CW-Department of Agricultural Sciences and Technology

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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.
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
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.
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.
Potential challenges facing macropropagation technique in banana
(Bio Sciences, 2011) Njau, N.; Mwangi, M.; Kahuthia-Gathu, R.; Mbaka, J.; Muasya, R.
Objective: Bananas (Musa spp) are an important crop for food security, income for small holders and fodder among other uses. Banana production is greatly constrained by lack of affordable clean planting material. Macropropagation technique has been proposed as a more cost effective method for producing healthy seedlings. This paper reports on some factors that could pose challenges to adoption of this technology in Kenya. Methodology and results: As part of a wider study to evaluate the feasibility of introducing macropropagation to banana growers in central and Eastern Kenya, observations were made on farmer perceptions and other factors encountered during implementation. Farmers appreciate that macropropagation is an inexpensive technology that can produce large quantities of good quality seedlings. However, one factor that could limit its adoption in the target areas is unavailability of corms for propagation. It was noted that farmers are not willing to remove the maiden corms for macropropagation because they perceive this as a loss of the bunch that would have been harvested. Currently many farmers in the target region are notin dire need of planting materials as the plantations that have been managed well are in a good state with little need for replanting. Limited availability of land also implies demand for seedlings to expand plantations is low. The labor required for the macr opropagation procedure is an additional challenge in some areas.Some tasks such as soil and sawdust sterilization, chamber construction and maintenance, corm handling, among others, require considerable amounts of labor. In some areas competition of the available labor with other higher wage activities is a hindrance to successful uptake of this technology. For example men prefer to participate in loading trucks with banana bunches or operating motorcycle taxis, rather than the relatively les paying menial tasks in nurseries. Although macropropagation is a low skill technology, improper removal and manipulation leads to rotting of the corms after placement in the propagation medium. Weevil infestation of corms in some areas is also an additional constraint as infested corms have to be discarded, even though the cost of obtaining them has been incurred. One of the low cost aspects of the macropropagation technology is due to the fact that the nurseries are constructed using locally available materials. However, these materials are prone to rapid damage by termites and the roof can easily collapse during heavy rains or strong winds. Extra measures are therefore required to treat or protect the wood from destruction by termites and to better secure the polythene sheet roofs so as to minimize the need for regular repairs. Application of findings: These challenges need to be looked into and feasible solutions provided. For example, corms that are not heavily infested with weevils can be cured for severaldays after the sheaths have been removed to ensure the eggs, larvae and adult forms have been killed. They can also be treated with chemicals that control weevils. The materials used to build the chambers can be treated with preservatives. To avoid disillusionment, the technology should be better explained to stakeholders so that they appreciate its benefits vis-a-vis other propagation methods, even though it has its limitations. Key words: Banana, Macropropagation, challenges
Effects of Banana Varieties in Central and Eastern Kenya on Macropropagation Technique
(Agroforestry, 2011) Kasyoka, M.R.; Mwangi, M.; Kori, N.; Mbaka, J.; Gitonga, N.
Kenyans obtain most of their food, livelihood, employment and foreign exchange from the agricultural sector. Banana contribution toward this cannot be over looked. Recently banana has become an important cash crop, especially in Central and Eastern Kenya where income from traditional crops especially coffee has drastically reduced. However, banana industry is faced by many challenges among them lack of clean planting materials. Natural .regeneration is inadequate and associated with high risk .of pest and disease spread while tissue culture plantlets are priced above what will be affordable for many small-scale farmers who are the main, stake holders. Macropropagation technology relies on affordable and simple methodology and can be done easily, with adequate training. This. has been used in other countries; Cameroon, and Nigeria' to increase seedling at farm level. The question is whether this technology can be used to propagate local banana genotypes. To answer this, macropropagation chambers were set in different location in Central and Eastern districts namely: Mathioya, Kirinyanga East, Embu East, Meru Central and Imenti South. Fifteen corms of four different varieties (Kampala, Cavendish, Sweet banana and kiganda) were initiated in sawdust media in a chamber which humidity and temperature was increased. Data was collected on earliness of sucker initiation and the number of suckers' (plantlet) of the first 5 corms per variety. In all the six sites, there was a significance variety difference on the number of days from corm planting to sucker initiation; with Kampala variety taking shortest time and had more plantlets per corm while Sweet banana took the longest time and had few plantlets. The response clearly indicated that the 4 varieties can be propagated through this technology to boost seedlings availability, banana production and food security in Kenya.
Varietal Differences of Two Cassava Varieties (Manihot esculenta Crantz) in Response to Low Cost Tissue Culture Technology.
(Elewa.org, 2011) Ogero, K.O.; Mwangi, M.; Gitonga, Nkanata Mburugu; Ombori, O.; Ngugi, M.
Objective: One impediment to adoption of tissue culture technology is the differential response of various crop varieties to the process necessitating development of protocols that target specific varieties or focus on a few varieties that respond better. The varietal differences in response to tissue culture can be attributed to genotypic differences among the various cultivars. In this study the morphogenetic response of nodal explants from two cassava varieties to low cost tissue culture medium was determined with the aim of optimizing a low cost medium that can be used to regenerate a number of cassava varieties. Methodology and results: Nodal cuttings from cassava varieties Muchericheri and KME 1 were initiated on a developed low cost medium in which locally available fertilizers were used as alternative sources for MS macro- and micronutrients. Subsequent growth, elongation and production of leaves, nodes and roots was monitored and compared weekly between the two varieties. There was no significant difference in response to the low cost medium between the two varieties but Muchericheri had a superior performance producing a higher number of leaves, nodes and roots than KME 1
A Low-cost Medium for Sweet Potato Micropropagation
(African Crop Science Society, 2011) Ogero, K.O.; Mwangi, M.; Gitonga, Nkanata Mburugu; Ombori, O.; Ngugi, M.
Tissue culture has not been optimised in sweet potato ( Ipomoea batatas (L) Lam) propagation due to high costs. With an aim of producing affordable disease-free seedlings, a low cost medium was developed and used to regenerate two sweet potato varieties (KEMB 36 and Tainurey). The conventional sources of MS nutrients were substituted with locally available fertilisers. Thirty grammes per litre table sugar was used as a source of carbon. MS medium supplemented with 30g -l table sugar and 3g -l of gelrite was used as the control. The number of leaves, nodes, roots and plant height for the two cultivars were determined and compared . The low cost medium was significantly (P<0.05) cheaper compared to the MS medium costing 94.4% less per litre. KEMB 36 had a regeneration index of 7 nodes per plantlet on the low cost medium, while Tainurey had 3 nodes per plantlet
A Mechanism to Discover Hidden Markets and to Improve Information Flow Towards Food Producers: A Case of Kiambu District, Kenya
(Tropentag, 2012) Nyaga, Elizabeth Kabura; Muriithi, Anthony Gikandi; Gweyi-Onyango, Joseph P.
Food insecurity in many regions in Kenya is mainly attributed to changes in rainfall patterns, lack of markets to sell agricultural produce from regions with surplus and poor infrastructure to distribute to regions facing deficits. Small scale farmers are in desperate need of markets to sell their produce at a good price. They require information on credit and input markets. This paper discusses the methodologies to improve farmers’ access to these markets and enhance access to relevant information that they may find useful in making decisions. The study argues that providing a platform for farmers to interact and transact business directly with buyers, sellers, researchers and other relevant stakeholders in agribusiness would provide market for the farmers. This interaction may facilitate exchange and dissemination of update information on changes in the markets and, changes in consumer needs and taste. Many studies have shown that networking among individual or groups either in social or professional networks may help in development of the members. This paper argues that providing farmers and agricultural extension agents with access to current information and communication technologies (ICT) could be instrumental in finding new markets for the farmers and in dissemination of relevant information. By facilitating the agricultural extension agents to have access to internet, mobile phone and rural radio, hidden markets can be discovered and new information and technology can reach the farmers before they become obsolete. Many businesses have grown through advertising their products online. A national website managed by extension agents can help farmers advertise their produce so that anyone willing to buy can contact the farmer directly. Agricultural based businesses can also advertise their products in the website. Consumers can use the website to buy fresh produce directly from the farmers. Although internet is not available to most households in Kenya, agricultural extension agents can post information of buyers and sellers in village boards and in the market place. This paper discusses how ICT can be implemental in finding new markets and reducing food insecurity in Kenya
Evaluation of Hyk® foliar fertilizer on growth, yield and quality of French Beans (cv. Organdi)
(Kenyatta University, 2014) Ignatius, S.; Mwangi, M.
French beans (Phaseolus vulgaris L.) are a major vegetable export crop in Kenya and a significant income earner to small scale farmers. French beans are grown for processing, including canning and freezing, and demand is steadily increasing. Poor growth vigor is one of the factors that hinder the realization of high yields and pods of high quality. There is therefore need to develop/ identify new products to increase productivity. The objective of this study was to evaluate a newly introduced concentrated inorganic formulation (Hyk®), for its effect on growth vigor, yield and quality of French bean variety Organdi. Hyk® was applied to the plants at different stages of plant growth in Kirinyaga and Murang’a Counties and evaluated against the commonly used foliar fertilizers Nitro spray® and Calmabon®. The study was laid out in complete randomized design and was replicated three times. Data was collected at 50% flowering and included number of flowers, height of the plant, length and width of the leaves. The Hyk® treated plants had a higher growth rate attaining an average height of 39 cm compared to the control’s 37 cm. Hyk® treated plants also had improved yield and quality of the pods, producing over twice the yield of the control treatments. Cost benefit analysis showed that application of Hyk® to French beans yielded a positive net return. The results show that Hyk® foliar fertilizer can be recommended for use in French bean production. Key words: Hyk®, French beans, foliar fertilizer, flowering
Enhancing access to disease-free sweetpotato planting materials through low cost tissue culture for food security and poverty alleviation in Eastern Africa
(ABIC, 2014) Ogero, K.O.; Mwangi, M.; Gitonga, N.M.; Ombori, O.; Ngugi, M.
Sweetpotato is a major food staple in Eastern Africa because of its ease of cultivation and ability to thrive in marginal areas. However, limited supply of disease-free planting materials constrains production. Tissue culture technology offers a solution to this but it is very costly. Hence, it is necessary to have low cost options for production of clean planting materials. In this study, two low cost media were developed and used to regenerate two sweetpotato varieties, KEMB 36 and Tainung. In the first low cost medium (LCM 1), 2g/l of Easygro® vegetative fertilizer (27:10:16 (N: P: K) + microelements) supplemented with table sugar (30g/l) and agar (9g/l) was used as an alternative source for the conventional Murashige and Skoog (MS) basal salts. In the second medium (LCM 2), the conventional sources of four MS macronutrients were substituted individually with locally available fertilizers while Stanes Iodized Microfood® was used as the low cost source of micronutrients. Conventional MS medium (CM) supplemented with 30g/l of table sugar and 3g/l of gelrite was used as the control. The numbers of nodes, roots, leaves and plant height were recorded at 14 days interval for a period of six weeks. A cost reduction of 96.9% in nutrient sources was realized with LCM 1 while LCM 2 led to cost reduction of 94.4%. KEMB 36 had a regeneration index of 7.8 nodes per plantlet on LCM 2 during initiation while Tainung had a mean of 3.8 nodes per plantlet after the sixth week of culture. The two sweet potato varieties recorded regeneration indices of 3.3-7.1 nodes per plantlet during multiplication. This study has shown that it is possible to reduce the cost of sweetpotato tissue culture by adopting alternative nutrient sources
Baseline report on the status of Agricultural training in higher education institutions in Zimbabwe
(Kenyatta University, 2014) Musundire, R.; Mwangi, M.; Mugabe, F.T.; Maboreke, K.M.
Resource constraints in Sub Saharan Africa universities necessitate interventions to strengthen quality of teaching to produce qualified agricultural graduates. The objective of this study was to identify opportunities and ways to improve curricula and teaching capacity for agriculture training in Zimbabwean universities. Data were collected from nine universities from 30 randomly selected students and teaching staff members who responded through self administered questionnaires specific for each category. Most students (90%) studying agriculture were below the age of 25 years. Female students (80%) preferred non-field based specializations such as Food Sciences and Agribusiness. Across all universities 60% of teaching staff had master degrees as highest qualification with 80% being males. Overall, 59% of academics were involved in reviewing curriculum at departmental level. However, 49 % were not adequately capacitated in pedagogy despite the fact that 66 % of respondents acknowledged presence of training programmes at their institutions. In conclusion, effective agricultural training in Zimbabwean universities is limited by gender bias which is in favour of males compared to females leading to preferential selections of disciplines by female students and lack of adequately trained staff members both in their academic disciplines and pedagogy.
1st biennial international conference proceedings on bridging the gap between society, science and industry
(Kenyatta University, 2014-11) Wanjohi, Waceke J.; Kariuki, George; Mwangi, Maina; Gichaga, Cyrus
PREFACE Africa’s greatest hope for development and freedom from poverty is closely linked to the performance of the agriculture sector. Agricultural higher education institutions (HEIs) have critical roles to play in developing well trained manpower to support a thriving agriculture sector that effectively addresses Africa’s needs for food, employment, income and other benefits derived from agricultural activities. However, African HEIs face the common challenges of diminishing resources, diminishing interest in agriculture careers, weak linkages to industry and other stakeholders of the development process, and a constant need to remain relevant and responsive to the needs of society. To extend efforts in addressing the challenges facing agriculture higher education institutions, the School of Agriculture and Enterprise Development (SAED) at Kenyatta University resolved to organise and host a Biennial Conference (every two years). This is an important forum for various stakeholders to share and exchange their knowledge and experiences, and a platform for developing networks between individuals and institutions, through which capacity and expertise can be shared to spur development. This first conference was organised in collaboration with the Alliance for a Green Revolution in Africa (AGRA) and the Horticulture Association of Kenya (HAK), with support from the German Academic Exchange Foundation (DAAD). The conference brought together local and international Scholars, Researchers, representatives of public and private sector, development partners, Non-governmental organisations, and Community based organisations, industry and development practitioners, farmers associations and representatives, among others. The deliberations centred on innovative approaches for strengthening the interaction of academia, researchers and industry to more effectively address the needs of African small scale farmers, consumers and other members of society. Core to the theme of the conference was recognition of a need to develop a generation of agricultural researchers and agroentrepreneurs with the knowledge and skills to tackle the challenges of the 21st Century. This book presents the Proceedings of the 1st SAED Biennial International conference that was held from 30th November to 5th December, 2014 at Kenyatta University, Nairobi, Kenya. It is therefore with great pleasure that we launch the Proceedings of the 1st School of Agriculture and Enterprise Development International Biennial Conference that was held in Kenyatta University, Nairobi, Kenya from 30th November to 5th December, 2014. The five days Conference under the theme “Bridging the gap between the Society, Science and Industry” featured a rich mix of keynote addresses, technical papers and poster presentations, exhibitions, plenary panel discussions and field excursion. The organizing committee members representing Kenyatta University, AGRA, the University of Nairobi, Horticulture Association of Kenya, DAAD, Kenya Agricultural and Livestock Research Organization and other stakeholders worked tirelessly to ensure the success of the conference. The commitment, diversity of ideas and resources contributed by the various stakeholders in the committee significantly increased the quality of deliberations and eased the task of organizing the conference. The opportunity to host celebrated Pan-African and global scholars, the next generation of young researchers, policy makers and opinion shapers, innovators and industry practitioners was a great motivation to deliver a high quality conference. The committee greatly thanks Kenyatta University Management, Conference Organizers, Collaborators, Sponsors, Participants, Government of Kenya and all other stakeholders for their valuable contributions towards the success of the forum. We particularly thank the then Cabinet Secretary for Ministry of Agriculture, Livestock and Fisheries Hon. Felix Koskei for officially opening the conference. We are delighted to have worked together to organize this conference successfully.
Iron Concentrations in Roots and Edible Organs of African Indigenous Vegetable Species
(Tropentag, 2015) Eckhardt, Ulrich; Beer, Julius; Bessler, Holger; Nambafu, Godfrey N.; Onyuka, Enos; Mwonga, Samuel; Andika, Darius O.; Gweyi-Onyango, Joseph P.; Engels, Christof
Iron (Fe) deficiency is among the 10 leading human health risks causing “hidden hunger” in sub- Saharan Africa. Iron concentrations and bioavailability are often higher in leafy vegetables than in staple crops like maize and sorghum. Therefore, increasing food diversity through vegetable production and consumption is an option to mitigate Fe deficiency. The aim was to quantify Fe uptake and distribution between roots, stems and leaves in selected African indigenous vegetable (AIV) species, and to compare species responses to different rates of Fe supply. Plants of five leafy AIV species (African night shade Solanum scabrum, amaranth Amaranthus cruentus, cowpea Vigna unguiculata, spider plant Cleome gynandra, Ethiopian kale Brassica carinata) and a standard species commonly grown in Kenya (kale Brassica oleracea acephala group) were grown in nutrient solution at three rates of Fe supply (sub-optimal to induce Fe deficiency responses, optimal for growth, supra-optimal to test if Fe density in edible organs can be enhanced by additional Fe fertiliser application). Leaf chlorophyll content (SPAD-meter) and pH of the nutrient solution were measured at regular intervals to quantify shoot and root responses to Fe deficiency. At harvest, biomass and mineral nutrient concentrations were measured separately for roots, stems and leaves. The species markedly differed in their early root responses to Fe deficiency. Whereas in amaranth, proton extrusion from roots was significantly increased at low Fe supply compared to medium and high Fe supply, in spider plant and kale proton extrusion was not influenced by Fe supply. Fe concentrations in the plant dry mass strongly varied among plant organs and decreased in the order roots >> leaves > stems. In all organs, Fe concentrations were significantly affected by species. Concentrations in shoots varied from 17 (Ethiopian kale) to 39 mg Fe kg−1 dry mass (amaranth) at low Fe supply, and from 42 (Ethiopian kale) to 127 mg Fe kg−1 dry mass (cowpea) at high supply respectively Responses of Fe density in edible plant organs indicate that the potential for increasing the nutritional value of leafy vegetables by Fe fertilisation (biofortification) is largest in cowpea and spider plant.
Cadmium Uptake and Distribution to Edible Organs in African Indigenous Vegetables
(Tropentag, 2015) Onyuka, Enos; Husen, Wilhelm van; Nambafu, Godfrey N.; Bessler, Holger; Andika, Darius O.; Gweyi-Onyango, Joseph P.; Mwonga, Samuel; Ulrichs, Christian; Engels, Christof
Cadmium (Cd) is toxic to humans. The most important source for dietary intake is consumption of plant products, whereby Cd concentrations in leafy vegetables are particularly high. In periurban areas, soils are often contaminated with Cd. Thus, recommendations to increase vegetable consumption should consider species-specific uptake and allocation to edible plant organs. Cadmium uptake and distribution within plant was compared in various species to derive recommendations for vegetable production on contaminated soils. Four African indigenous vegetable species (African Nightshade Solanum scabrum, amaranth Amaranthus cruentus, cowpea Vigna unguiculata, spider plant Cleome gynandra), and a standard species commonly grown in Asia (Pak Choi Brassica rapa chinensis) were grown in nutrient solution at three Cd-concentrations: 0.1 (low), 1.0 (moderate) and 2.5 μM Cd (high contamination). Biomass and mineral nutrient concentrations were measured in roots, leaves, stems and lateral branches. Growth was little affected by Cd supply with the exception of amaranth and cowpea. In these species, growth of shoot organs was substantially reduced at moderate and high supply. Growth depression was associated with low leaf iron concentrations indicating Cd-induced iron deficiency. In all species Cd concentrations were higher in roots than in shoot organs, which is in accordance with xylem loading being an important barrier for Cd distribution within plants. At moderate and high supply, Cd concentrations in shoot organs strongly differed among species. Concentrations were particularly low in cowpea, and high in amaranth and African Nightshade. Low Cd concentrations in shoot organs of cowpea were associated with low apparent uptake and translocation rates of Cd from roots to shoots. At all rates of Cd supply, Cd density in edible organs was significantly influenced by species. Cadmium density was particularly low in cowpea and Pak Choi. Based on a vegetable dish of 250 g fresh mass, best choice of species reduced Cd intake by 0.1 mg at low supply (amaranth versus African Nightshade), 0.7 mg at moderate (cowpea versus African Nightshade) and 1.7 mg at high Cd supply (cowpea versus
Effects of companion crops on population dynamics of maize lethal necrosis disease vectors in Bomet County, Kenya
(2015-06) Namikoye, E. S.; Kariuki, G.; Kinyua, Z. M.; Githendu, M. W.; Kasina, M.
Maize is the most consumed staple food crop in Kenya with a per capita of 110kg. It is equally an important commercial crop particularly in high potential areas. Currently, the presence of Maize lethal necrosis disease (MLND) has constrained its production. The disease is challenging to manage because it is a co-infection of maize by two viruses, the Maize chlorotic mottle virus and Sugarcane mosaic virus, which are vectored mainly by C0111 thrips iFrankliniella Williamsi) and C0111 leaf aphids (Rhopalosiphum maidis), respectively. This study was carried out to assess the potential for companion crops to act as traps or repellents for these vectors, thus contributing to vector management. Trials were carried out in fanners' fields in Bomet County. Treatments included Napier, coriander, millet, sorghum and maize, arranged in a randomized complete block design with four replicates for two seasons, November 2014- April 2015 and April-August 2015. Each crop was planted either as an intercrop or a border crop with maize as the main crop. We present results from the first season. There were significant differences (P
Communicating and publishing research: Developing and strengthening journals
(INASP, 2016) Maina, Mwangi
Influence of Priming, Dressing and Agroecologies on Storage of Selected Soyabean Genotypes
(Egerton University, 2016) Chirchir, J.G.; Mwangi, M.; Nyamongo, D.; Gweyi-Onyango, P.J.

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