account the high tea to water ratio used in preparing the analysed tea extracts, these data is best regarded as the extractability potential of the tea liquor and does not reflect the actual concentrations contained in the tea liquor that we actually consumed. However, the need to enact safety guidelines with regard to the liquor element composition is imperative.
Assessing the efficacy of wild basil (Ocimum americanum L. (Walp)) in the management of cowpea weevil (Callosobruchus maculatus)
(2022-02-28) Mwandikwa, Jacob M.; Kamotho, G. N.
Cowpea (Vigna unguiculata (L.) Walp) belongs to the family Fabaceae and is one of the pulses that suffer postharvest losses greatly. The major insect that attacks stored cowpea seed in Kenya is the cowpea weevil (Callosobruchus maculatus). The insect can damage 100% of stored cowpea seeds causing weight loss of up to 60%. Although insecticides are widely available, they have high potential risks to users and also pollute the environment. In drier areas of Kenya where the pest is common, small-scale farmers use botanicals with varying levels of success. This study sought to assess the effectiveness of a locally available botanical, Ocimum americanum, in the management of the cowpea weevil. Different plant parts of O. americanum, the leaves, flowers and whole mature young plants were dried and ground into powder. From each plant part, 0.5, 1.0, 2.0, 4.0 and 8.0 g were used to determine their effectiveness against the weevil in stored cowpea seed. Two controls were used, that is, no protectant and Actellic super dust. For each treatment, 10 g of cowpea seeds were placed in plastic vials containing ten pairs (male and female) cowpea weevil adults. The experiments were laid out in a completely randomized design at the Kenya Agricultural and Livestock Research Organization (KALRO), Nairobi, Entomology Laboratory. Lowest post-harvest weight loss (3.0 g) of cowpea seed and highest mortality (92.5%) of cowpea weevil was recorded when 8 g of leaf powder were used. Since wild basil is a common weed in drier parts of Kenya such as Mbeere, Tharaka-Nithi, Kitui, Makueni and Mwingi, it can be utilized in these areas as a cheap control bioinsecticide for cowpea weevil.
Assessment of genetic diversity of Kenyan dolichos bean (Lablab purpureus L. sweet) using simple sequence repeat (SSR) markers.
(2016-01) Kamotho, Grace N.; Kinyua, iriam G.; Muasya, Reuben M.; Gichuki, Simon T.; Wanjala, Bramwel W.; Kimani, Esther N.; Kamau, Eliezah N.
The level of genetic relatedness or dissimilarity of Lablab genotypes used by growers in different regions in Kenya has not been determined. In this study, ninety six (96) Lablab accessions collected from various parts of Kenya were characterized based on simple sequence repeat (SSR) molecular markers. Ten SSR primers were used and detected a mean of 4.3 alleles per primer. Expected heterozygosity was on average 0.38. The average polymorphic information content (PIC) was 0.63. Analysis of molecular variance (AMOVA) revealed 15% genetic variation among populations and 85% variation within populations. Highest Nei’s genetic distance of 0.998 was found between Western and Mwingi populations while lowest genetic distance of 0.092 was found between Embu and Meru populations. Lablab purpureus populations exhibited a high level of relatedness as revealed by cluster analysis and dendrogram based unweighted pair group method with arithmetic averages (UPGMA)
Assessment of phenotypic diversity of Kenyan dolichos bean (Lablab purpureus L. sweet) germplasm based on morphological markers
(2017) Kamotho, Grace N.; Muasya, Reuben M.; Kinyua, Miriam G.
In Kenya, lack of phenotypic diversity assessment of Lablab has hindered its improvement. It is common to find that morphologically similar cultivars do not bear the same name while cultivars bearing the same name may not be identical morphologically. The aim of this study was to clear the ambiguity that exists in differentiating between the various phenotypes of Lablab. The morphological method is the oldest and considered the first step in description and classification of germplasms. Forty five accessions of Lablab collected from farmers’ fields in Rift Valley, Eastern, Coast and Central regions of Kenya were planted at Kenya Agricultural and Livestock Research Organization, Njoro farm. A descriptor from Asian Vegetable Research Development Center was used as a guide. Results on means separation showed a high level of variability in quantitative traits and a low level of variability in qualitative traits. Eigen vectors derived from principal component analysis indicated that seed yield per plant, number of pods per plant, plant height and days to 90% mature pods contributed highly to total diversity in Lablab. In conclusion, Lablab germplasm grown in Kenya is morphologically diverse in quantitative traits where different genotypes are distinctly dissimilar.
ASSESSMENT OF PRODUCTION CONSTRAINTS AND CONTRIBUTION OF AVOCADO TO FOOD SECURITY AND INCOME IN THE MOUNT KENYA REGION, KENYA
(2023) Kamotho, Grace N.; Asiko, Lydiah A.; Kibanyu, James K.; Kinyua, Phares R.; Karaya, Rebecca N.; Muthee, Patrick M.; Mwathi, Zipporah M.
ABSTRACT Avocado (Persea americana Mill.) belongs to the family Lauraceae and it is an important crop to rural communities and economies in Kenya. Currently, avocado is grown in several agro ecological zones mainly by small-scale growers (85%) who grow it for subsistence, local markets and export. About 70% of avocado is grown in Central and Eastern region of Kenya. Central region produces 40%, Eastern 28%, Western 13%, Rift Valley 10%, Nyanza 6%, Coast 2% and Nairobi County 1%. The main production areas are Muranga, Kiambu, Thika, Embu, Meru, Taita Hills and Kitale. The aim of this study was to assess the production constraints and contribution of avocado to food security and income in Mount Kenya region. The study population comprised of smallholder avocado farmers. Purposive sampling was done in selecting highest producing sub-counties of avocado in Nyeri, Muranga and Embu counties. Simple random sampling was used to select 40 smallholder farmers from each of the selected sub counties who participated in the survey. Data was collected using a structured questionnaire and analysed using SPSS computer package. Results indicated several constraints in the production of avocado including pests and diseases, lack of quality planting material, poor soils, lack of technical knowledge by avocado farmers and lack of well-structured marketing system. The study identified a gap in value addition of avocado in Kenya. It was also demonstrated that avocado contributes highly to household income and food security. The crop should therefore be accorded priority by policy makers and more research needs to be encouraged especially in the management of pests and diseases. Capacity building to avocado growers should be routinely carried out so as to avoid the many challenges that emanate from lack of technical knowledge. Intervention in value addition of avocado is an aspect that Kenyan county governments need to engage in by investing in cottage industries on avocado processing.
Assessment of Production Constraints and Contribution of Avocado to Food Security and Income in the Mount Kenya Region, Kenya
(2023) Kamotho, Grace N.; Asiko, Lydiah A.; Kibanyu, James K.; Kinyua, Phares R.; Karaya, Rebecca N.; Muthee, Patrick M.; Mwathi, Zipporah M.
Avocado (Persea americana Mill.) belongs to the family Lauraceae and it is an important crop to rural communities and economies in Kenya. Currently, avocado is grown in several agro ecological zones mainly by small-scale growers (85%) who grow it for subsistence, local markets and export. About 70% of avocado is grown in Central and Eastern region of Kenya. Central region produces 40%, Eastern 28%, Western 13%, Rift Valley 10%, Nyanza 6%, Coast 2% and Nairobi County 1%. The main production areas are Muranga, Kiambu, Thika, Embu, Meru, Taita Hills and Kitale. The aim of this study was to assess the production constraints and contribution of avocado to food security and income in Mount Kenya region. The study population comprised of smallholder avocado farmers. Purposive sampling was done in selecting highest producing sub-counties of avocado in Nyeri, Muranga and Embu counties. Simple random sampling was used to select 40 smallholder farmers from each of the selected sub counties who participated in the survey. Data was collected using a structured questionnaire and analysed using SPSS computer package. Results indicated several constraints in the production of avocado including pests and diseases, lack of quality planting material, poor soils, lack of technical knowledge by avocado farmers and lack of well-structured marketing system. The study identified a gap in value addition of avocado in Kenya. It was also demonstrated that avocado contributes highly to household income and food security. The crop should therefore be accorded priority by policy makers and more research needs to be encouraged especially in the management of pests and diseases. Capacity building to avocado growers should be routinely carried out so as to avoid the many challenges that emanate from lack of technical knowledge. Intervention in value addition of avocado is an aspect that Kenyan county governments need to engage in by investing in cottage industries on avocado processing.
An Assessment Of The Physiological Quality Of Sorghum (Sorghum Bicolor L Moench) Seeds Planted By Farmers In Bomet District Of Kenya
(African Journal of Food, Agriculture, Nutrition and Development, 2012-08) Ochieng, L.A; Mathenge, P.W.; Muasya, R.
Sorghum (Sorghum bicolor L. Moench) is an important crop that enhances food security in a region. As a food crop, sorghum is nutritious, containing starch (75-79%) as the major component, followed by protein (6.0-16.1%) and oil (2.1-5.0%). Despite the crop’s versatility, it is regrettable that sorghum yields are still fairly low in Bomet District of Kenya. One of the constraints associated with low yields is the accessibility to good quality seeds by farmers. It was assumed in this study that use of low quality seed was among the factors that could be significantly affecting the low production of sorghum in the district. This study focused on the physiological quality of seed which refers to the germination capacity, viability, characteristics related to dormancy and vigour of the seed. A total of 100 farmers were interviewed and 80 seed samples were obtained from 80 farmers. The seeds were subjected to viability and vigour quality tests. These tests included germination (as a viability test); mean germination time and electrical conductivity tests (as vigour tests). About 29% of the seed samples taken for germination test were below the laboratory standards as stipulated in the seeds and Plant Varieties Act (CAP 326). Critical electrical conductivity values and critical mean germination time values were derived during the study. In accordance with the critical values arrived at in this study, 27.5% of the seed samples showed relatively high electrical conductivity readings and 36.3% of the seed samples showed longer mean germination time. However, 11.3% of the seed samples showed high germination percentages of above 90%. Since about 29% of farmers seeds were of bad physiological quality, it was concluded that this proportion of seed can result in poor yields and hence cause food insecurity to the people of the society, and thus requires further consideration for improvement. This study recommends that further research be conducted on the genetic, physical and sanitary quality aspects of seed planted by farmers in Bomet District so that a definite conclusive statement about the quality of seed planted by farmers in the District can be made.
Biocontrol of Fusarium root rot in beans by antagonistic Trichoderma fungi
(International Journal of AgriScience, 2013-07) Muriungi, J.S; Mutitu, E.W.; Siboe, M.G.
Common bean (Phaseolus vulgaris) is one of the most important economic crop which is attacked by serious diseases such as Fusarium root rot. In this study, the efficacy of Trichoderma viride and T. koningii were evaluated for the suppression of Fusarium oxysporum causing root rot of beans in vitro and disease control under greenhouse condition. Three food carriers - broken dehulled rice grain, sorghum seeds, and vermiculite were also evaluated for suitability as growth and delivery media for Trichoderma isolates as determined by the sporulation ability and root rot control respectively. In vitro studies resulted in effective suppression of F. oxysporum by the two Trichoderma isolates. Saprophytic growth on rice and sorghum was good at two weeks but poor on vermiculite. T. viride in half broken dehulled rice produced excellent bean root rot control as measured by disease severity at 7th week and was significantly (P≤0.05) better than standard seed dresser Murtano (20% Thiram and 20% Lindane); T . koningii and T . viride in sorghum, and T. koningii in rice had moderate disease control whilst the two Trichoderma isolates in vermiculite had poor disease control. There was some positive correlation between saprophytic growth of Trichoderma isolates in different carriers in the laboratory and their suppression of Fusarium root rot in the greenhouse. The results of this study indicates that potential exist for management of Fusarium root rot in beans by antagonistic Trichoderma isolates in their respective carriers and may form part of IPM for bean root rot.
Biological control agents of aphids (Homoptera: Aphididae) on potatoes (Solanum tuberosumL) in Kenya
(2010) Machangi, J. M.; Gitonga, L. M.; Nderitu, J. H.; Maniania, N. K.; Kabira, J. N.
A field survey was conducted in four major potato growing areas in Kenya (Kiambu, Nyandarua, Meru and Molo Districts) during January and February, 2008 (short rains crop) and June 2008 (long rains crop) to determine the occurrence of predators, parasitoids and pathogens of the aphids Myzus persicae Sulzer and Aphis gossypii Glover in potato crops. In each of the four areas, 30 potato farms distributed in different parts of the survey area were selected at random for the surveys. Insects collected were brought to the laboratories at the International Centre of insect physiology and Ecology (icipe), Nairobi, for identification and fungal infection. For isolation of fungal pathogens, dead aphids were transferred on moist filter paper placed on sterile Petri dishes to allow the growth of the fungus on the surface of the cadaver, after which fungus was transferred on artificial media for isolation. Four aphid species, M. persicae, A. gossypii, Macrosiphum euphorbiae Thomas and Aulacorthum solani Kaltenbach were identified in all the four survey areas. Sixteen predator species of the aphids were identified. The most prevalent were the ladybeetles Harmonia axyridis (Pallas) and Hippodamnia convergens Guérin-Méneville (Coleoptera: Coccinellidae), followed by the minute pirate bugs, Orius spp. (Heteroptera: Anthocoridae) and the aphid eating gall midge Aphidoletes aphidimyza Rondani (Diptera: Cecidomyiidae). Three hymenopteran parasitoid species (Braconids followed by Chalcids then the Ichneumonids) and four fungal pathogen species, Beauveria bassiana Balsamo (Ascomycota: Hypocreales), followed by Verticillium lecanii Zimmermann (Hypocreales: Incertae sedis), Metarhizium anisopliae (Metsch.) Sorokin (Deuteromycotina: Hyphomycetes) then Pandora neoaphidis (Remaudière &Hennebert) Humber (Zygomycetes:Entomophthorales) were identified in all four areas of the field survey.
Biorational Preservation of Rose (Rosa hybrida L.) Cut-Flower Using Stevia (Stevia rebaudiana B.) and Thyme (Thymus vulgaris L.) Extracts
(SciPress Ltd, 2018) Kiige, John Kamanthi; Mathenge, Patrick Wachira; Kavoo, Agnes Mumo
Rose cut flower is one of the widely grown cut flowers in Kenya. However, most roses have a challenge of short vase life. This study aimed at determining the efficacy of plant extracts from thyme and stevia in preservation of rose cut-flowers. Two rose cut-flower cultivars; ‘radiance and ‘high & sparkling’ were subjected to stevia and thyme extracts each at three levels (0.2, 0.4, and 0.6gL-1). Thyme extracts at a concentration of 0.2 gL-1 significantly (p≤001) extended the vase life of rose cut flower by 3.5 days and floral absorption rates by 10.4% compared to the commercial preservative (chrysal) at the same concentration rates. Application of higher doses (0.4gL-1 and 0.6gL-1) of plant extracts led to shorter vase life (6 days) of rose cut flower and maximum bent neck records at day 8. The response of rose cut flower to the treatments did not vary between cultivars. The results from this study indicate that thyme extracts offer an attractive alternative to the use of chemical floral preservatives for prolonging the vase life and enhancing quality of rose cut flower. The efficacy of extracts is however depended on the concentration level with 0.2gL-1 dosage recording the best results.
Bradyrhizobium inoculation has a greater effect on soybean growth, production and yield quality in organic than conventional farming systems
(2021-06-22) Gitonga, Nicholas Mawira; Njeru, Ezekiel Mugendi; Cheruiyot, R. C.; Maingi, John
Globally, organic farming and bradyrhizobia inoculation are gaining popularity as agronomically and environmentally sound soil management strategies with great potential to alleviate declining soil fertility, maintain environmental quality and enhance soybean production. However, the role of bradyrhizobia in organic farming system is poorly understood. Field experiment was conducted to evaluate the effects of bradyrhizobia inoculation and organic farming on growth parameters and yield quality of soybean varieties: SC squire, SB19 and Gazelle. The experimental treatments included native bradyrhizobia, commercial Bradyrhizobium japonicum, mixture of native + commercial bradyrhizobia and uninoculated control. The experimental design was a split-split plot, with three replications. The results demonstrated significant improvement in soybean nodule dry weight (NDW), shoot dry weight (SDW) and seed dry weight (SEDW) following bradyrhizobia inoculation. Remarkably, organic farming significantly out-performed conventional systems in nodulation, SDW and SEDW. Moreover, seed nutrient content differed depending on farming system; where nitrogen, phosphorus, potassium and organic carbon were higher in organic farming. Soybean varieties differed significantly on SDW, NDW and SEDW; where SC squire performed better than SB19 and Gazelle. The results demonstrate the importance of organic farming and bradyrhizobia inoculation in enhancing soil fertility, yield production and quality, a key step towards sustainable food production.
Challenges and Opportunities in Tomato Production Chain and Sustainable Standards
(International Journal of Horticultural Science and Technology, 2020-04-23) Gatahi, Dennis Maina
Tomato(Lycopersicon esculentum) is an important member of the Solanaceae family. It is mainly used as food and cash crop globally. Tomato also serves as an ornamental plant in some parts of the world. In urban areas, thiscrop is included in the foodscaping systems where it is grown in hanging baskets, growing pots and aquaponics for aesthetic and food purposes. Tomato production is mainly done for fresh and processing market niches. Most developed countries process a larger portion of tomato than is offered in fresh form. Cultivation of tomato is practiced on the open field and inside greenhouses. Greenhouse production has gained popularity recently. Determinate varieties are produced outdoor while indeterminate ones are produced in greenhouses and tunnels. Due to good adaptability, heirloom tomato varieties are becoming popular especially where farmers practice tomato grafting using the indigenous varieties as rootstocks. High cost of inputs, pest and diseases, postharvest losses and marketing are the major challenges facingtomato production globally. Organic tomato production is an emerging market niche. This is due to the increased consumer awareness, environmental conservation requirements and globalization. Thus, farmers have been making strides towards compliance to organic and other sustainable standards. These standards require adoption of the requisite practices, documentation, verification and certification by a third party. Value addition in tomato is an important aspect in addressing the postharvest challenges, product diversification and ultimately profitability. Thisreview paper is expected to provide the requisite information in tomato value chain to ensure sustainable production of tomato globally.
Climate Variability and Adaptation Among Small Holder Banana Farmers in Mountain Regions of Kenya
(Geography, Environment, Sustainability,, 2021-04-01) Karienye, David K.; Nduru, Gilbert M.; Kamiri, Hellen W.
Banana production is the mainstay industry for majority of small holder farmers living in the mountain regions of Kenya. These regions are affected by climate-related impacts at all levels of the value chain. This paper therefore discusses climate trends, related impacts, and adaptations in banana value chain in Mt. Kenya region for the period between 1980 and 2017. The study locations were purposively selected from Mt. Kenya region to include both Imenti South and Mukurweini sub-counties. A sample of 381 respondents was selected using simple random sampling. Triangulation research design was used to guide the study by integrating both qualitative and quantitative methods in data collection and analysis. Historical document analysis was used to examine climatic data (temperature and rainfall) from the Kenya Meteorological Department, Nairobi. Results showed that rainfall and temperature have changed during the study period. Temperature trends in Mukurweini showed R2 = 0.3314 while in Imenti South R2=0.3441 with an overall annual increase in temperature in Mukurweini by 0.02°C while in Imenti South we registered an increase by 0.016°C for the study period. Mukurweini sub-county rainfall trend line had R2=-0.1064 while Imenti South sub-county had R2=-0.1014. Adverse effects of climate variability on banana value chain included low yields in both Mukurweini (79.2%) and Imenti South (60.2%) sub-counties. Farmers in the study area preferred irrigation (57.2%) followed by crop diversification (13.9%) as adaptive strategies to climate variability.