Horticulture

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Effect of intercrops on thrips species composition and population abundance on French beans in Kenya
(2011-12-12) Nyasani, J.O; Meyhöfer. R.; Subramanian, S.; Poehling, H.-M.
The study aimed at determining thrips species composition and thrips population density on French bean planted as a sole crop and as an intercrop with either sunflower, Irish potato, or baby corn, in various combinations. Field experiments were conducted in two seasons to examine: (1) thrips population development and thrips species composition over time, (2) effect of intercrops on thrips population density and natural enemies, and (3) effect of intercrops on French bean yield. The experiments were conducted at the Kenya Agricultural Research Institute, Embu, Kenya in a randomized complete block design with four replicates. The thrips population on French beans increased with time. It showed a peak at the flowering stage then started declining when the crops were nearing senescence. French beans hosted four thrips species, Megalurothrips sjostedti (Trybom), Frankliniella schultzei (Trybom), Frankliniella occidentalis (Pergande), and Hydatothrips aldolfifriderici (Karny) (all Thysanoptera: Thripidae) in order of decreasing abundance. The main thrips species on Irish potato and sunflower was F. schultzei. Baby corn hosted only Frankliniella williamsi (Hood) and Thrips pusillus (Bagnall). A monocrop of French bean hosted more thrips than a French bean intercrop mix. Thrips natural enemies such as Orius spp. and Ceranisus spp. were recorded in all crop plants but in especially high numbers on French bean and baby corn, respectively. Plots with French bean alone had about 1.4 times higher yields compared to intercropped plots of French bean with sunflower and French bean with baby corn. However, the percentage of pods that could get rejected on the market due to thrips damage was highest on plots with French bean alone (68 and 63%) and lowest on plots with French bean and baby corn (35 and 37%) in the first and second seasons, respectively. This study showed that a complex of thrips is found in the field and its composition varies with crop stage and species. Intercropping French bean with other crops compromises on French bean yield but reduces damage to the French bean pods, thereby enhancing marketable yield.
Genetic diversity in Napier grass (Pennisetum purpureum) cultivars: implications for breeding and conservation
(Journal for Plant Science, 2013-10-30) Bramwel W. Wanjala; Meshack Obonyo; Francis N. Wachira; Alice Muchugi; Margaret Mulaa; Jagger Harvey; Robert A. Skilton; Janice Proud; Jean Hanson
Napier grass is an important forage crop for dairy production in the tropics; as such, its existing genetic diversity needs to be assessed for conservation. The current study assessed the genetic variation of Napier grass col lections from selected regions in Eastern Africa and the International Livestock Research Institute Forage Germplasm Ethiopia. The diversity of 281 cultivars was investigated using five selective amplified fragment length polymorphism (AFLP) markers and classical population genetic parameters analysed using various software. The number of bands generated was 216 with fragments per primer set ranging from 50 to 115. Mean percentage polymorphic loci was 63.40. Genetic diversity coefficients based on Nei’s genetic diversity ranged from 0.0783 to 0.2142 and Shannon’s in formation index ranged from 0.1293 to 0.3445. The Fst value obtained was moderately significant (Fst ¼ 0.1688). Neighbour-joining analysis gave two distinct clusters which did not reflect geographical locations. Analysis of molecu lar variance showed all variance components to be highly significant (P , 0.001), indicating more variation within (91 %) than between populations (9 %). Results suggested moderate genetic differentiation among Napier grass popu lations sampled, which could imply a high germplasm exchange within the region. The AFLP markers used in this study efficiently discriminate among cultivars and could be useful in identification and germplasm conservation.
Effects of deficit irrigation on yield and quality of Onion crop
(University of Eldoret, 2014) Rop, David Kiplangat
There is shortage of onions in Uasin Gishu and Nandi counties during dry season from October to March when the demand is high. Rainfall during the period is inadequate for crop development. This study aimed at testing Deficit Irrigation technology as an appropriate irrigation management strategy that could improve crop water productivity and give optimum Onion crop yield. A field trial was conducted in Nandi County with drip irrigation system and six irrigation treatments replicated three times in a randomized complete block design. Full supply of crop water requirement to meet 100% ETc (T100) acted as a control. The crop was subjected to five stress levels T90, T80, T70, T60 and T50 at vegetative and late season growth stages. Establishment and yield formation stages were given adequate water to meet normal crop water demand (ETc). The treatments were protected from receiving extra water from the rain. The yield, biomass, quality and irrigation water use efficiency were determined. The data collected were statistically analyzed using ANOVA. The variation in yield ranged from 34.4 ton/ha to 18.9 ton/ha and that of quality from 64 mm to 35 mm diameter for T100 and T50 respectively. The treatments T90, T80, T70, and T60 gave yields of 33 ton/ha, 32 ton/ha, 25 ton/ha and 23 ton/ha with corresponding bulb diameter of 60 mm, 58 mm, 53 mm and 40 mm. Water stress of 20% led to optimum yield with water saving of 10.7%. The results obtained from the field trial were used to calibrate and validate the performance of AquaCrop Model using separate data sets. Statistical indices, Model efficiency (E), root mean squared error (RMSE), coefficient of residuals (CRM) and coefficient of determination (R2 ) were used to evaluate the performance of AquaCrop model in simulating yield, biomass, canopy cover and soil moisture parameters. The model performance statistical index was found for R2 as 0.912 for canopy and 0.798 for soil moisture in confirming model calibration. Similarly, the index (R2 ) for confirming model validation for canopy and soil moisture was 0.892 and 0.616 respectively. The model was applied to derive full (T100) and deficit (T80) irrigation schedules for three weather regimes from October-March growing seasons between 2003 and 2012 giving rise to 34 and 30, 38 and 34, 45 and 40 irrigation events each of 13 mm respectively. It was concluded from the results that deficit irrigation (DI) at vegetative and late growth stages significantly influenced yields. DI influenced the size and size distribution of fresh Onion bulbs significantly (Fcalculated = 96.28, Fcritical = 3.12). However, it did not significantly affect the shape of onion. AquaCrop model performance in simulating yield, green canopy cover and soil moisture declined at higher stress levels. The model is useful in developing irrigation schedules for different weather regimes that can be applied by farmers through extension services. It was recommended that the model be used to simulate yield at lower stress levels and adopted for irrigation scheduling by farmers and field extension staff. DI technology should be adopted for optimum yield and maximum water productivity.
Modelling Relationship between Soil Permeability and Organic Carbon in Pesticide Transport into Groundwater
(2015-09-29) Simon Mburu Njoroge; Odipo Osano; Thomas Mutuku Munyao
Groundwater contamination by pesticides is an environmental health concern throughout the world. Many pesticides do not leach because they are adsorbed on the soil particles or organic matter even though they may have a relatively high solubility. The objective of this study was to determine the relationship between soil permeability and organic carbon in the transport of pesticides into groundwater along the shore of Lake Naivasha, using regression analysis of soil permeability and organic carbon data collected along the shore. The results showed that the soil organic carbon (foc) positively affected the soil permeability (k) and were related by the equation k= 80.724(1.726)foc . It was concluded that organic carbon increased soil permeability by 30%, thereby recharging the aquifer while at the same time reducing pesticide transport into groundwater. Based on these findings the study recommended that the use of compost (organic amendments) should be increased in place of inorganic fertilizers.
Rose rootstocks position and auxins affect grafting take of ‘Inca’
(2016) Otiende, Millicent Adhiambo; Nyabund, Julius Omondi; Ngamau, Kamau
Inadequate grafting take of some of the rose cultivars may cause economic losses. The study was conducted to determine the effects of cutting position (top, middle and bottom) of Rosa hybrida rootstocks (‘Natal Briar’ and ‘Rosa Progress’) and auxins (0 %, 0.4 % IBA and 0.2 % NAA) on rooting and grafting take of rose cultivar ‘Inca’. Changes in endogenous carbohydrate content during rooting were measured on days 0, 3 and 7 after sticking. The experiment was factorial in a completely randomized design. Interaction between cutting position and rootstock was significant (P ≤ 0.05) for most of the parameters measured. The shoot height, root number, percent rooting and grafting take increased towards the basal position in ‘Rosa Progress’. In ‘Natal Briar’, the shoot and root growth parameters increased towards the top though non significant except grafting take that significantly increased towards the basal position. The auxin treated cuttings recorded significantly (P ≤ 0.05) higher grafting take and rooting percentage than the control. 0.4 % IBA exhibited higher shoot height, leaf number and root number than 0.2 % NAA. The rootstock ‘Natal Briar’ recorded significantly (P ≤ 0.05) higher rooting percentage and grafting take than ‘Rosa Progress’. Middle and top position cuttings of ‘Rosa Progress’ and ‘Natal Briar’ recorded higher carbohydrate content, respectively than bottom position cuttings. Bottom position recorded higher sucrose content on day 3 than days 0 and 7 after planting in ‘Rosa Progress’. ‘Natal Briar’ exhibited significantly (P ≤ 0.05) higher carbohydrate content than ‘Rosa Progress’. The increase in growth with top position cuttings of ‘Natal Briar’ could be attributed to high carbohydrate content. The high growth responses in bottom position cuttings of ‘Rosa Progress’ could be attributed to high sucrose content on day 3 after planting. The stem cuttings of rootstocks for top grafting rose cultivar ‘Inca’ should be taken from bottom position cuttings of both rootstocks, and auxins should be applied to increase rooting and grafting take.
Farmer-Led Seed Enterprise Initiatives to Access Certified Seed for Traditional African Vegetables and its Effect on Incomes in Tanzania
(International Food and Agribusiness Management Review, 2016-02-01) Srinivasulu Rajendrana; Victor Afari-Sefa; Daniel Kimani Karanja; Richard Musebe; Dannie Romneye; Magesa A. Makaranga; Silvest Samalig; Radegunda Francis Kessyh
Farmers need access to certified seed stocks for efficient production of traditional African vegetable seed. However, access to quality certified seed is constrained by several factors. Primary data from four selected regions of Tanzania was analyzed to examine the causal linkages among traditional African vegetable farmers’ decisions to participate in farmer-led seed enterprises and their access to quality certified seeds. The effect of farmers’ access to certified traditional African vegetable seed on revenue generated from their seed sales in the study locale was assessed. This study concludes that farmers’ revenue from traditional vegetable seed sales is positively and significantly influenced by access to certified seed. Indeed, access to certified seed can be increased, if farmers participate in farmer-led seed enterprises, and if they have more frequent contact with village extensionists. Relevant policy actions and recommendations for improving farmer-led seed enterprises are offered
Screening Napier grass accessions for resistance to Napier grass stunt disease using the loop-mediated isothermal amplification of DNA (LAMP)
(2016-09-01) N.I.E. Wamalwa; C.A.O. Midega; S. Ajanga; N.E. Omukunda; F.N. Muyekho; G.O. Asudi; M. Mulaa; Z.R. Khan
Napier grass stunt (NGS) disease is a major threat to Napier grass cultivation and the smallholder dairy industry in East and Central Africa. The disease is caused by a phytoplasma, which is transmitted by the leafhopper Maiestas banda (Kramer) (Hemiptera: Cicadellidae). The current study was conducted to identify among 65 Napier grass accessions that could be resistant to NGS disease using the loop mediated isothermal amplification of DNA (LAMP). The accessions were caged with NGS phytoplasma infected Napier grass as inoculum source and M. banda as the vector. All Napier grass accessions were subjected to phytoplasma testing thereafter 18 phytoplasma negative and five asymptomatic accessions were selected and used in further screening by subjecting the extracted DNA to LAMP. Plant response to the NGS phytoplasma by symptom expression, impact on yield-related parameters and phytoplasma infection was used to evaluate tolerance or resistance over a period of three months. Most Napier grass accessions were susceptible to the disease except plants belonging to accession 16789 which were negative by LAMP. Napier grass accession 16807 was found to be tolerant with 60% plants positive by LAMP and 90% plants symptomless. Accessions 16822 and 16817 had moderate tolerance with one and two plants positive by LAMP, respectively. Accession 16812 was slightly tolerant with 58.3% plants positive by LAMP and 33.3% of the plants showing symptom remission in the second re-growth. This study indicates there could be resistance and tolerance to NGS disease which could be exploited in the development of an integrated management strategy for this disease
Evaluation of Common Bean Production Systems and Fertilizer Use in Nandi South
(University of Nairobi, 2017) Okumu Oliver; Muthomi J.; Narla R.; Nderitu J.; Lauren J.; Ojiem J.
High fertilizer cost and increased concern for ecological sustainability have led to improved interest on green manure and organic fertilizer. The study evaluated common bean production systems and organic fertilizer use by farmers in Nandi South. A semi structured questionnaire was administered to individual farmers in the form of interviews and the data was analyzed through descriptive statistics, frequency counts and percentages. Results showed that majority of the farmers were women with a mean age of 51.6 years. Many farmers 59% cultivated improved bean varieties sourced from their own farms and applied fertilizers albeit different quantities. The results further indicated that 67% of farmers in Koibem and 57% in Kapkerer applied green manure as a soil amendment. Addition of green manure to soils helps in improving soil conditions and increasing crop yields in low soil fertility areas. Green manure use as soil amendments is an ecologically sustainable way of increasing yield. Relevance to innovation. Many modern agricultural practices have unintended negative consequences and therefore there is growing concern about sustainable and better agricultural systems. It is therefore time to assess the importance and future role that soil improving legumes may play in agricultural system. Application of lablab legume species as green manure is an important practice for sustainable agriculture production as the crops fix nitrogen and has deep and extensive root system that allows for nutrients extraction and recycling. Green manure has favou..rable N to P ratios and has predictable N activity hence its application will increase yield.
Mainstreaming Efficient Legume Seed Systems in Eastern Africa: Challenges, opportunities and contributions towards improved livelihoods
(Food and Agriculture Organization of the United Nations, 2018) Ojiewo, Christopher Ochieng; Rubyogo, Jean-Claude; Wesonga, John; Bishaw, Zewdie; Abang, Mathew M.; Gelalcha, Solomon
Legumes are important components of sustainable farming systems. They are useful to diversify and intensify cropping systems as double, catch, relay and intercrops; fix ‘free’ nitrogen to soils from the atmosphere and improve soil health that boost cereal crop yields; act as rotation crops for breaking disease and pest cycles; increase and diversify smallholder incomes (and hence buffer them from the effects of price, pest and climate-related production fluctuations); enhance quality of household diets because of their higher protein and micro-nutrient content compared with starch-based staple cereal crops; and provide good sources of animal feed (high protein crop residues and byproducts) and low carbon footprint, mitigating climate change...
Farmers’ perceptions and coping strategies with sweet potato weevil and characterization of sweet potato genotypes for diversity and resistance to cylas puncticollis boheman in kenya
(Jomo Kenyatta University Of Agriculture And Technology, 2018) Lilian Anyango Ochieng
Optimizing yield and economic returns of rain-fed potato (Solanum tuberosum L.) through water conservation under potato-legume intercropping systems
(Elsevier, 2018-09-30) Gitari, Harun I.; Gachene, Charles K. K.; Karanja, Nancy N.; Kamau, Solomon; Nyawade, Shadrack; Sharma, Kalpana; Schulte-Geldermann, Elmar
Even though potato (Solanum tuberosum L.)-based intercropping systems are widely practised in developing countries, only a few studies have focused on legumes as the companion intercrops. This study was conducted to assess the effect of incorporating legumes into the potato production system on ground cover, soil moisture content (SMC), tuber and legume yield, potato equivalent yield (PEY), gross and net income and benefit: cost ratio (BCR). The treatments comprised of pure potato stand (PS), potato-dolichos (Lablab purpureus L.) (PD), potato-garden pea (Pisum sativum L.) (PG) and potato-bean (Phaseolus vulgaris L.) (PB). Results indicated a significantly higher (69%) ground cover at tuber initiation stage in PD compared to 66% in PG and PB and 56% in PS. Similarly, the highest SMC values were recorded at tuber initiation stage: 230, 207, 201 and 188 mm m−1 in PD, PG, PB and PS, respectively. Fresh tuber yield was highest in PS (36 t ha−1) and PD (35 t ha−1) and lowest in PG (29 t ha−1). PEY was higher under intercropping than monocropping systems. Potato-dolichos was the most profitable intercropping system with a net income of US$ 9174 ha−1 and a BCR of 5.7 compared to PS (US$ 7436 ha−1) with a BCR of 5.1. The study showed that dolichos is a promising legume crop that could be integrated into potato cropping systems to improve CWP without compromising the tuber yield.
Mapping of Quantitative Trait Loci (QTL) Related to Drought Tolerance in Common Bean (Phaseolus vulgaris L.) Using F2 Population from (KATB1 Χ GLP2)
(International Annals of Science, 2018-10-13) Charles Langat; Omwoyo-Ombori; Richard Cheruiyot; Moses Gathaara; David Karanja; Philip Leley
Many of the common bean growing regions around the world are prone to drought stress, making drought the major challenge to production and yield stability in rainfed environments. Mapping of yield-associated loci under drought stress will offer a better understanding of the genetics of drought tolerance to the plant breeders and therefore, will accelerate the selection of drought tolerant crop varieties through marker assisted selection (MAS).The current study reports identification of quantitative trait loci (QTL) linked to physiological, phenological, yield and yield related traits using 120 F2 population derived from a cross between two common bean genotypes, KAT B1 (drought tolerant) and GLP2 (drought susceptible) evaluated under drought stress and well-watered conditions. The research was conducted at the Agricultural and Mechanization Institute, Machakos, Kenya. The F2 population showed significant variation in traits under drought stress. From the 374 polymorphic SNP markers surveyed, 20 genomic regions were identified for various traits under drought stress, individually explaining 2.6 to 21.3% of phenotypic variation. The number of QTLs identified per trait were: 2-grain/seed yield (GY); 1-number of branches (NBP); 2-stem biomass (SB); 1-leaf biomass (LB); 1-pod biomass (PB); 3-days to flowering; 2-days to maturity (DM); 4- number of pods per plant (NPP); 1-seed weight (SW); 2-stomatal conductance (SMTL) and 1-leaf water potential (LWP). QTLs for number of pods per plant, number of grains/seeds per pod, days to flowering, leaf biomass and stem biomass were found co-locating with QTLs for grain yield on chromosome Pv02 under drought stress treatment. The cumulative effects of these QTLs on chromosomes 2 resulted in higher grain/seed yield. This study has provided information on QTLs in common bean that could be used in selection purpose for grain yield under drought conditions.
Farmer perceptions of legumes and their functions in smallholder farming systems in east Africa
(Taylor & Francis, 2019-05-04) Muoni, Tarirai; Barnes, Andrew P; Öborn, Ingrid; Watson, Christine A; Bergkvist, Göran; Shiluli, Maurice; Duncan, Alan J
Legumes play an important role in sub-Saharan Africa (SSA) farming systems through the provision of food, feed, fuel, income and a range of biophysical benefits, such as soil fertility enhancement and erosion control. However, their full potential is not being realized. The purpose of this study was to assess farmers’ perceptions and knowledge towards legumes and the rationale of farmers for current legume production practices using a survey of 268 farmers in the Democratic Republic of Congo and Kenya. Most of the farmers had some knowledge of legumes and their characteristics. However, they had little knowledge of some key functions, including soil erosion control and soil fertility improvement. Most farmers relied on radio and other farmers for legume-related information. Farmers with relatively large livestock holdings ranked provision of livestock feed as an important legume function. We conclude that farmers put more value on short-term benefits of legumes including food and income than long-term benefits such as natural resource management and thus grain legumes are more readily identified by farmers than forage species. Also, we conclude that farmers require more than just information about legumes to increase uptake, they also require improved market access to procure inputs and sell products to realize other benefits that are associated with growing legumes.
Endogenous Carbohydrate Content of the Cutting Positions at Time of Severance and IBA Concentration Influence Rooting of Rosa hybrida Rootstocks
(2019-05-12) Otiende, Millicent Adhiambo; Maimba, Francis Munyiri
Insufficient rooting of cuttings may result in economic losses and limit the use of some rootstocks. Present study was aimed at evaluating the effect of cutting position (top, middle and bottom) and Indole-3-butyric acid (IBA) concentrations (0%, 0.2%, 0.4% and 0.6%) on rooting of Rosa Progress and Natal Briar cuttings. Carbohydrate content of the cutting positions at the time of severance was determined. The experiment was factorial in a completely randomized design (CRD). The root and shoot growth parameters as well as carbohydrate levels in the leaves increased acropetally in both rootstocks. Indole-3-butyric acid (IBA) treatment enhanced root number, total root length and root fresh weight of both rootstocks. Among the IBA treated cuttings 0.4% had higher rooting and survival percentage than 0.2% in Natal Briar. Rosa Progress exhibited higher root number, shooting and survival percentage than Natal Briar though carbohydrate content in the original leaf at the time of severance was low. Carbohydrate content in the leaf of both rootstocks was higher than in the stem and this presumably ensured continuous supply of carbohydrates to the stem base during the rooting process. Auxin (IBA) treatment and high endogenous carbohydrate in the original leaf at the time of cutting severance enhanced rooting especially in Natal Briar
Climate-resilient horticulture for sustainable county development in Kenya
(Wageningen University and Research, 2020-04) Patrick, Esther M.; Koge, Jessica; Zwarts, Emiel; Wesonga, John M.; Atela, Joanes O.; Tonui, Charles; Kilelu, Catherine; Goosen, Hasse; Coninx, Ingrid; Koomen, Irene
mmary Climate change presents one of the greatest challenges to the productivity and sustainable growth of the agricultural sector in Kenya due to extreme events such as droughts and floods as well as changes in temperature. Horticultural crops are particularly sensitive to climate change because of their high water demand and strict temperature requirements. Increased or decreased rainfall and increased temperature result in drought or flooding, lack of water for irrigation, and pests and diseases epidemic can affect the suitability of areas for growing horticultural crops. Understanding the impacts of climate for a given crop under specific conditions is key to supporting further development of the horticulture sector. While horticulture is a priority economic subsector in many counties, it is not known how the counties position themselves with regard to dealing with climate change threats in the sector. A review of the literature shows how climate change significantly affects the performance of horticultural crops across a variety of climatic zones and that counties need to be better prepared to address these effects. Horticulture covers myriad crops (including fruits and vegetables), which are affected by climate change in different ways. Seasonal patterns, both for temperature as well as (onset of) rainfall are changing. Temperature thresholds for specific crops are being exceeded, while some areas are now more favourable for growing certain crops where previously temperatures were too low. Suboptimal temperatures affect both the yield and quality of produce. The horticulture sector has also experienced incidences of pests, such as Tuta absoluta on tomato; climate change is a confounding factor to the spread and establishment of these pests. Agriculture which is highly affected by climate change is devolved to counties; as such, policies relevant to it are expected to be implemented at county level. An analysis of the County Integrated Development Plans showed that horticulture is a high-value subsector that plays a major role in generating revenue for county development. Most counties have prioritized horticulture and made substantial investments. Climate change is acknowledged as a threat to different sectors, but there is only scant analysis of the factors causing it, effects it will have and proposed responses to it. Farmers and crop officers from Kiambu and Kajiado counties are aware of climate change and its effects on horticulture. However, understanding of the relationship between cause and effect and of possible mitigating actions is weak. We observed that at all levels, in the field as well as at county level, preparedness for climate change is low and government support to the farmers is also limited. Due attention and informed decision-making based on, for example the Kenya Climate Atlas that is currently being developed, is required.
Revisiting intercropping indices with respect to potato-legume intercropping systems
(Elsevier, 2020-11-01) Gitari, Harun I.; Nyawade, Shadrack O.; Kamau, Solomon; Karanja, Nancy N.; Gachene, Charles K. K.; Raza, Muhammad A.; Maitra, Sagar; Schulte-Geldermann, Elmar
Intercropping is gaining popularity in developing countries as a viable strategy for diversifying cropping systems to ease food insecurity, given that arable land is shrinking, and demand for food crops is increasing due to rapid population growth. A field experiment was conducted in 2015 and 2016, to examine the biological and economic viability of two intercropping systems (potato-dolichos and potato-bean planted in two potatoes to legume population density ratios: 1.1:2 and 1: 2.4) and their corresponding pure stands. Intercropping systems were also evaluated based on five competition indices: relative crowding coefficient (K), aggressivity (A), competitive ratio (CR), intercropping advantage (IA) and actual yield loss (AYL). Although biological feasibility revealed that intercropping decreased the yield of intercrops compared with respective monocultures; the economic assessment of different cropping systems indicated that intercropping resulted in a higher remuneration (gross and net income) than pure stands. Intercropping potato with a high population of legume (in 1: 2.4 patterns), resulted in not only higher system productivity but also potato equivalent yield compared to 1.1:2. Intercropping proved to be advantageous with AYL decreasing with increasing proportion of the legumes, whereas IA increased as the population of legumes increased. With regard to competition between the intercrops, the potato was more aggressive (A of potato was positive, and its CR > 1) in all cropping systems, and it dominated over legume (that had negative A values and CR < 1). Aggressivity and dominance capacity was higher in 1: 2.4 than 1.1:2 series. These results suggest that potato-legume intercropping may provide viable intensification options, especially for smallholder farmers.
Managed bees as pollinators and vectors of bio control agent against grey mold disease in strawberry plantations
(Academic Journals, 2020-12-31) Macharia, Jane Muthoni; Gikungu, Mary Wanjiku; Karanja, Rebecca; Okoth, Sheila
Pollination by bees and other animals significantly increase both crop yields and quality. Bees also support the transfer of bio-control agents for suppression of crop pests and diseases through bio-vectoring technology that has not been applied in Africa. Two farms were set up to test the ability of managed bees to disseminate Trichoderma harzianum to control Botrytis cinerea, on strawberries. At on-station farm, three treatments (bee-vectoring inoculum, spraying and control) with 4 replicates each were set up; while on-farm, normal farmer practices were employed. A nuclear beehive fitted with a two-way dispenser was loaded with two grams of T. harzianum inoculum. Fifteen bees and flowers from each treatment were picked and cultured in the laboratory. Fruits and flowers infected with B. cinerea were recorded, while healthy fruits were counted, weighed and equatorial and polar diameter determined. Each bee carried 22.4±4.9×102 colony -forming units of T. harzianum. Flowers from the sprayed treatment had significantly higher Colony-Forming Unit’s F (3,140), (PË‚0.05) than the bee-vectored treatment. Grey mold disease levels on fruits were significantly lower (PËƒ0.05) in sprayed, bee- vectored and control treatment than in farmer’s practice treatment. Fruits from spray treatment weighed significantly higher than those from control treatment F (3,2122), (PË‚ 0.05). The number of seeds, equatorial and polar diameter per berry were significantly higher (F=3, 2122, PË‚0.05) in farmer’s practice treatment. Managed bees proved effective in vectoring T. harzianum but, sufficient Colony-Forming units had to be delivered for effective control of the disease. Key words: Trichoderma harzianum, grey mold, strawberry, biocontrol agent, managed bees, bio-vectoring technology.
Quality of Lablab (Lablab purpureus) Forage Preserved as Hay or Silage
(Indian Journal of Animal Nutrition, 2021) Wangila Anthony Juma; Gachuiri Charles Karuku; Muthomi James Wanjohi; Ojiem John Okeyo
Shortage of livestock feeds during the dry season is a major constraint to livestock production in Kenya. This scenario is due to dependence on rain fed forage production resulting in shortages during the dry season and excess during the wet season. This situation can be ameliorated through conservation, but losses occur when forages are conserved. The main objective of this study was to assess the effects of on-farm conservation methods on quality of lablab fodder. Fodder from eight varieties of lablab;DL1002, Ngwara Nyeupe, Echo-Cream, Black Rongai, Eldo-Kt-Cream, Eldo-Kt-Black1, Brown Rongai and Eldo-Kt-Black2 were conserved on-farm either as hay or silage. The conserved and fresh fodder were analyzed for dry matter content, crude protein, ash content, neutral detergent fibre (NDF), acid detergent fibre (ADF), acid detergent lignin (ADL) and in vitro dry matter digestibility (IVDMD). Lablab silage was analyzed for pH and total ammonia nitrogen. Crude protein content declined significantly; by 4.2 g/100 g when fodder was conserved as hay and by 6.0 g/100 g in silage. The NDF content increased significantly by 7.6 g/100g in lablab hay but declined by 4.2 g/100 g in silage while ADF increased by 6.1 g/100 g in hay and declined by 5.0 g/100 g in silage. A significant decline of 3.2 g/100 g of lignin was observed in silage with no difference in the hay. The IVDMD declined significantly by2.8 g/100 g in lablab hay and increased by 4.5 g/100 g in silage. The pH of lablab silage ranged from 4.37 to 4.89 while total ammonia nitrogen ranged from 27 to 41 g/100 g for different lablab varieties. Conservation of lablab as silage was found to be a superior on-farm method compared to hay making.
Single Stem Rouging of Banana Xanthomonas Wilt Infected Plants for Orchard Rehabilitation
(Asian Journal of Agricultural and Horticultural Research, 2021) Kwach, Johnson Kisera; Nyakomitta, Peter Sungu; Muthomi, James Wanjohi; Ndayitegeye, Olivier; Okoko, Evelyn Nasambu
Banana Xanthomonas Wilt (BXW), caused by Xanthomonas campestris pv. musacearum (Xcm), a devastating disease, causes up to 100% loss and affects all banana varieties. The disease is widespread in East and Central Africa region. Study objective was to evaluate the performance of single stem rouging options for rehabilitation of severely affected banana orchard. Five single stem rouging options were implemented in banana orchard with 80% BXW severity in Western Kenya. The options included rouging of infected banana plants; uprooting, cutting at the base, injecting 20 ml of glyphosate herbicide at the soil base of the pseudostem, uprooting the whole stool and control leaving the infected stools. Initial visual assesment before implementation of the orchard was over 80% infection. Later samples were collected for diagnosis of ten plants per treatment from different plant parts and were subjected to ELISA and PCR procedures for confirmion of the presence of Xcm. Rouging options was implemented for one year. During and after experimentation periodic visual assesment of BXW incidence and severity reduced. Results of ELISA assays and PCR results indicated Xanthomonas was present on banana plants. Rouging the infected banana stems by cutting at the base, uprooting and injection of herbicide reduced BXW incidence within six months. Xanthomonas, an inhibiting bacteria cannot surve without host and by killing the banana plant the Xanthomonas dies. Yields were recovered from the rehabilitated orchard within one year. Banana orchard highly infected with BXW was effectively rehabilitated.
Variation of Yield and Chemical Composition of Essential Oil from Cupressus lusitanica Growing in Different Agro-ecological Zones of Rwanda
(Asian Journal of Applied Chemistry Research, 2021-08-25) Nteziyaremye, Papias; Cherutoi, Jackson; Makatiani, Jacqueline; Muhizi, Théoneste
Chemical composition and essential oil contents among essential oil-bearing plants are mostly influenced by different factors including ecological features of habitat. In this study, variation in yield and chemical composition of essential oils (EOs) from the leaves of Cupressus lusitanica Mill. (Cupressaceae) in different regions of Rwanda was investigated. Extraction of essential oils from fresh leaves of C. lusitanica collected in March 2021 and April, 2021 from three different ecological zones of Rwanda, Buberuka highland zone (Burera), Central plateau zone (Huye) and Eastern savannah zone (Kayonza) was realized through steam distillation. The chemical compositions of distilled EOs were analyzed using both Fourier transform infrared (FT-IR) spectroscopy and gas chromatography-mass spectrometry (GC-MS), while their yields were determined by simple calculus. The average yields of the EOs were 0.27 ± 0.02, 0.34 ± 0.02 and 0.39 ± 0.01% (v/w) for Burera, Huye and Kayonza, respectively. Results of FT-IR analysis were confirmed by those of GC-MS analysis, and indicated the presence of different groups of compounds including aliphatic alkanes, carboxylic acids, alkenes, aldehydes, aromatics and ketones in the EOs. GC-MS results revealed that sabinene (20.84%), myrcene (19.63%), α-pinene (10.23%) and δ-3-carene (10.13%) were the dominant chemical constituents for EOs of C. lusitanica from Burera. Umbellulone (24.21%), δ-3-carene (16.76%), sabinene (10.54%) and α-pinene (8.21%) were the main constituents for EOs of C. lusitanica from Huye, while γ-terpinene (18.77%), umbellulone (18.16%), isobornyl acetate (9.972%), and myrcene (7.20%) were the major components of EOs of C. lusitanica from Kayonza. The current results demonstrated an intraspecific variation in content and chemical profile of C. lusitanica EOs from one geographical region to another. The observed variations are mostly due to the interactions of C. lusitanica species with climatic and environmental conditions of ecological habitat. However, it could also be the effects of various biotic factors, as well as maturity of plant and stage of plant growth. Further studies are needed to establish the influence of different geo-climatic and environmental factors on each single major component of C. lusitanica EOs.

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