Department of Agricultural Sciences

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Evaluation of Ephestia kuehniella and Corcyra cephalonica as hosts for mass rearing trichogramma species nr. Mwanzai and trichogrammatoidea species nr. Lutea
(2008-01-16) Migiro, L. N.; Gitonga, L. M.; Sithanantham, S.
Production of vegetables free of chemical pesticides requires, among other things, use of biocontrol agents that can be effectively and efficiently produced in large quantities. Two factitious hosts were evaluated for their suitability in mass rearing of two native Trichogrammatids. Egg cards bearing host eggs were separately offered to female parasitoids in glass vials and allowed to parasitise for 24 hours. New egg cards were offered daily till death of the female parasitoid. The number of eggs parasitised, emerged adult progeny and female progeny differed significantly between the two parasitoids, with Trichogramma sp. nr. Mwanzai appearing to be superior to Trichogrammatoidea sp. nr. lutea.There were no differences in the mass production efficiency and quality of progeny between the Ephestia kuehniella and Corcyra cephalonica. The two hosts can be effectively used for mass production of either of the parasitoids.
Effects of induced mutagenesis and single backcrossing on agronomic traits of wheat (Triticum L.).
(2014-07-12) Obare, I. J.; Kinyua, M. G.; Kiplagat, O. K.
Induced mutagenesis has been extensively used to improve main crop species, particularly cereals including barley (Hordeum vulgare L).The main strategy in mutation-based breeding is to upgrade the well adapted plant varieties by improving a few desirable major traits such as yield component, tolerance to biotic and abiotic stress for consumer preferences. The present experiment was set out to determine the effects of induced mutagenesis on agronomic traits in mutant barley. The experiment was carried out in University of Eldoret research field in May –August 2012. One hundred and eighty three mutant lines were selected and used in the experiment with the parent (Nguzo) as a check. They were laid in a randomized complete block design with three replicates. The following parameters were used for the study; Number of tillers, plant height, a thousand seeds weight, spike length and days to 50% heading. The data obtained were analysed by Genstat software and mean separated by Duncan Multiple Range test. It was found that muta had a significant effect on number of tillers, plant height, weight of 1000 seeds, spike length and days to 50% heading at P<.001. From the results it is evident that mutagenesis had effects on agronomic traits in mutant barley lines hence can be used in creation of the much needed variation in breeding strategies in barley. The barley mutant lines that had superior characteristics in terms of the agronomic traits could be advanced and used in breeding programme or released as varieties.
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)
Evaluation of drought tolerance in mutant Kenyan bread wheat (Triticum aestivum L.) using in vitro techniques
(INNSPUB, 2016-08-31) Githinji, Gerald Gikonyo; Kinyua, Miriam; Kiplagat, Oliver; Birithia, Rael
Wheat (Triticum aestivum L) is widely cultivated as a small-grain cereal. In Kenya, it is ranked second after maize in its contribution towards food security. Biotic stress conditions such as drought cause extensive losses to agricultural production worldwide. In Kenya, arid and semiarid lands represent 83% of total land area, which experience frequent crop failure due to drought stress. Developing drought-tolerant wheat genotypes has been the focus of many wheat improvement programs. Few drought tolerant varieties are available for commercial production in Kenya. Hence, there is need to develop more drought tolerant wheat varieties. The objective of this study was to screen for drought resistance in two mutant wheat lines in vitro using Polyethylene Glycol (PEG). Four wheat germplasm were tested for drought tolerance using -3.0, -9.0 and -15.0 PEG-6000 concentrations and the data was recorded on various seedling parameters including root length, shoot length and root length /shoot length ratio. The experiment was carried out in three replicates using completely randomized design. Data was subjected to analysis of variance (ANOVA) using GENSTAT 12th edition. Correlation was done by Pearson Correlation Coefficients to determine significant associations among the different variables. Results indicated that there was a significant difference (p=0.05) between Mutant 1 and Mutant 2 having longer roots, shoots and a root to shoot ratio compared to Chozi and Duma in the different PEG concentrations used. Hence, the two mutant lines are possible candidates for varieties that can be grown in ASALs regions in Kenya.
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.
SEASONAL DYNAMICS AND ALTERNATE HOSTS OF THRIPS TRANSMITTED Iris yellow spot virus IN KENYA
(African Crop Science Society, 2018) BIRITHIA, R.K.; Subramanian, S.; Muthomi, J. W.; Narla, R. D.
Thrips-transmitted Iris yellow spot virus (IYSV) (Family Tospoviridae, Genus Orthotospovirus) is a major constraint to onion (Allium cepa L.) production in Kenya. Determining seasonal patterns of the vector and alternate hosts of the virus could help onion farmers plan Integrated Pest Management strategies; while allowing them to move away from calendar-based applications of insecticides. The objective of this study was to determine the distribution, seasonal variations and alternate hosts of vector and IYSV. For distribution, a survey was carried out on a network of farms in all onion growing areas in Kenya; while for seasonality, surveys were done in two areas; Loitoktok and Naivasha. Data were collected on IYSV incidence, thrips population and alternate hosts. Results showed IYSV was widely distributed in all onion growing areas; with incidence varying from 26 to 72%. Highest IYSV incidence was recorded during the cool-dry season, and varied from 56.5 to 71%; while lowest IYSV incidence in onions was observed during the cool and wet season (29.9 to 32.2%). Iris yellow spot disease incidence positively correlated with the number of onion thrips in Loitokitok (r = 0.659; P<0.0001) and Naivasha (r = 0.623; P<0.0001). Identified alternate hosts for IYSV were leeks, chives, shallots, lambsquarters, redroot pigweed, Chinese lantern and black nightshade.Occurrence of thrips on onions, which is grown all year round calls for urgent integrated pest management strategies that includes host plant resistance, field sanitation, forecasting and use of beneficial insects and parasitoids to reduce impact of the pest and disease. Plant health adherence through removal of alternate weeds hosts around the cultivated fields, would be useful in minimising IYSV incidence.
Effects of entomopathogenic fungus and spider plant intercrop in control of onion thrips and iris yellow spot virus
(INNSPUB, 2018-06-30) Birithia, Rael Kayume; Subramanian, Sevgan; Muthomi, James Wanjohi; Narla, Rama D.
Iris yellow spot virus (IYSV) is a major constraint to bulb onions production in Kenya. In search for alternative to synthetic insecticide, field experiments were conducted for two cropping seasons to evaluate the effectiveness of spider plant intercrop, Metarhizium anisopliae and carbonsulfan insecticide in the management of onion thrips and IYSV. Two onion varieties; Bombay red and Red creole were used. Randomized complete block design in a split plot arrangements was adopted. Results showed both varieties treated with entomopathogenic fungus recorded the least number of adult thrips while insecticide treated plots recorded the least larvae thrips. Insecticide, entomopathogenic fungus and intercrop significantly reduced IYSV incidence as compared to the control plots. Bombay red variety treated with fungus recorded the lowest severity and virus titer levels in the two cropping seasons. Adult thrips positively correlated with IYSV incidence in season one (r = 0.575; P <0.001) and two (r = 0.580; P <0.001). Red Creole treated with insecticide recorded the highest bulb onion total yield (10782.8 T/ha) and marketable yield yield (8314.8 T/ha) in the first cropping season. Entomopathogenic fungus treated plots outweighed other treatments in the second cropping season and recorded total bulb yield of 8503.7 T/ha and marketable yield of 7611.1 T/ha. Although, spider plant intercrop reduced bulb yield in both seasons, it contributed significantly in reducing onion adult thrips and increased food productivity. Metarhizium anisopliae and spider plant intercrops were found to be effective bio-pesticide and we suggest their inclusion in the integrated management strategies of vector thrips and IYSV.
Evaluation of drought tolerance in some Kenyan bread wheat (Triticum Aestivum L.) at seedling stage
(2019-11-02) Githinji, Gerald G.; Kinyua, Miriam; Kiplagat, Oliver; Birithia, Rael K.
Wheat (Triticum aestivum L) is the second largest contributor to food security in Kenya. However, water deficiency retards plant growth and productivity significantly. With few drought tolerant varieties available, there is need to develop more drought tolerant wheat varieties. Objective of this study was to screen for drought tolerance in the mutant wheat lines at seedling stage. Seeds of two wheat varieties were subjected to gamma radiation at an irradiation dose of 300 gy (gray). The mutants and two local varieties – Chozi and Duma (controls) were sown in polythene bags in a complete randomized design and screened for various seedling traits. Data were analysed using ANOVA and Pearson correlation. Results indicated that Mutant 1 and Mutant 2 had high emergence percentage, emergence index, energy emergence and per cent seedling recovery compared to local varieties Chozi and Duma. Emergency percentage showed a positive correlation with the following parameters; emergence index (r = 0.965); Energy of emergency (r = 0.990) and Percentage seedling recovery (r = 0.941). It was recommended that the mutant wheat be screened for other biotic and abiotic stresses that affect wheat production in Kenya.
Effect of Drying Method on Volatile Nutraceuticals and Microbial Growth in Moringa oleifera
(2021) Gatahi, Dennis Maina; Nyoro, Felix
Fresh Moringa oleifera leaves are very rich in phytonutrients, however the leaves are also highly perishable and require processing for increased shelf-life. The method of processing, specifically drying affects the nutritional value of the product. The present study therefore, analyzed the nutraceutical value and growth of toxic microbes when the leaves were dried under different conditions i.e. room temperature, greenhouse, 50% shade net, and in the oven at 60 oC for 4 h. The experiments were carried out at the Jomo Kenyatta University of Agriculture and Technology (JKUAT). The treatments were applied in triplicate and arranged on a completely randomized design (CRD). Data on nutritional value of dried Moringa leaves was subjected to analysis of variance (ANOVA) for parameterization and means separated using protected LSD0.05 . The study showed that drying Moringa leaves under shade, room and greenhouse conditions significantly (P <0.05) affects the nutritional value of the product. The results showed highest levels of vitamin C, vitamin A, polyphenols and terpenoids when the leaves were dried under 50% shade net and room temperature conditions. In contrast, the glucosinolate content was significantly (P<0.05) higher when the leaves were dried instantly in the oven (9.1%/wt), followed by drying under greenhouse conditions (8.7%/wt) before oven drying. However, drying of Moringa leaves under shade before oven drying resulted in growth of toxic microbial organisms such as staphylococcus, yeast, E. coli and molds that can potentially affect the safety of the product. Finally, the drying conditions also significantly (P <0.05) affected the moisture content of the powder obtained. The results of this study form an important reference for small-holder Moringa growers and processors in the development of an optimal processing regime for high value Moringa powder.
The effects of clonidine and yohimbine in the tail flick and hot plate tests in the naked mole rat (Heterocephalus glaber).
(Springer Nature, 2021-05-17) Mwobobia, R. M.; Kanui, T. I.; Abelson, K. S. P.
Objective: The naked mole rat (NMR) (Heterocephalus glaber) is increasingly considered an important biomedical research model for various conditions like hypoxic brain injury, cancer and nociception. This study was designed to investigate the effects of clonidine and yohimbine, an alpha-2 (α2) adrenoceptor agonist and antagonist respectively in the tail flick and hot plate tests. Results: A significant difference in tail flick latency was noted between saline control and 30 µg/kg clonidine, which was reduced after administration of 30 µg/kg yohimbine. A significant difference in hot plate latency was also noted between saline control and 30 µg/kg clodinine during the periods 30, 45, 60, 75 and 90 min after administration, and between saline control and 10 µg/kg clonidine during 30 min after administration. The hot plate latency by 30 µg/ kg clonidine was also reduced by 30 µg/kg yohimbine during 30 min after administration. Since the tail-flick and hot plate tests mediate the effects at spinal and supraspinal levels respectively, the present study indicates the presence and involvement of noradrenergic receptors in thermal antinociception at spinal and supraspinal levels of the NMR, similar to what has been found in other mammals.
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 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.
In Vitro Bioactivities of Commonly Consumed Cereal, Vegetable, and Legume Seeds as Related to Their Bioactive Components: An Untargeted Metabolomics Approach Using UHPLC–QTOF-MS2.
(MDPI, 2023-07-27) Aloo, Simon Okomo; Ofosu, Fred Kwame; Muchiri, Mary Njeri; Vijayalakshmi, Selvakumar; Pyo, Choi-Geun; Oh, Deog-Hwan
We conducted a comprehensive evaluation of the antioxidant, anti-obesity, anti-diabetic, and anti-glycation activities associated with the consumption of broccoli, red cabbage, alfalfa, and buckwheat seeds. Additionally, we explored the relationship between these biological activities and Citation: Aloo, S.O.; Ofosu, F.K.; Muchiri, M.N.; Vijayalakshmi, S.; Pyo, C.-G.; Oh, D.-H. In Vitro Bioactivities of Commonly Consumed Cereal, Vegetable, and Legume Seeds as Related to Their Bioactive Components: An Untargeted Metabolomics Approach Using UHPLC–QTOF-MS2. Antioxidants 2023, 12, 1501. https:// doi.org/10.3390/antiox12081501 Academic Editor: Stanley Omaye Received: 25 June 2023 Revised: 23 July 2023 Accepted: 26 July 2023 Published: 27 July 2023 Copyright: © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). the profiles of amino acids, polyphenols, and organic acids identified in the seeds. Our findings demonstrated that red cabbage, broccoli, and buckwheat extracts exhibited significantly higher antioxidant potential compared to the alfalfa extract. Moreover, buckwheat displayed the most signif icant capacity for inhibiting alpha-glucosidase. Remarkably, broccoli and red cabbage demonstrated substantial anti-glycation and lipase inhibitory potentials. We identified the presence of amino acids, polyphenols, and organic acids in the extracts through untargeted metabolomics analysis. Correlation analysis revealed that pyroglutamic acid positively correlated with all the investigated functional properties. Most polyphenols made positive contributions to the functional properties, with the exception of ferulic acid, which displayed a negative correlation with all tested biological activities. Furthermore, gluconic acid and arabinonic acid among the organic acids identified displayed a positive correlation with all the functional properties. These results strongly support the anti-diabetic, anti-obesity, and anti-glycation potential of red cabbage, broccoli, and buckwheat seeds.
Investigation of noradrenergic receptor system in anti-nociception using formalin test in the naked mole rat (Heterocephalus glaber).
(Elsevier Ltd., 2023-10-23) Mwobobia, R. M.; Kanui, T. I.; Abelson, K. S. P.
The naked mole rat (NMR) is a rodent that has gained importance as a biomedical research model for various conditions like hypoxic brain injury, cancer and nociception. This study was designed to investigate possible involvement of the noadrenergic receptor system in antinoception in the NMR, using the alpha-2 adrenergic receptor specific ligands clonidine (agonist) and yohimbine (antagonist) in the formalin test. Formalin test followed 30 min after intraperitoneal administration of ligands or control. A total of 96 naked mole rats were used. A significant reduction in nociceptive behaviours was demonstrated after administration of clonidine in the doses 1,3,10 and 30 μg/kg (n = 8 per group). Doses of clonidine above 30 μg/kg caused loss of motor and proprietion skills exhibited by prostration and failure to turn over when placed on their backs. The antinociception by 3 μg/kg clonidine was reversed by administration of 30 μg/kg of yohimbine. The present study demonstrates that the noradrenergic receptor system is present and involved in formalin test-related antinociceptive mechanisms in the NMR, similar to other mammals. Given the increasing importance of the NMR as a model for pain and nociception, the species may prove useful as an animal model for noradrenergic mechanisms in pain modulation.
Salinity tolerance, growth and survival of three Artemia franciscana (Kellogg, 1906) populations under laboratory conditions
(Wiley, 2024-04-17) Ngarari, Morine M.; Rugendo, Derrick G.; Nyonje, Betty M.; Hinzano, Sheban M.; Midumbi, David O.; Ngugi, Charles C.; Opiyo, Mary A.; Okalo, Francis A.; Gatune, Charles W.
In the 1980s, Artemia franciscana from San Francisco Bay (SFB) was introduced into Kenyan saltworks, where it has colonized and established stable populations. However, little is known about its biology, particularly with respect to its parental SFB population. This study compared the salinity tolerances of Kenyan (KEN) population, their SFB pro-genitors and those of Great Salt Lake (GSL) populations. Growth and survival of these A. franciscana populations were evaluated under varying salinity levels in a laboratory set up. A. franciscana nauplii were cultured at a rate of 1 nauplii/mL in 36 Erlenmeyer flasks and fed microalgae (Chaetoceros sp.) at 1.5 × 106 cells/animal/day for 8 days. Survival was evaluated daily and survivors were fixed in individual vials with Lugol solution. The total length of each fixed A. franciscana nauplii specimen was measured under a compound microscope. All populations were susceptible to salinities greater than 100 g/L. Compared with the parental SFB population, the KEN population exhibited significantly reduced survival and growth at 140 g/L, suggesting a narrower salinity tolerance range. These findings underscore the need for further studies focusing on other physiological parameters, abiotic factors and genetic characterization to confirm whether the KEN population is experiencing ecological adaptation. This will contribute to the optimization of Artemia practices in various salinity environments as a result of climate change.