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Recent Submissions
Performance of Interspecific Arabusta Coffee Hybrids for Yield, Cup Quality, and Disease Resistance
(2020) Cheserek, Jane J
The Kenya annual coffee production has in recent years declined due to different factors such as change of land use and biotic stresses, despite the country being one of the world’s producers of high-quality coffee. This study analysed the agronomic potential of Arabusta hybrids developed from C. arabica and C. canephora for their bean yield, quality, and disease resistance. Nineteen Arabusta genotypes were assessed in two different locations (Siaya ATC and KALRO-Alupe) for growth and bean yield during the second and third years after establishment in the year 2017 and 2018 respectively. The data collected and analysed included plant height, number of bearing primaries, percentage of berries per node, length of longest primary, the total number of berries on the primary, berries per node, laterals, nodes with the highest number of berries, berries per node and yield (g/tree). Genetic variability among the genotypes was determined using 19 SSR markers. Marker Assisted Selection (MAS) using SSR marker SAT 235 was used to identify genotypes with the Ck-1 gene that are CBD resistant. The polymorphism between the Arabusta genotypes and the Arabica coffee varied, with 72% polymorphism calculated among Arabusta genotypes and 46.8% among the Arabica genotypes. The SSR marker SAT 235 was able to identify genotypes that have the CK-1 gene for coffee berry disease resistance.
Genotypes and locations revealed differences that were significant for both growth and yield traits. There was a positive significant correlation between yield and percentage berries per node (r= 0.61), total number of berries on longest primary (r= 0.58), and total number of berries on each node on the longest primary(r=0.60). Arabusta hybrids that had higher yields when compared to other genotypes in Busia were ARH1, ARH4, and ARH5 whereas in Siaya it was ARH4. Significant variation in sensory and bean grade traits showed that Arabusta hybrids gave higher
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scores than backcrosses and Robusta. Acidity showed significant positive correlation with (r=0.96), aroma (r=0.84), balance (r=0.85), flavour (r=0.96) and preference (r=0.96). The 100 berry weight showed a positive correlation with the AA bean size indicating that berry weight can be used to predict AA bean size. Genotypes differed significantly in biochemical compounds across the two different environments.
The environmental effects were significant for all the biochemical compounds except for chlorogenic acids, but the G x E effects were not significant. The correlation between the chlorogenic acids and caffeine was significantly positive (r=0.77) but its correlation with lipid oil was significantly negative (r=-0.49) and also with sucrose (r=-0.43). Arabusta hybrids scored over 80 % for the total score in cup quality comparing well with the Arabica coffee and outperforming the Robusta coffee (79.4%) thus qualifying for the specialty market. Arabusta hybrids, backcrosses, and Arabica coffee on average had higher levels of sucrose, oil, and trigonelline when compared to Robusta which was responsible for the improved liquor quality.
This study confirmed that it is possible to transfer genes for high cup quality to Robusta from Arabica coffee through interspecific hybridization. The quantitative traits exhibited a highly significant positive correlation implying that these traits can be utilized in ensuring effectiveness and the efficiency of early selection for yield. The wider genetic variability of the Arabusta hybrids than that of Arabica coffee is key for coffee improvement programmes. All the hybrids and backcrosses did have the CK-1 gene responsible for CBD resistance. The Arabusta hybrids and the backcrosses had a score of > 80% on cup quality and therefore taking into consideration their performance in yield, the high yielding Arabusta hybrids ARH1, ARH4, and ARH5 are recommended for commercial cultivation in the specific environments.
DIGESTIBILITY, GROWTH AND ECONOMIC PERFORMANCE OF NILE TILAPIA (OREOCHROMIS NILOTICUS) FED ON A MIXTURE OF PLANT PROTEIN DIETS IN CAGES
(2020-08) ANNE MUNANIE MAUNDU
Fish feed is one of the critical components in aquaculture production and accounts for
over 60% of total operational costs with protein component being the most expensive
ingredient. Traditionally, fishmeal (FM) has been the primary dietary animal protein
source. However, with dwindling capture fisheries, FM has become increasingly
scarce and expensive due to its demand from human consumers and livestock feed
manufacturers. This in turn makes the cost of fish feeds expensive leading to low
profit margins in farmed fish. Therefore, there is need to identify alternative, low cost,
and nutritionally balanced sources of protein for the growth of the industry. Although
plant-based protein sources are viable alternative in replacing FM, there have been no
studies on mixture of plant proteins to establish their economic utility in fish farming.
This study evaluated the effects of replacing freshwater shrimp (caridina nilotica)
meal (FSM), with varying levels of soybean (Glycine max) meal (SBM), cottonseed
(Gossypium spp) meal (CSM) and sunflower (Helianthus annuus) meal (SFM) on
growth performance, digestibility, whole body composition and economic returns in
diets of Nile tilapia (Oreochromis niloticus). Fingerlings averaging 25g in body
weight were stocked in net cages installed in three 800m2 fertilized earthen ponds.
Each pond had 15 cages evaluating five diets with three replicates for a culture period
of six months. Three experimental set ups were designed to evaluate the efficiency of
a combination of SBM with other plant protein sources in replacing FSM in fish diets.
In trial 1, five isonitrogenous (30% CP) and isocaloric (3.5 kcal g-1
) diets were
formulated, substituting Fresh water shrimp meal with Soybean meal at rates of 0, 25,
50, 75 and 100%.Trial 2 similar diets as above were formulated replacing fresh water
shrimp meal with a combination of SBM, CSM and SFM at rates 0, 25, 50, 75 and
100%. In Trial 3, similar diets as in experiment 2 were formulated replacing FM with
a combination of CSM and SFM at rates 0, 25, 50, 75 and 100%. All fish were fed
twice daily at 10% of their body weight. Data were expressed as means and standard
error of the mean. Growth and proximate composition were analyzed using one-way
ANOVA at p< 0.05, and differences among treatment means identified using Tukeys
Multiple Range Test. Results from the study in trial 1, showed that fish fed on D0 had
higher final weight (p<0.05) than those fed on D1, D2 and D3, while D4 had the
lowest weight. In trial 2, fish fed on D1 showed growth performance that did not
differ significantly from fish fed D0. However, highest FM replacement (100%),
significantly (p<0.05) reduced growth performance. In trial 3, D0 and D1 had
significantly (p<0.05) higher mean weights than the rest of the treatments. In the three
trials, similar survival was observed among treatments, but digestibility of protein
decreased significantly (p<0.05) with increasing inclusion levels of PPSM in the diets.
In trial 1, the ash content of carcass decreased significantly with increased levels of
SBM. In trial 2, fish accumulated increasing levels of ash and crude fat with
increasing levels of PPSM. In trial 3, crude fat increased significantly across all
dietary treatments while ash content decreased with increasing levels of PPSM. Diet
D3 in trial 1 was more economically viable although it was not significantly different
(p>0.05) from D1 and D2. In trial 2 and 3, D0 and D1 were not significantly different
hence D1 was more viable because it was cheaper than D0. Based on these findings,
the present study concludes that the use of either pure fishmeal or fishmeal containing
a mixture of 25% of plant proteins diets leads to similar growth performance in O.
niloticus, the fishmeal containing the mixture of 25% plant proteins remarkably
reduces the production costs and achieves higher profits than when the pure fishmeal
is used. The present study therefore, recommends that for desirable net returns plant
proteins can be used in fish farming.
Sustainable Management of Organic Waste in Municipalities: PathwaystoBio-Energy, Bio-Fertilizer Production, and Climate Action
(Journal of Environmental Ecology, 2025-05-29) Mbugua J. Kamau, & Waswa G. Andati
Kenya’smunicipalitiesareexperiencingrapidurbanization,whichhasledtoasignificantincreaseinthegenerationoforganicwaste,particularlyfromslaughterhouses,open-airmarkets,andwastewatersystems.Poormanagementofthiswastecontributesheavilytoenvironmentalpollution,publichealthhazards,andgreenhousegas(GHG)emissions.Thisstudyinvestigatessustainablepathwaysformanagingmunicipalorganicwaste,withafocusonwaste-to-bioenergyandwaste-to-biofertilizersolutionsasintegralcomponentsofclimateaction.Thisresearchemphasizestheuntappedpotentialofanaerobicdigestionandcompostingtechnologiestoconvertslaughterandmarketwastesintovaluableenergyandagriculturalinputs.Italsoexaminestheroleofdecentralizedtreatmentsystemsinmitigatingmethaneemissionsandenhancingurbansanitation.GroundedinKenya'spolicycontextandsupportedbyrecentliterature;thestudyoutlinesthetechnical,institutional,andfinancialbarrierstoadoptingcircularwastestrategies.Itproposesamulti-stakeholderapproachinvolvinglocalgovernments,privatesectoractors,anddevelopmentpartnerstoimplementscalable,low-carbonsolutions.Thepaperconcludeswithtargetedrecommendationsaimedatimprovingsourcesegregation,promotingdecentralizedbiogasandcompostingsystems,enforcingwastewatertreatmentregulations,andunlockingclimatefinanceopportunities.Thesestrategies,ifwell-executed,couldtransformKenya’surbanwastelandscapeintoadriverofgreengrowth,publichealth,andenvironmentalsustainability
Post-harvest Practices of Maize Farmers in Selected Counties in Kenya and Isolation of Mycotoxin Producing Fungi from Maize Samples
(Ind. J. Pure App. Biosci., 2020-10-24) Mwancha S. N. Okioma, Eliud Mugu Gathuru, Isabel Nyokabi Wagara, Paul Njenga Waithaka and Benson Muriuki Githaiga
Mycotoxins produced by fungi are among the leading courses of human mortality and morbidity
all over the world. This study aimed at establishing the post-harvest practices that lead to
contamination of maize with fungi in Trans Nzoia, Kisii, Kisumu, Bungoma, Migori, Kericho,
Machakos, Kitui and Meru Counties in Kenya. The study was also aimed at isolating the most
common mycotoxin producing fungi from maize samples collected from the study areas. The
post-harvest practices were determined using a questionnaire. From each county, a total of 130
maize samples were collected. The samples from each county were mixed to make a composite
sample. The moisture content of the maize samples were determined and percentage moisture
content calculated. Each sample was ground using a dry mill kitchen blender (BL335, Kenwood,
UK). A sample of 1g was suspended in 9mL of sterile distilled water and serial dilution up to 10-2
carried out. A sample of 0.01mL was plated on potato dextrose agar. Mycotoxin producing fungi
were identified using morphological characteristics and fungal identification keys. The postharvest practices within the counties varied significantly. The mean moisture content of stored
maize varied from 16.78% in Kitui to 19.33% in Trans Nzoia. The number of mycotoxin
producing fungi ranged from 10.33 CFU/g in Machakos to 61.00CFU/g in Trans Nzoia. This
study established that the post-harvest practices observed in the study areas led to contamination
of maize with mycroflora. In addition, the moisture content levels of stored maize in the counties
favoured growth of mycotoxin producing fungi. There is need to identify the mycotoxins produced
by the mycotoxin producing fungi isolated in this study.
Assessing and Enhancing the Impact of Cotesia plutellae in Management of Diamondback Moth Plutella xylostella on Kale Brassica Oleracea var. acephala in Semi-Arid Areas of Kenya
(Journal of Environmental and Agricultural Sciences, 2017-06-30) R. Kahuthia-Gathu, M. Mwangi, M.O. Fiaboe
Diamondback moth (DBM, Plutella xylostella L.) is a major pest of crucifers
which can cause yield losses of up to 100% if left unmanaged. Classical biological control of
DBM was adopted in Machakos and Kitui County through Cotesia plutellae imported from
South Africa in 2002 and released in March 2004 in farmers’ fields where kale Brassica
Oleracea var. acephala is one of the major leafy vegetables. Preliminary studies in 2004-
2006 showed that the parasitoid had not established in the release sites and augmentation
releases were done in 2006. Monthly surveys were conducted (May 2012 to April 2013) to
assess the spread and contribution of C. plutellae in the management of the DBM. Brassica
oleracea var. acephala fields in twenty five randomly selected farms were sampled for
number of DBM larvae and pupae, damage, parasitism and parasitoid guild. The data was
recorded from 20 plants in each selected farm. The DBM larvae and pupae were placed in
plastic containers and taken to the laboratory for DBM or parasitoid emergence. Results
revealed that the mean number of DBM/plant in Kitui and Matuu ranged from 0.4 to 2.5 and
0.3 to 3.5, respectively. Mean damage score ranged from 1.2 to 1.6 in both regions, which
was positively correlated to the number of DBM on B. oleracea var. acephala.
Hymenopteran parasitoids recovered from DBM included Cotesia plutellae, Diadegma
semiclausum, D. mollipla, Apanteles sp., Chelonus sp., Oomyzus sokolowskii and Itoplectis
sp., while the hyper parasitoids included Mesochorus sp., Pteromalus sp., Notanisomorphella
sp., Eurytoma rosae and Eurytoma sp., Brachymeria sp. and Pediobius sp. Cotesia plutellae
was the most abundant parasitoid followed by D. semiclausum. Diversity of parasitoids
varied between months and study sites. Cotesia plutellae had established and spread beyond
the release sites contributing between 40 and 90% parasitism while the indigenous
parasitoids Itoplectis sp., Apanteles sp., and D. mollipla contributed less than 5% parasitism.
The results show the spread and establishment of C. plutellae in the study sites. In conclusion,
there is need for continuous training and educating the farmers to conserve the parasitoids
that have contributed in the reduction of the DBM and damage on the crop. This has
contributed in the reduction on pesticides use, spraying regime and eventual reduction of cost
of production and residues on the produce.
