CW-School of Agriculture and Enterprise Development

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Effect of a cowpea intercrop on maize yield and nutrient use efficiency in the coastal lowlands and semi-arid parts of Kenya
(1999) Mochoge, B. O.; Onwonga, Richard N.
To establish maize yield responses to N and P fertilizer and to manure, cowpeas were intercropped with maize in the drier zones of Kenya. The experiments were conducted over five seasons at six trial sites, in the coastal lowlands and in semi-arid parts of Kenya. M maize yields were significantly increased by the use of N and P and manure. Maize yields increased (P = 0.05) with the cowpea intercrop along the coastal lowlands, with increases ranging between 11 and 26%, while maize yields in the hinterlands were greatly reduced (18-36%), probably due to competition for environmental resources. Cowpea yields were generally low and unaffected by fertilizers or intercropping. The maize sole crop used N better than maize in the cowpea- maize intercrop, which in turn used P better than maize alone.
Promotion of Leguminous Plants and Organic Inputs for Improving Soil Productivity in smallholder Farms of Central Highlands of Kenya
(2002) Mugwe, J. N.
Declining soil and productivity is a major problem facing smallholder farmers in the central highlands of Kenya.This decline is caused by continuous cultivation of soils without adequate addition of external inputs in form of manure and fertilizers. Use of inorganic fertilisers is low due to high costs that are beyond the reach of majority of smallholder farmers. A multidisciplinary on-farm participatory was therefore initiated in the main maize growing areas of the central highlands of Kenya in 2000 with the main objective of addressing this problem. Results after four cropping seasons indicate that organic residues such as leguminous shrubs (Leucaena trichandra and calliandra calothrysus), herbaceous legumes (Crotalaria ochroleuca and Mucuna pruriens), Tithonia diversifolia, farm yard manure alone or with combination of 30 kg N ha-1 from inorganic sources can be used effectively to improve maize performance in the region.Over the four seasons under study, these organic residues gave an average mean maize grain yield in the range of 3.4 to 4.0 t ha-1 which is more than 1.0 t ha-1 that farmers in the area get from their farms. when the farmers were asked to select technologies that they wanted to test, majority selected tithonia, calliandra, leucaena and farm yard manure. This was attributed to availability of these organic resources at the farm level as tithonia could be cut along the roadsides and more than 80% of the farmers' own livestock. These results through preliminary, indicate that organic resources being tested in this trial are effective in improving maize yields and farmers are willing to try these on their farms
Nitrogen uptake and use efficiency as affected by soil organic matter status in Embu, Kabete and Maseno, Kenya
(2003) Mugendi, D.N.; Karunditu, M. W.; Kung'u, J.B.; Vanlauwe, B.
Nitrogen (N) is the nutrient most limiting to crop production and effective management is inevitable to minimizeits losses through the many pathways. Nitrogen uptake and use efficiency as affected by soil organic matter status (SOM)in the soil-plant system was studied in three sites located at Eastern, Central and Western parts of Kenya using 15N tracertechnique. Among the three sites calliandra treatment recorded the highest total yields (core, stover, and grain) in themicroplot that was labelled first (L) (17,205 kg/ha). Maize grain yields were observed to be highest again at PM1 trial incalliandra treatment in the microplot labelled first (L) (6,337 kg/ha). Among the three sites Embu recorded the highestuptake and use efficiency in calliandra treatment in the microplot labelled second. The observation made in calliandracould be attributed to its low quality (slow decomposition and N release) hence its ability to build up SOM
The status of fungal tuber rots as a constraint to cassava production in south Cameroon
(2004-11-05) Mwangi, M.; Messiga, A. J.; Bandyopadhyay, R.; Nolte, C.
Fungal rots have been reported as a limiting factor to cassava production in the humid forests of Central and West Africa. Starting April 2003 tuber rots were studied for one year as part of a diagnostic survey designed to investigate biophysical and crop management factors limiting cassava production in Pouma district, located halfway between Douala and Yaoundé in Cameroon. This paper reports the extent of root rot occurrence in the study area comprising of 62 farmer-managed trials. Root rot data was recorded at 6, 9, and 12 months after planting (MAP). At each sampling time samples of rotten tissue were collected for isolation and identification of the fungi. At 6 MAP, 41% of the field plots were free from rot symptoms and only little rotting was observed in 55% of the field plots. However, at this early stage of tuber development, more than 50% of root volume was rotted in nearly 2% fields. At 9 MAP rotting incidence and severity had substantially increased as compared to 6 MAP, but still only about 2% of the fields had up to 50% of the root volume rotted. At 12 MAP rot incidence was less than at 9 MAP, but severity had substantially increased with tubers in 11% of the fields having up to 25% of their total volume rotted. Pathogens isolated from rot specimens include Botryodiplodia theobromae, Macrophomina phaseolina, Fusarium sp., Armillaria sp., Aspergillus sp., Sclerotium rolfsii and Trichoderma sp. Data obtained indicate that fungal rots could cause substantial loss to cassava production in the Pouma area. However, the loss is less if cassava harvesting is done at 12 months.
The role of nitrogen forms on solubilisation and utilisation of rock phosphate by tomato plants
(African Crop Science Society, 2005) Onyango, Gweyi; Neumann, G.; Romheld, V.
The role of nitrogen forms on solubilisation and utilisation of rock phosphate was investigated on tomato (Lycopersicon esculentum) crops grown in minirhizotrons to assess root-induced chemical changes in the rhizosphere. Two tomato cultivars Cal-J and Moneymaker were supplied with rock phosphate as P source, ammonium (plus DIDIN-nitrification inhibitor) and nitrate as Nforms.NH4+ treatment significantly reduced rhizosphere pH while nitrate led to alkanization. Shoot P content increased with declining rhizosphere pH due to rock phosphate solubilisation. P nutrition was sufficient for NH4-N (intense rhizosphere acidification) but critical under NO3- supply. Shoot Ca contents were in the deficiency range under NH4+ supply, despite increased Ca availability due to rock phosphate solubilisation. Also Mg2+ and K+ uptake declined with decreasing rhizosphere pH. These findings suggest NH4 + and H+ competition with cation uptake, limiting shoot growth. Acid soils low in Ca and Mg, NH4 + in combination with NO3- may improve rock phosphate utilisation
Genetic biodiversity assessment and local seed systems of maize landraces among smallholder farmers in Western Kenya
(African Crop Science Society, 2005) Muui, C. W.; Anjichi, V.E.; Muasya, R.M.; Gohole, L.S; Rao, N.K.
Maize is the main staple food in Kenya and adoption rates for improved varieties is high. Smallholder farmers grow over 75% of the maize crop in Kenya. Breeders consider that some local varieties hold potential value for local adaptation and other useful traits. Many farmers in western Kenya use local maize landraces although documentation indicating genetic diversity of these maize types has not been done. The objective of this study was to assess the genetic diversity of these local maize landraces and to document the existing local seed systems of the same in four western Kenya districts. A total of 285 randomly selected farmers from four western Kenya districts were interviewed using a questionnaire. Both primary and secondary data is used. Four maize landraces were found in this region. Eighty percent and sixty five percent of farmers in Siaya and Busia districts respectively planted only these maize types, whereas Bungoma and Kakamega each had 32% and 20% respectively. These local maize types covered more than half of the total maize area in Siaya and Busia districts. The interviewees had a well defined local maize seed system. In conclusion there are four types of indigenous maize types of economic importance in western Kenya with well defined seed conservation systems. It is recommended that communities in the lower potential areas of Siaya and Busia districts be considered as sites for improved on-farm seed conservation programmes. Also, any anticipated introduction of genetically modified maize into this region should be done under carefully considered guidelines to minimize the risk of contaminating these maize types.
Use of leguminous shrubs for soil fertility improvement in sub-humid highlands of Kenya
(2006) Mugwe, J. N.; Mugendi, D.N.
Declining crop productivity is a major challenge facing smallholder farmers in central highlands of Kenya. This decline is caused by continuous cultivation of soils without adequate addition of external inputs in form of manures and fertilizers. With this background, an on-station trial was initiated at Embu in 1992 to evaluate the feasibility of using two leguminous shrubs; Calliandra calothyrsus and Leucaena leucocephala for improving soil fertility and food production. The results obtained so far indicate that, over the 12 years of study, calliandra biomass transfer with half recommended rate of inorganic fertilizer treatment gave the best average yield of 3.3 Mg/ha followed closely by leucaena biomass transfer with half recommended rate of inorganic fertilizer treatment with an average of 3.2 Mg/ha. However, calliandra alley cropped treatment with prunings removed recorded the lowest maize yield of 1.2 Mg/ha over the same period. Though treatments with calliandra biomass transfer had similar yields compared to those of leucaena biomass transfer, all the treatments that were leucaena alley cropped did better (significantly different) than calliandra alley cropped treatments both with prunings incorporated and prunings removed. This could be attributed to the more intense root competition of calliandra with maize compared to leucaena whose greater percentage of roots are located below the effective rooting zone of the maize crop. Overall, treatments with prunings incorporated with half recommended rate of inorganic fertilizer gave better maize grain yields compared to treatments with only prunings applied.
Economic Evaluation of Locally Available Inputs for Soil Fertility Replenishment in the Smallholder Farming Systems of Meru South District, Kenya
(2006-07) Mucheru-Muna, M.; Mugendi, D.N.
Declining land productivity is a major problem facing smallholder farmers in Kenya today. This decline is a result of reduced soil fertility status, which is caused by continuous cultivation of soils without adequate addition of external inputs in form of manures and fertilizers. The low soil fertility contributes enormously to one of the greatest challenges facing farmers in the central highlands of Kenya currently; the inadequate food production for the rapidly growing population. A farmers' participatory trial was established in Meru South District, Kenya in 2000 with the main objective of offering poor resource smallholder farmers feasible soil nutrient replenishment technologies. The results across the seven seasons indicate that, sole tithonia gave the highest grain yield followed closely by tithonia with half recommended rate of inorganic fertilizer with 6.4 and 6.3 Mg/ha respectively. Control treatment gave the lowest yield of 1.5 Mg/ha across the seasons. The integration of organic and inorganic nutrient sources of N gave higher maize grain yield as compared to the sole application of organic materials during the seven seasons of the study. Results of the economic analysis indicate that, on average across the seven seasons, tithonia with half recommended rate of inorganic fertilizer recorded the highest (USD 787.2) net benefit while control recorded the lowest (USD 271.7). On the other hand recommended rate of inorganic fertilizer gave the highest (USD 12.5) return to labour while sole tithonia gave the lowest (USD 4.0). On average in the farmers' fields, manure alone gave the highest return to labour of USD 3.6, while the control treatment gave the lowest return to labour of USD -0.2. Despite the fact that tithonia had the lowest return to labour in the demonstration site, most farmers in the study area were willing to try it in their farms. This could be due to its to local availability and the low opportunity cost of farmers' time.
Soil fertility management using organic and inorganic inputs in the central highlands of Kenya
(2008-11) Mugwe, J. N.; Mugendi, D.N.; Mucheru-Muna, M.; Merckx, R.; Vanlauwe, B.; Karega, R.; Muriuki, J.
An integrated soil fertility management (ISFM) initiative was started in the central highlands of Kenya in 2003 with an objective to introduce, evaluate and promote adoption of ISFM technologies with farmers’ participation. Participatory approaches were used to test and disseminate the use of organic and inorganic inputs during the period 2003 to 2005. This study was carried out to assess farmer attendance in project activities, testing levels of the various inputs, maize yield response to soil fertility inputs and farmers experiences as they tested the inputs. Data on participation were collected from secondary data while on-farm trials, a household survey and focused group discussions were used in collection of primary data. Results showed that more males than females participated in most meetings but the participation of women was encouraging and improved with time. An integration of organic and inorganic inputs was tested by most farmers. However farmers also had their own modifications that combined different kinds of organic materials. Use of the inputs increased maize yields at the farm level by more than 150% above the control. When the inputs were ranked by farmers, in terms of overall benefits, gender differences were observed with female farmers preferring materials that would be within their reach such as calliandra, while male farmers preferred fertilizer possibly because they could afford to purchase it. This study has demonstrated that the use of organic materials by farmers (calliandra, leuceana, tithonia and manure) combined with inorganic fertilizer has potential to address the low soil fertility problem in farmers fields and raise yields. There is a clear need of strategies and policy that address gender disparities in adoption of soil improvement technologies.
Potential role of corporate social responsibility in poverty alleviation among contract sugarcane farmers in the Nzoia sugarbelt, Bungoma, Kenya
(Kenyatta University, 2009) Waswa, F.; Netondo, G.; Maina, L.; Naisiko, T.; Wangamati, J.
Although introduction of contract sugarcane farming was expected to alleviate poverty through increased income to farmers, it is widely acknowledged that poverty levels in western Kenya are still high. While the sugar companies generally register super profits, the surrounding communities, who supply the labour and land for cultivation of the sugarcane, are yet to break out from the poverty ratchets. Results from a study done within the Nzoia Sugarbelt in 2007 indicated that food insecurity and poverty remain serious concerns largely because most of the land is dedicated to sugarcane farming at the expense of other important food crops. In addition income generated from sugar processing is unevenly shared in favour of the company and not the farmers whose land and labour is contracted for this' purpose. To bridge this gap and enhance community livelihoods, this paper argues strongly for the need to institutionalise Corporate Social Responsibility policies within the daily operations of the company. Ten key building blocks for such a policy for Nzoia Sugar Company are suggested based on research findings from the field.
Evaluating health of macropropagated banana seedlings
(2010) Kahuthia-Gathu, R.; Njau, Njeri; Mwangi, Maina
Objective of study: Banana (Musa spp.) is one of the most important food and cash crops in parts of Kenya. The crop provides food security, nutrition and income for many smallholder farmers. Bananas can be eaten fresh, cooked or processed into numerous value added products, depending on the variety. Despite the importance of the crop, it faces major production challenges including scarcity of high quality seedlings, insect pests and diseases. Naturally produced suckers are more likely to carry pests and diseases leading to reduced productivity and shortened lifetime of new plantations. Demand for disease free high quality planting materials has been on the increase. To address this demand macropropagation has been introduced as an alternative seedling production technology. The technology requires little capital and skill to implement, and can therefore be promoted to small scale seedling entrepreneurs and farmers. However, some aspects of the technology require further research to ensure quality of seedlings. This study is being carried out to establish the effectiveness of macropropagation technology to produce disease free banana seedlings. Methodology: The study will commence with a survey to identify the key diseases and insect pests of bananas in Eastern and Central Kenya. Macropropagation nurseries for research will be established at Kenyatta University. Pests and pathogens will be isolated from banana corms and their importance in health of seedlings determined through pathogenicity tests. Expected outputs: The information obtained through the study will contribute to improvement of the macropropagation protocol to ensure the propagated seedlings are free from pests and pathogens
Decomposition and Nitrogen Release Rates of Buried Chickpea (Cicer arietinum L.) Residue in a Mollic Phaeozem of Njoro, Kenya
(2010) Mochoge, B. O.; Onwonga, Richard N.; Nakhone, Lenah; Musandu, Amos O.; Lelei, Joyce J.
Synchronization of nutrient release from organic material and nutrient uptake requires a better understanding of plant residue decomposition kinetics. A field experiment was consequently conducted, at field 7 research station of Egerton University, to determine chickpea residue decomposition and N mineralization rates. Fresh chickpea residue, weighing 50 g, was placed in each of the fifteen 7 mm-mesh litterbags measuring 25 × 25 cm. The litter bags were arranged in a randomized complete block design and buried horizontally in the plough layer with five bags per replicate. One bag was randomly retrieved from each replicate after 10, 20, 30, 60 and 90 days. Dry weight of the residue was recorded after oven drying at 70_C for 48 hours. The decomposition (KD) and N release (KN) rate constants were estimated using a single exponential model Yt = Y0 ×e-kt; where: Y0 is the original amount of material applied and Yt the proportion of the initial dry matter or N remaining after a period of time t, in years. The K value was the slope of the linear regression of l_Y verses t. The chickpea residue initially decomposed rapidly with 67% of the original weight being lost within the first 30 days and 80, 94% by 50 and 90 days, respectively. On a logarithmic scale, the calculated KD was -11.05 year-1 and 20 days were required for 50% loss in dry weight. Nitrogen released from the residue followed the same trend as dry weight loss. The calculated KN of the chickpea residue was -3.11 year-1. The cumulative N mineralized, in 30 days, was 18.9 g kg-1 (58%) out of the 32.4 g kg-1 contained in the residue before incorporation in soil. To synchronize nutrient release and nutrient demand, the chickpea residue incorporation should therefore be done closer to planting to benefit the subsequent crop.
Studies on the die back disease of passion fruit in major production areas in Kenya
(2010) Kahuthia-Gathu, R.; Wangungu, C.W.; Mwangi, Maina
Passion fruit is an important horticultural crop in Kenya where it is grown widely by small scale farmers primarily as a source of income. The fruits are supplied to the local and export markets where they are consumed as fresh fruit for its nutritive value or utilized for commercial processing purposes. Passion fruit is a good source of flavanoids that have important medicinal value. Presently, demand for the fruit greatly exceeds supply; and this trend is project to persist in future, especially due to the emergence of new large scale producers of beverages using locally available fruits, among the passion fruit. The downward trend of passion fruit production which has brought the industry to a near collapse is mainly attributed to pests and diseases. A number of fungal diseases have been identified as the major constraints to production. These include Fusarium wilt and a recently emerged but highly severe disease attributed to a complex involving Phytopthora species. Compared to Fusarium wilt, the die back disease is rather poorly understood. Since the disease is fairly new in the major passion fruit production areas in Kenya, no effective management strategies have been developed as yet. Preliminary research is yet to conclusively determine whether the disease is caused by a single or multiple organisms, though some reports suggest it is a complex caused by several pathological organisms, possibly involving viruses l and fungi. This proposed research will aim to generate data to fill the existing knowledge gaps and thus contribute to the development of effective control methods. Field studies will be carried out in the major passion fruit growing areas in Central and Eastern provinces of Kenya in Meru, Embu and Thika districts. Disease incidence and severity will be recorded and infected plant samples will be collected for isolation and identification of the causal organism(s) in the laboratory. Several trials will be carried out under controlled environment to establish pathogenicity of the isolated organisms on healthy passion fruit plants. A combination of disease control methods will be investigated. The data generated will contribute to improved understanding and more effective management of the dieback and other diseases threatening the Kenyan passion fruit industry.
Banana Farming in Kenya: Options for Rejuvenating Productivity
(Ruforum, 2010) Mwangi, M.; Mbaka, J.; Adipala, E.; Tusiime, G.; Majaliwa, J.G.M.
Bananas constitute an important component of farm enterprises in the mid altitudes of central and eastern provinces of Kenya. In recent years the crop has steadily gained importance over traditional cash crops, e.g. coffee, and various short season horticultural crops grown mostly for export markets. Despite its increasing importance, the crop’s production faces intractable constraints. Interventions have previously focused on increasing availability of healthy seedlings and strengthening farmer capacity to manage pests. Recent indications are that there is need to re-think current approaches to enhancing productivity. Interventions should consider creating micro-financing and value addition opportunities, and extending technologies to cope with climate change effects.
Soil properties effects and management of organic residues to improve C sequestration, reduce N losses and improve crop yield
(2010-09) Mugwe, J. N.; Danga, B. O.; Mochoge, B. O.; Getenga, Z.
Rates of decomposition of organic materials in soil determine the amount of carbon (C) which is mineralized and released as CO2 versus the amount of C that is retained in various forms in the soil. Decomposition rates also greatly influence the amount of nitrogen (N) which becomes available for plant uptake or susceptible to leaching versus that which is retained in SOM or lost via gaseous emission. The processes that follow the decomposition of residues by microorganisms are strongly influenced by soil chemical and physical properties, and also by plant roots via the processes of mineral N uptake, respiration, exudation and decay. The equilibrium between carbonates, bicarbonates, CO2 and pH controls inorganic C losses and deposition over large areas of arid and semi arid climates and should be linked to the biological cycle of C. However, few quantitative relationships between decomposition rates of organic manures & wastes (OW) and controlling edaphic, climatic and biotic variables have been determined. The overall objective of this proposal is to explore the effects of soil properties and management practices on C sequestration in soils, off-site losses of N and crop productivity. We hypothesized that organic waste decomposition is a biological process controlled by the microorganism population and it is not affected by soil properties, and that sequestration of CO2 -C by inorganic components of the soil may be a considerable process in calcareous soils. The methodology includes the simultaneous use of laboratory and field experiments with stable isotopes of N and C to follow the dynamics of N and C. Best management practices will be identified by field experiments and simulation scenarios with the process oriented computer simulation models of N and C transformations in a soil-OW-plant system (NCSOIL) and two MSc students will be trained.
Impacts of agricultural trade and market liberalization of food security in developing countries: comparative study of Kenya and Zambia
(2010-09) Nyairo, N.M.; Kola, Jukka; Sumelius, J.
The introduction of agricultural reforms has debatable effects on food security in developing countries. This research investigates how such effects influenced maize supply in two developing countries which were among the first to introduce agricultural reforms. Conclusions from the research suggest that agricultural reforms led to mixed results. This may be attributed to the sometimes stop-go nature of reform implementation. The mixed results are reflected in the weak maize output response to price changes. Overall country economic conditions, state of agricultural development can be attributed to the pace of response, hence effect on agricultural supply. Elasticity of maize output to changes in price and acreage are strongly significant in maize output for the case of Kenya. Both restricted models of maize production suggest that prior to the introduction of reforms acreage, prices and alternative crops were more elastic when simulated with Zambian data than with Kenyan data.
Improving soil nutrients and water management to increase crop yield for enhanced livelihoods of small scale farmers in semi-arid eastern Kenya
(2010-09) Mochoge, B. O.; Danga, B. O.
Food insecurity in Kenya is on the increase unless appropriate measures are taken. This is because nearly 80% of the land is arid to semi-arid and therefore not favorable for crop production using the current methods of production. The issue is limited nutrient use efficiency and low moisture storage in soils to warrant plant growth. This calls urgently for appropriate technologies to be put in place in order to increase moisture storage in soils and increase nutrient use efficiency to spur food production in semi-arid fragile ecosystems. A study to respond to low moisture content in soils and inefficient use of nutrients is being initiated at Gachoka, semi-arid Eastern Kenya. The study will evaluate moisture storage in soil due to run-off rain water captured in the trapezoidal bunds and how this will impact the availability and uptake of nutrients. Use of manure to increase water retention in soils and to provide mineral N through mineralization, and application of N and P fertilizers to supplement the soil available nutrients for sustainable soil fertility management will be part of the treatments. Plots within the bunds measuring 4.5 m x 4.5 m will be used for treatments and maize and cowpea will be the test crops. Available soil moisture content will be measured using neutron water meter and tensiometers while available plant nutrients (NH4,NO3 and P) in soil and nutrients contents in plants will be analyzed. Treatments will be factorial and randomized in a complete block design. The data will be subjected to analysis of variance and regression. Nutrient use efficiency and gross returns will be calculated. Expected outputs will include increased knowledge on trapezoidal bunds on water storage by researchers and farmers, higher crop yields, general increase of soil productivity and its sustainable management, and training of two MSc students.
Effects Of Substituting Maize With Rice-milling By-products In Commercial Layer Chicken Diets
(2011) Kabuage, L.; Njuguna, K.W.; Maina, J.G.
Inadequacy of high quality and reasonably priced poultry feeds constitute major challenges to the development of a vibrant poultry industry. Maize and its by-products are the main energy sources used in the manufacture of commercial poultry diets. Maize has an energy content of 3550 ME kcal/kg compared to the more abundant broken rice (BR), fine bran (FB) and coarse rice with 2980, 2990 and 2650 ME kcal/kg respectively. Maize, the staple food for most Kenyans is expensive and only limited quantities are available for feed manufacturing, hence the need to explore cheap alternative energy sources. BR and FB are produced by the multi-step rice milling process, while the single step milling process leads to the production of a single combined byproduct (SCB), all studied in this research. One hundred and forty ISA brown layer chickens were distributed to five treatments in a completely randomized design. They were housed in battery cages at the University of Nairobi Poultry Unit from onset of lay to the peak of the laying cycle. Three test diets containing rice by products and two control diets constituted by a commercial layer mash and a maize soya bean basal diet were evaluated. The test diets contained 60% BR during the first eight weeks and 40% over the subsequent eight week period; SCB graded at 0, 5 and 10 %, while FB was fixed at 20%. Performance of birds on the diets containing 40 % BR and graded with 5 and 10% SCB were significantly (P < 0.05) higher than those on the two control diets (except for feed efficiency). Gross margins for birds on the two test diets were higher by 39 shillings per bird than those on the control diets. Substitution of maize with the rice-milling by-products up to 65 % was observed to be technically feasible and profitable.
Expression of trypanotolerance in N’Dama x Boran crosses under field challenge in relation to N’Dama genome content
(BMC, 2011) Orenge, Caleb; Munga, Leonard; Kimwele, Charles; Kemp, Steve; Korol, Abraham; Gibson, John; Hanotte, Olivier; Soller, Morris
Background: Animal trypanosomosis in sub-Saharan Africa is a major obstacle to livestock based agriculture. Control relies on drugs with increasing incidence of multiple-drug resistance. A previous mapping experiment in an F2 population derived from the indigenous trypanotolerant N ’ Dama cattle crossed to susceptible (Kenya)-Boran cattle under controlled challenge, uncovered a number of trypanotolerance QTL (T-QTL). The present study was to determine expression of N ’ Dama trypanotolerance in a backcross to the Boran under conditions of field challenge, and whether chromosomal regions associated with trypanotolerance in the F2 experiment showed similar effects in the BC population. Methods: 192 backcross animals to the Boran were produced in six batches from June 2001 to December 2006. At one year of age animals were moved to the field and exposed to natural challenge over about one year in Southwest Kenya (Narok). The animals were individually recorded weekly for body weight, packed cell volume, parasitaemia score, and drug treatments, and were genotyped using 35 microsatellite markers spanning 5 chromosomes found in the F2 study to harbour T-QTL. Results: The F1 were most trypanotolerant, Boran least, and BC intermediate. Females showed distinctly higher trypanotolerance than males. There was a positive correlation in the BC population between trypanotolerance and number of N ’ Dama origin marker alleles. QTL mapping revealed T-QTL distributed among all five targeted chromosomes, corresponding in part to the results obtained in the F 2 experiment. Conclusions: N ’ Dama origin trypanotolerance is expressed in a BC population under field conditions in proportion to N ’ Dama origin marker alleles. Consequently, marker assisted selection in such populations may be a means of increasing trypanotolerance, while retaining the desirable productive qualities of the recurrent parent.
Comparing Initial Performance of Macropropagated, Tissue Cultured and Naturally Regenerated Banana Seedlings
(Elewa.org, 2011) Kasyoka, M.R.
Objective: Banana is an important crop for food security and income generation in Kenya. It is also used as fodder especially during the dry season when feed resources are less available. Production of the crop faces many challenges, among them poor seedlings supply systems. Tissue culture was introduced in Kenya about ten years ago but its adoption is still low, largely due to high cost of seedlings as a result of high production cost. There are also few private sector players in the tissue culture sector. As a result farmers have continued to rely on natural regeneration methods to obtain planting suckers. This method is slow and in most cases does not yield adequate planting materials. Macropropagation technology was introduced in Kenya in 2008, but has had only limited evaluation in the country. An ongoing study is evaluating this technology, partly to compare the performance of seedlings from different propagation methods. Methodology and results: Ten seedlings of each method were planted and their establishment evaluated in a field at Kenyatta University Kenya. Initial growth parameters are to be monitored over a period of six months. Data is being recorded on the number of leaves, diameter of the stem from a point initially ten centimeters above the ground, and height of the plantlets recorded at two weeks interval. Results showed that tissue culture seedling have high growth rate initially while naturally regenerated suckers have the least growth rate. The growth rate of macropropagated seedlings was not significantly lower compared to tissue cultures, and maintained a consistent trend over time. Applications of findings: The preliminary findings of this study show that macropropagated seedlings respond the same as tissue cultured seedlings during the early stages of establishment after transplanting. The slow establishment of naturally regenerated suckers was to an extent due to absence of leaves that had been pruned when transplanting.

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