Research Publications

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Screening for host plant resistance to Helicoverpa armigera (Lepidoptera: Noctuidae) in selected chickpea (Cicer arientinum L.) genotypes in Kenya
(24-04) Ruttoh, E. K; Mulwa, R.M.S; Ngode, L; Gohole, L; Towett, B.; Njogu, N. Silim; Kimurto, P. K.
Helicoverpa armigera is a major pest on the chickpea (Cicer arientinum) world. In Kenya, it causes up to 80% yield losses of the crop. Control measures include application of pesticides and cultural methods which have become less feasible due to their associated costs. Host plant resistance can offer long-term benefits in managing this pest. The objective of this study was to screen and identify chickpea genotypes that are tolerant to Helicoverpa armigera infestation under field conditions. Thirty chickpea genotypes were screened at Agricultural Training Centre, Koibatek under field conditions for two seasons in RCBD design in 3 replicates. Data on larval densities, percent pod damage, and amount of leaf consumed were transformed using angular transformation and then subjected to ANOVA, while treatment means separated using Duncan’s Multiple Range Test at P≤0.05. Correlation analysis between larval densities, yield and yield components was done using Genstat 12. The genotypes were classified into various categories of resistance and susceptibility on a visual leaf damage rating scale of 1-9. The results showed that there was significant variation in larval densities among the genotypes. At vegetative stage, mean larval densities ranged from 0.15 to 1.2 Genotypes EC583250 and EC583264 had lowest larval densities while ICC4973 and ICC3137 had highest densities. Larval densities increased from 0.3 to 1.97 during flowering stage. The larvae population increased drastically to a mean of 3.58 at podding. Genotype EC583260 had the least larval density of 2.2. The genotypes, EC583318, EC583250, EC583260 and EC583264 were least infested by the larvae with percent pod damage ranged from 3% on EC583264 with high yields while ICC3137 had highest pod damage of 20.2%. EC583260 was found to be low yielding (1051kg ha-1) while ICC4958 was the high yielding Egerton J. Sci. & Technol. Volume 13: 39-55 ISSN No. 2073 - 8277 (2205kg ha-1). Genotypes EC58318, ICCV10, ICC14831, EC583260, EC583264, and EC583250 had high resistance and could be exploited to chickpea breeding programmes as source to resitance.
Plant Regeneration via Somatic Embryogenesis from Leaf and Floral Explants of ‘Chancellor’ Wine Grape
(Egerton University, 2006) Mulwa, Richard M.S.; Norton, Margaret M.A.; Skirvin, Robert M.
Abundant embryogenic callus was obtained from leaf and floral explants of ʺChancellorʺ grape by continuous culture for 12 weeks on Nitsch and Nitsch basal medium supplemented with 9 μM 2, 4‐D + 17 μM IASP + either 1 μM BA or 1 μM TDZ (ECIM) in darkness. They were successfully maintained by a five to six week subculture interval on NN medium containing 2 μM 2, 4‐D + 0.2 μM TDZ + 4 μM IASP (LTMM). Near synchronous embryo developed from embryogenic callus on medium containing 10 μM IASP + 8 μM NOA + 1 μM TDZ + 1 μM ABA + 2.5 g/l AC (EDMM). Individually separated somatic embryos were germinated on both NN and half strength of MS containing 0.5 μM BA + 0.025 μM NAA, respectively; normal plantlet conversion from embryos was low (35%). Whole fruiting plants were obtained. Aberrant embryo development was characterized by failure to form functional shoot meristems following the initial cotyledon expansion during germination. These observations indicate that the embryo conversion stage of the regeneration is difficult and remains a limiting factor requiring more empirical experimentation for improvement in grape tissue culture.
Biotechnology approaches to developing herbicide tolerance/selectivity in crops
(Egerton University, 2006-01) Mulwa, Richard M.S; Mwanza, Lydia M.
Effective weed control in any crop production system is a prerequisite if high yields and good quality are to be achieved. Over the millennia that humans have practiced crop agriculture, weed control has been the most significant part of cropping operations in ensuring good quality harvests. Initially, hand weeding dominated most weeding practices but it was gradually replaced with mechanical control in the developed world. Mechanical weed control practices are now viewed to be unsatisfactory due to the high-energy requirements and other associated costs, plus the perceived facilitation of soil erosion and compaction. Mechanical weed control has now been largely replaced by chemical weed control using herbicides that can eliminate weeds from crop plantings with minimal soil disturbance. Herbicide treatment in crop plantings has allowed economically viable weed control and increased productivity. The most preferred herbicides today are those that combine weed killing potency with low- or no- environmental persistence. However, the very effective broad spectrum herbicides available also lack selectivity, thus limiting their use in some cropping operations. On the other hand, the continuous use of the few available selective herbicides is speeding up the development of herbicide resistance in weeds; hence making it difficult to achieve effective control in some crops. Herbicides generally function by disrupting unique and essential processes in plants e.g. photosynthesis, mitosis, pigment biosynthesis or essential amino acid biosynthesis. Both crops and weeds share these processes. Consequently, at present, selectivity is mostly based on differential herbicide uptake between weeds and crops, controlled timing and site of application or rapid detoxification of the herbicide by the crop plants. Reliance on these natural selective processes limits the effective use of potent herbicides; hence mechanisms to impart better herbicide selectivity in crops need to be investigated.
In vitro plant regeneration from immature cotyledon explants of macadamia (Macadamia tetraphylla L. Johnson)
(Egerton University, 2006-07) Mulwa, Richard M. S.; Bhalla, Prem L.
The macadamia tree, an Australian native, is highly valued for its nuts. Macadamia improvement pro- grams so far have relied on conventional breeding and selec- tion. The production of improved cultivars required to meet future demands could be accelerated by the application of modern biotechnological techniques, but this requires an efficient and reproducible regeneration system that has not yet been established for macadamia. We report here shoot regeneration from immature cotyledon explants of macadamia. Adventitious buds were induced on the cotyle- don explants from fruits collected at 140 and 190 days af- ter full bloom (DAFB) on MS medium supplemented with either 10 or 15 µM TDZ. The addition of 2% coconut milk (CM) to 10 µM TDZ containing media resulted in enhanced adventitious bud induction from 190 DAFB ex- plants. Further shoot development from the induced buds was depressed in media containing TDZ + CM; the addi- tion of 0.001 µM IAA to this combination doubled shoot development, from 1.9–3.9 shoots per explant. The trans- fer of bud clumps to media supplemented with 8.8 µM BA alone or in combination with either 0.14 µM GA3 or 0.001 µM IAA significantly increased shoot production from the previously induced explants by 1.5–2 times of that observed in TDZ + CM medium.
Assessment of clonal stability of in vitro regenerated shoots of Macadamia tetraphylla by RAPD analysis
(Egerton University, 2007) Mulwa, Richard M. S.; Bhalla, Prem L.
Macadamia nuts constitute an important part of the world nut industry and are highly valued for their health- promoting properties. Macadamia is an open-pollinated crop that takes 8–12 years to bear fruit when multiplied via seeds. The yield and nut quality in seedling plantations are often highly variable, and grafting is currently the most common method for producing nursery trees with reduced variability. We have previously reported on the tissue-culture propagation of macadamia, and in the present study we assessed the clonal integrity of the regenerated shoots. The RAPD proﬁles of 3 macadamia stock plants and 10 in vitro regenerated lines from each stock plant were analysed to assess the clonal integrity of the shoots regenerated in vitro for micropropagation purposes. The extent of genetic variation between the stock plants and 9 randomly selected seedlings was also assessed. There was no difference in clonal identity between the stock plants and their micropropagated progeny, indicating that clonal micropropagation was possible using enhanced axillary proliferation in macadamia. In contrast, there was a large genetic variation among the seedlings and between the seedlings and stock plants, with genetic distance estimates ranging from 0.121 to 0.637 among seedlings, indicating rampant out-crossing of the macadamia plant.
Structure, Conduct and Performance of Commodity Markets in South Sudan: Linkages Food Security
(Egerton University, 2008-07) Ngigi, Margaret
Several factor highlight food market risks and uncertainties for urban consumers in South Sudan. First, the South Sudan’s agriculture is yet to revive appreciably from severe disruptions caused by over two decades of civil conflicts. Secondly, rural and urban areas are poorly integrated, mainly due to a virtual absence of transport and communication infrastructures, as well as due to civil insecurities. As a result, major urban markets are heavily dependent on imports of most basic food staples. The major supply sources are North Sudan and Uganda. Khartoum and Kosti are the major centers of procurement transactions of North-South Sudan trade, while Kampala is the major centre of cross-border transaction of commodities flowing from Uganda. Together, North Sudan and Uganda account for the bulk of sugar, maize flour, rice, onion, wheat flour and sorghum sold in the four markets. This heavy dependence on importation of food supplies implies that any adverse events, both market and non-market, on the North- South Sudan, and/or the Kampala-South Sudan trade flows increases the vulnerability of a large percentage of urban households
Somatic Embryogenesis of Pathogen- Free Horseradish (Armoracia Rusticana) Plants in Vitro
(2009) Wannarat, Wannasiri
Illinois had been the major producer of horseradish in the United States for many years. Horseradish root production in Illinois had recently decreased due to a disease complex that causes root discoloration and rots. The use of pathogen-free (PF) horseradish planting stock was a means for the Illinois horseradish growers to restore root quality and yields. Micropropagation of PF plants through tissue culture could be used to deliver PF planting stock to growers, but it was time-consuming and has high labor costs. In addition, the growers needed millions of plants to supply their planting stock needs. It had been proposed to develop a method to produce whole plants from single cells via somatic embryogenesis. To initiate somatic embryogenesis, the Illinois Horseradish ‘Doll’ cultivar (‘Doll’) was tested with 2,4 -D (0.25 to 1.0 mg/l) and BA in vitro. Somatic embryogenic callus was successfully induced from leaf explants on MS medium supplemented with 2, 4-D. Somatic embryos (SEs) were collected from the callus, germinated, and converted to whole plants. Histological studies of SEs showed that they developed from cells near the vascular bundles. Furthermore, SEs developed through stages that mimicked normal embryo development. SEs germinated to give healthy and vigorous horseradish plants. Since cell suspensions of somatic embryogenic calli yielded plants, it raised the possibility to generate large number plantlets from suspension cultures. In addition, it was predicted that SEs could be encapsulated to make “artificial seeds” that could be used to supply a certified set program.
Production and Marketing of African Indigenous Leafy Vegetables
(Humbuldt Universitat- Zuberline, 2010) Henze, Judith; Abukutsa-Onyango, Mary; Opiyo, Arnold
PREFACE: It is unusual for young scientists to identify so strongly with the concerns and needs of their research subjects that they want to give them something substantial to help solve their everyday problems. Instead, it is common research practice that data on smallholder farmers’ livelihoods strategies, behaviour, and working conditions are extracted for research purposes, solely to be published in articles in high-impact scientific journals. In HORTINLEA interdisciplinary research programme, the 30 predominantly Kenyan, but also German and Tanzanian doctoral students agreed that they would not use their last summer term on statistics, scientific writing, or presentation techniques, but would use the term to hold a practical field day on AIV cultivation and marketing with and for smallholder farmers. This field day was intended to showcase innovative practices that are considered promising in applied research on production, socio-economics, marketing, and consumption of AIVs. In preparation for this field day, which took place in December 2018 in Bondo, the idea of a handbook to translate scientific findings to practical farm advice in farmer-friendly language was born. It was expected that rural advisory services and trainers could use the handbook to teach improved production and marketing practices for AIVs. The most practical and important knowledge gained over the course of their research was extracted,verified, and prepared from the research findings for inclusion in the handbook. The first draft was prepared by Judith Henze based on the expert knowledge of farmers, doctoral students, and their supervisors. These recommendations were peer-reviewed by two farmer groups to check for comprehensibility and identify knowledge gaps. Subsequently, the handbook was reviewed by scientists from Humboldt-Universität zu Berlin in the fields of soil fertility (Prof. Christof Engels), post-harvest management (Prof. Dr. Susanne Huyskens-Keil), and agricultural extension (Martin Ihm). A final review was conducted by Prof. Mary Abukutsa-Onyango from Jomo Kenyatta University of Agriculture and Technology (JKUAT) who has promoted farmer-friendly research in Kenya for many years and is a figurehead for the promotion of AIV crops in smallholder systems. Dr. Arnold Opiyo contributed to the concept of this handbook and gave it a final touch. It is an art and a challenge to derive sound recommendations for upgrading smallholder production and marketing practices from scientific findings. The handbook contains the main steps for upgrading the AIV value chain from sowing and planting, tillage, pest and disease management, irrigation and water management, harvesting, and post-harvest activities. These steps are complemented by information on how to keep farm records and where farmers may obtain further information in Kenya. With this handbook, the junior scientists have not only demonstrated their excellence in the scientific community, but proved that they strive for application- and transfer-oriented results with and for smallholder farmers. We hope the practical knowledge on agro-ecological intensification of AIV cultivation will be widely disseminated and that nutrient-dense AIV crops will be included frequently in daily meals to contribute to sustainable and healthy diets in Kenya and sub-Saharan Africa.
Characterization of Indigenous Chicken Production Systems
(Springer Science+Business Media, 2011-07) Okeno, Tobias O.; Kahi, Alexander K.; Peters, Kurt J.
Indigenous chicken (IC) and their production systems were characterized to understand how the whole system operates for purposes of identifying threats and opportunities for holistic improvement. A survey involving 594 households was conducted in six counties with the highest population of IC in Kenya using structured questionnaires. Data on IC farmers’ management practices were collected and analysed and inbreeding levels calculated based on the effective population size. Indigenous chicken were ranked highest as a source of livestock income by households in medium- to high-potential agricultural areas, but trailed goats in arid and semi-arid areas. The production system practised was mainly lowinput and small-scale free range, with mean flock size of 22.40 chickens per household. The mean effective population size was 16.02, translating to high levels of inbreeding (3.12%). Provision for food and cash income were the main reasons for raising IC, whilst high mortality due to diseases, poor nutrition, housing and marketing channels were the major constraints faced by farmers. Management strategies targeting improved healthcare, nutrition and housing require urgent mitigation measures, whilst rural access road network needs to be developed for ease of market accessibility. Sustainable genetic improvement programmes that account for farmers’ multiple objectives, market requirements and the production circumstances should be developed for a full realization of IC productivity. Keywords Characterization . Indigenous chicken . Production systems
Catechols in caffeic acid phenethyl ester are essential for inhibition of TNF-mediated IP-10 expression through NF-jB-dependent but HO-1- and p38-independent mechanisms in mouse intestinal epithelial cells
(Egerton University, 2012) Mapesa, Job O.; Waldschmitt, Nadine; Schmoeller, Ingrid; Blume, Carolin; Hofmann3, Thomas; Mahungu, Symon; Clavel, Thomas; Haller, Dirk
Scope: Caffeic acid phenethyl ester (CAPE) is an active constituent of honeybee propolis inhi- biting nuclear factor (NF)-kB. The aims of our study were to provide new data on the functional relevance and mechanisms underlying the role of CAPE in regulating inflammatory processes at the epithelial interface in the gut and to determine the structure/activity relationship of CAPE. Methods and results: CAPE significantly inhibited TNF-induced IP-10 expression in intestinal epithelial cells. Using various analogues, we demonstrated that substitution of catechol hydroxyl groups and addition of one extra hydroxyl group on ring B reversed the functional activity of CAPE to inhibit IP-10 production. The anti-inflammatory potential of CAPE was confirmed in ileal tissue explants and embryonic fibroblasts derived from TNFDARE/1 mice. Interestingly, CAPE inhibited both TNF- and LPS-induced IP-10 production in a dose- dependent manner, independently of p38 MAPK, HO-1 and Nrf2 signaling pathways. We found that CAPE did not inhibit TNF-induced IkB phosphorylation/degradation or nuclear translocation of RelA/p65, but targeted downstream signaling events at the level of tran- scription factor recruitment to the gene promoter. Conclusion: This study reveals the structure–activity effects and anti-inflammatory potential of CAPE in the intestinal epithelium.
Effect of Egg White Utilization on the Physico-Chemical and Sensory Attributes of Protein-rich Yoghurt
(2012-04) Gogoa, Lilian A.; Gogo, Kennedy O.; Shaloa, Peter L.; Mahungua, Symon M.
High protein yoghurt was made from whole milk, fortified with egg white (30% v/v) and skim milk powder at 12% (w/v). Different yoghurt mixes, with albumin content of 15%, 30% and 45% (v/v), were prepared. The control was made from whole milk, fortified with skim milk powder at 12% (w/v). The blended premixes were pasteurized at 74◦C for 4 seconds, cooled and then inoculated with 3% (w/v) Direct Vat Set yoghurt starter culture at 45◦C. After fermentation for 3 hours in a water bath maintained at 46±1◦C, product was cooled to 5◦C and then stored for 24 hours. The effect of the fortification on physico-chemical and sensory properties was investigated. Protein content increased to 8.50% at 45% egg white utilization. Susceptibility to wheying was reduced in egg-white fortified samples, without significant difference in sensory attributes of the test samples compared to the control. Sensory analysis showed that yoghurt fortified with 45% egg white was organoleptically acceptable. The yoghurt was rated as having better sensory appeal as compared to the control.
Analysis of an emerging peri-urban camel production in Isiolo County, Northern Kenya
(Camelid Science, 2012-05) Noor, Issack Mohamed; Bebe, Bockline Omedo; Guliye, Abdi Yakub
A study was conducted to analyse an emerging peri-urban camel production system in Isiolo County (northern Kenya), using the traditional pastoral camel production system as reference. Data was obtained from camel keepers through cross-sectional surveys in both systems, complimented by a focus group discussion with camel producers and camel milk. The results indicate that periurban camel production in Isiolo begun early 1990s and evolved to the present market-oriented production system. The gender of the majority of camel keepers in systems were males, however, there were more male camel owners in the pastoral system. Most camel owners in both systems had no formal/secular education (63.3 and 85.7 % for peri-urban and pastoral, respectively). Camels ranked as the most important livelihood source in both systems followed by sheep and goats. Milk for sale was more (P<0.01) important amongst camel keepers in peri-urban than in the pastoral system, whereas sale of progeny, transportation and socio-cultural roles were ranked important (P<0.01, P<0.001 and P<0.01, respectively) in the pastoral system. The majority (60%) of camel keepers within the peri-urban production system built their herds through purchase of foundation stock, whereas those (81.4%) in the pastoral system built theirs mainly through inheritance. The camel herd structures in the two systems were similar, except breeding males were higher (P<0.05) in the pastoral systems. The major constraints facing camel producers in both systems were camel diseases, inadequate feed resources and milk spoilage. The significance of these findings in the two systems is discussed. It is concluded that camel production in peri-urban areas near towns like Isiolo is gaining significance as an economic activity due to commercialization of camel milk. Keywords: arid and semi-arid lands, camel, Kenya, peri-urban
Analysis of an Emerging Peri-Urban Camel Production in Isiolo County, Northern Kenya
(Journal of Camelid Science, 2012-05) Noor, Issack Mohamed; Bebe, Bockline Omedo; Guliye, Abdi Yakub
A study was conducted to analyse an emerging peri-urban camel production system in Isiolo County (northern Kenya), using the traditional pastoral camel production system as reference. Data was obtained from camel keepers through cross-sectional surveys in both systems, complimented by a focus group discussion with camel producers and camel milk. The results indicate that periurban camel production in Isiolo begun early 1990s and evolved to the present market-oriented production system. The gender of the majority of camel keepers in systems were males, however, there were more male camel owners in the pastoral system. Most camel owners in both systems had no formal/secular education (63.3 and 85.7 % for peri-urban and pastoral, respectively). Camels ranked as the most important livelihood source in both systems followed by sheep and goats. Milk for sale was more (P<0.01) important amongst camel keepers in peri-urban than in the pastoral system, whereas sale of progeny, transportation and socio-cultural roles were ranked important (P<0.01, P<0.001 and P<0.01, respectively) in the pastoral system. The majority (60%) of camel keepers within the peri-urban production system built their herds through purchase of foundation stock, whereas those (81.4%) in the pastoral system built theirs mainly through inheritance. The camel herd structures in the two systems were similar, except breeding males were higher (P<0.05) in the pastoral systems. The major constraints facing camel producers in both systems were camel diseases, inadequate feed resources and milk spoilage. The significance of these findings in the two systems is discussed. It is concluded that camel production in peri-urban areas near towns like Isiolo is gaining significance as an economic activity due to commercialization of camel milk. Keywords: arid and semi-arid lands, camel, Kenya, peri-urban
Antimicrobial activity of the root extracts of Tylosema fassoglensis Schweinf. Torre & Hillc (Caesalpiniaceae)
(Egerton University, 2012-07) Adongo, John Onyango; Omolo, Josiah O.; Njue, Alice W.; Matofari, Joseph W.
Petroleum-ether, chloroform, and methanol extracts from Tylosema fassoglenssis (Caesalpiniaceae) were investigated for their in-vitro antimicrobial properties. A total of six microbial organisms belonging to five bacteria and one yeast species were studied using a disk-diffusion assay and minimum inhibition concentration (MIC) techniques. The result showed that none of the microorganisms tested was sensitive towards the petroleum-ether extract. The methanol and chloroform extracts exhibited anticandidal and antibacterial effects. Both the methanol and chloroform extracts, inhibited four isolates out of the five bacterial strains studied. The methanol extract showed a stronger antimicrobial activity than the chloroform extract judging from the sizes of inhibition zones. The minimim inhibition zones (MIC) of the methanol and chloroform extracts ranged from 125 to 250 µl/ml and 125 to 300 µl/ml, respectively. This study suggests that T. fassoglenssis, which is currently used in traditional medicine, is a potential source of antimicrobial compounds.
Production of Exopolysaccharides in the Kenyan Fermented Milk, Mursik
(IJSR, 2013) Muigei, Salome Chelagat; Shitandi, Anakalo; Muliro, Patrick; Bitonga, Ogata Rose
Exoplysaccharides (EPS) produced by Lactic acid bacteria (LAB) have attracted a lot of interest for application in production of healthy food products since LAB are food grade bacteria and their EPS are natural products. This research aimed to establish whether Mursik, a Kenyan traditional fermented milk product, contained Exopolysaccharides (EPS) and EPS producing Lactic acid Bacteria (LAB). Samples of Mursik were randomly collected from 39 selected homesteads in Njoro Kenya. EPS levels were isolated using alcohol precipitation method and quantified by phenol-sulphuric acid method. EPS producing LAB were screened using sucrose agar and identified by phenotypic and biochemical methods. The data obtained was analysed for variance and means separated by least significance difference. The findings indicate that EPS levels in traditional Mursik differ between households significantly (P< 0.05), and ranged between 17.86 - 59.77 mg/L glucose equivalent (Glu.equiv), average being 44.83 mg/L Glu.equiv. A total of 122 EPS producing LAB were isolated and characterized into five genera namely, Lactococcus (76%), Lactobacillus (11%), Enterococcus (7%), Leuconostoc (5%) and Weissella (1%). Their EPS yields in whey ranged between 44.3 and 449.9 mg/L Glu.equiv. Based on these findings it was concluded that Mursik contains EPS and a variety of EPS producing LAB, predominated by Lactococcus lactis species. It was recommended that Mursik should be developed and utilized as a functional food. EPS producing LAB from Mursik could be developed as starter cultures for improving rheological and functional properties of other fermented milk products.
Effects of lactic acid fermentation on sensory profile of orange fleshed sweet potato.
(Journal of Food Nutrition Sciences, 2013) Benard O. Oloo; Anakalo, Mahungu Symon; Maling’a Joyce Barasa
Green tea from purple coloured tea clones in Kenya- their quality characteristics
(Food Chemistry, 2013) Kilel, E. C; Faraj, A. K.; Wanyoko, J. K; Wachira, F. N
Analysis of microbial quality and safety of camel (Camelus dromedarius) milk chain and implications in Kenya
(Egerton University, 2013-02) Matofari, J. W; Shalo, P. L.; Younan, M., Nanua; Adongo, J. N.; Qabale, A.; Misiko, B. N
Camel milk is traditionally consumed raw by the pastoralists in Kenya. However, due to urbanization, population increase, search for alternative income sour- ces, and insecurity in the low lands where camels are concentrated, the demand for camel milk has increased. About 12% of the national milk in Kenya is camel milk. The bulk of it is sold raw in urban markets by informal milk traders (Field, 2001). Milk is an excellent culture medium for the growth of microorganisms. The rate of multiplication of microbes depends mainly on storage temperature and time, level of nutrients and handling conditions. The external sources of microbes include the equipment, the personnel and water. The ability of microorganisms to cause spoilage and disease depends upon the type present, the initial load of contamination of the milk, handling conditions and the time lapse from production before consumption (Bachmann, 1992). Common means of transporting camel milk in pastoral areas from production, about 10 to 20 Km away to bulking or market centres are bicycles, donkeys and occasionally vehicles. The ambient temperature in the production environment is about 39ºC. The milk reachesproduction environment is about 39ºC. The milk reaches the nearest bulking centres in 2 to 3 h and to major markets in cities in 6 to 8 h. The growth of contaminating microorganisms in raw milk therefore poses a threat to consumer health. The camel milk being marketed is of unknown microbial quality and safety to the public. This study investigated the microbial quality and safety and effect of developed acidity on microbial load along the chain of camel milk supply from production to the market. MATERIALS AND METHODS Sampling Composite samples of 10ml of milk were taken from the camel udder at production in the morning and evening at normal milking time. The samples were kept in a cool box maintained at 8-10ºC using iced accumulators. A total of 107 samples were collected at production. At bulking centres, 52 bulk milk samples were taken after pooling milk for storage or distribution to consumers or transportation to distant markets. Fifty nine (59) milk samples were collected from the city market and other sales outlets. All samples were transported to the laboratory within six hours.
Evaluation of SPAD chlorophyll fluorescence for on-site nitrogen assessment in drip fertigated sweet corn
(2013-04) Kitonga-Mwanza, Lydia L.M.; Swiader, John; Mulwa, Richard M.S.
This study was conducted over two growing seasons to evaluate the potential use of the Minolta SPAD-502 chlorophyll meter for rapid onsite determination of plant N status in a drip-fertigated nitrogen cropping regime of sweet corn. Four N fertilizer rates (0, 84, 168, and 336 kg N ha-1) were applied to two sweet corn cultivars (‘Kandy Plus’ and ‘Sugar Ace’) in a factorial split-plot design. Leaf SPAD and leaf total N concentration were measured at 4 different growth stages (seventh leaf stage (V7), tenth leaf stage V10), silking (R1) and milking (R3) in season one and three sampling stages (V6, V10 and R1) in 2002. In season two, leaf N concentrations and leaf ‘SPAD chlorophyll’ measurements increased early in the season up to silking (R1 growth stage) and declined thereafter. Leaf N concentrations and leaf SPAD readings were positively correlated. Critical SPAD values (readings associated with the lowest N fertilizer rate and providing the highest marketable ear yield) were estimated as 52.8, 52.1 and 59.0 at V7, V10 and R1 in season one; in season two the values were 51.0, 49, and 56.5 receptively. Regressing N rate on yield placed maximum ear yields at 13.8 tons ha-1 with 174.8 kg N ha-1 in season one and 9.7 tons ha-1 with 306.2 kg ha-1 in season two. Increase in leaf SPAD readings at silking reflects a strong sink/source relationship among leaves for absorbed N. The positive relationship between leaf SPAD readings and leaf N status is due to the responsiveness of SPAD-chlorophyll to N fertilizer application. These results indicate that the SPAD meter can be used effectively to assess sweet corn N status early in the season, and at this time it is possible to correct any N deficiencies that might compromise yields.
Development and Characterization of Wheat Germplasm with Combined Resistance to Russian Wheat Aphid and Stem Rust (Race “Ug99”) in Kenya
(Scientific Research, 2013-04) Amulaka, Fredrick O.; Maling’a, Joyce N.; Cakir, Mehmet; Mulwa, Richard M. S.
Wheat is the second most important cereal in Kenya. However, production is severely constrained by both abiotic and biotic stresses. Of the biotic stresses a devastating pest (Russian wheat aphid (RWA)) and a serious disease (stem rust race TTKS (“Ug99”)) are currently the biggest problem for wheat producers in Kenya. Severe infestations by RWA may result in yield losses of up to 90% while “Ug99” infected fields may suffer 100% crop loss. The two pests com- bined are seriously affecting wheat farmers’ incomes because of the heavy reliance on pesticides that increase the cost of production. This study attempted to develop and characterize wheat lines that are resistant to both RWA and “Ug99” by pyramiding two major resistance genes. Three wheat varieties: “Kwale”, a Kenyan high yielding variety but suscep- tible to both RWA and “Ug99”; “Cook”, an Australian variety carrying stem rust resistance gene Sr36 conferring im- munity to “Ug99”; and “KRWA9”, a Kenyan line with resistance to RWA but of poor agronomic attributes were used. A double cross F1 (DC F1) was obtained by crossing the F1 of “Kwale × Cook” and the F1 of “Kwale × KRWA9”. The DC F1 population was subjected to sequential screening for both RWA and “Ug99” resistance. Surviving DC F1 proge- nies were left to self pollinate to obtain the F2 of the double cross (DC F2). The DC F2 progenies were sequentially screened against RWA and “Ug99” to yield a population that was resistant to both RWA and “Ug99”. Genotyping of the DC F2:3 families were conducted to select homozygous resistant plants. Data indicated that the RWA and “Ug99” resistance genes were successfully pyramided. Though races with virulence for Sr36 have been reported, the gene pro- vides immunity to race “Ug99” and can still be effectively used as a component for “Ug99” resistance breeding together with other Sr genes.

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