PubMed | International Center for Tropical Agriculture, University of New England of Australia, Kenya Agricultural and Livestock Research Organization and Grains Research and Development Corporation
Type: | Journal: Journal of the science of food and agriculture | Year: 2016
Low rainfall is a major limitation to expanding the dairy industry in semi-arid environments in East Africa. In such dry areas, plants need to keep their tissues hydrated and stomata open for carbon exchange and to grow. On this basis, we assessed the productivity of 10 lines of Napier grass (Pennisetum purpureum Schum.), which formed three yield clusters: low yielding (LYC), moderate yielding (MYC), and high yielding (HYC), in a wet highland (Muguga) and semi-arid lowland (Katumani) of Kenya. Stomatal conductance (gThe plants were less stressed at Muguga, where gThe three water stress indices were poor, whereas vigorous early canopy development (determined as LAI) was a more reliable predictor of productivity potential of Napier grasses. In these dry environments, therefore, early rapid canopy development can be an effective indicator of yield potential and a credible selection criterion. 2016 Society of Chemical Industry.
PubMed | Kenya Agricultural and Livestock Research Organization and Leibniz University of Hanover
Type: Journal Article | Journal: Insects | Year: 2015
Western flower thrips (WFT), Frankliniella occidentalis (Pergande), is an important pest of vegetable crops worldwide and has developed resistance to many insecticides. The predatory mites Neoseiulus (=Amblyseius) cucumeris (Oudemans), the entomopathogenic fungus Metarhizium anisopliae (Metsch.), and an insecticide (imidacloprid) were tested for their efficacy to reduce WFT population density and damage to French bean (Phaseolus vulgaris L.) pods under field conditions in two planting periods. Metarhizium anisopliae was applied as a foliar spray weekly at a rate of one litre spray volume per plot while imidacloprid was applied as a soil drench every two weeks at a rate of two litres of a mixture of water and imidacloprid per m. Neoseiulus cucumeris was released every two weeks on plant foliage at a rate of three mites per plant. Single and combined treatment applications reduced WFT population density by at least three times and WFT damage to French bean pods by at least 1.7 times compared with untreated plots. The benefit-cost ratios in management of WFT were profitable with highest returns realized on imidacloprid treated plots. The results indicate that M. anisopliae, N. cucumeris, and imidacloprid have the potential for use in developing an integrated pest management program against WFT on French beans.
Kega V.M.,Kenya Agricultural and Livestock Research Organization |
Olubayo F.,University of Nairobi |
Kasina M.,Kenya Agricultural and Livestock Research Organization |
Nderitu J.H.,Mount Kenya University
Journal of Entomology | Year: 2016
Information on losses caused by the African white rice stem borer, Maliarpha separatella rag, which is an important rice pest in Kenya is scanty. The development and implementation of effective pest management strategies relies on accurately defined Economic Injury Levels (ElL) for that pest. Investigations were, therefore, conducted to determine yield losses caused byM. separatella and economic injury level of the pest. The experiment was conducted in an insect proof screen house at Kenya Agricultural and Livestock Research Organization, Mwea station. The experiment was arranged as a (2×6) factorial design and each treatment replicated three times. First factor was time of infestation at two levels, early and late which was 3 and 6 weeks after transplant date, respectively. Second factor was infestation rate at six levels (0, 1, 2 4, 6 and 8 egg masses). Results indicated that infestation levels of 1, 2, 4, 6 and 8 M. separatella egg masses at early infestation resulted in grain yield losses of 59.8, 83.2, 84.8 90.2 and 90.9%, while losses of same infestation levels at late infestation was 34.3, 52.1, 63.4, 81.8 and 80.8%. There was a strong positive relationship between yield loss and M. separatella population levels, (y = -0.214.29x+ 1693.4, r2 = 0.8416). On the basis of cost benefit ratio, the economic injury level was 6 and 8 egg masses per square meter in the early and late infestation, respectively. The action threshold for early infestation was 4 egg masses and 6 egg masses for late infestation. © 2016 V.M. Kega et al.
Mo F.,Lanzhou University |
Wang J.-Y.,Lanzhou University |
Xiong Y.-C.,Lanzhou University |
Nguluu S.N.,Kenya Agricultural and Livestock Research Organization |
Li F.-M.,Lanzhou University
European Journal of Agronomy | Year: 2016
In semiarid Kenya, field productivity of maize has been at a low integrity level due to insufficient use of rainwater use. From 2012 to 2013, an innovative ridge-furrow mulching system (RFMs) was tested using local maize (Zea mays L.) hybrid, KCB in KARI-Katumani Farm, Kenya in long and short rainy seasons. Field experiments were conducted in a randomized complete block design with four treatments: 1) RFMs with transparent polyethylene film (RFT), 2) RFMs with black polyethylene film (RFB), 3) RFMs with grass straw mulching (RFS), and 4) RFMs without mulching (CK). Soil moisture & temperature, grain yield, water use and economic benefit were determined and analyzed. The results indicated that both RFT and RFB treatments significantly increased soil water storage amount in the depth of 0–60 cm. Grain yield and water use efficiency (WUE) in both treatments were increased by 66.5–349.9% and 72.9–382% respectively, compared with those of CK over two growing seasons. In addition, grain yield and WUE in RFS treatment were only increased by from 4.2–127.1% compared with those of CK. Particularly, two types of plastic films displayed different effects on modifying topsoil temperature. Transparent film mulching significantly increased topsoil temperature by 1.3 °C (p < 0.05) higher than CK, to facilitate growth and grain formation in long (but cool) growing season. In contrast, black film mulching lowered soil temperature by 0.3 °C lower than CK in short (but warm) growing season, which led to better soil thermal balance. Overall, RFMs with film mulching could serve as an effective solution to increase maize productivity, and hence a promising strategy to cope with food security under climate change in semiarid Kenya. © 2016 Elsevier B.V.
Gemenet D.C.,University of Hohenheim |
Gemenet D.C.,Kenya Agricultural and Livestock Research Organization |
Hash C.T.,International Crops Research Institute for the Semi Arid Tropics ICRISAT |
Sanogo M.D.,Institute dEconomie Rurale IER |
And 4 more authors.
Field Crops Research | Year: 2015
Pearl millet [. Pennisetum glaucum (L.) R. Br] production on the acid sandy Sahelian soils in West Africa (WA) is severely limited by low plant-available phosphorus (P) in addition to erratic rainfall. We sought to examine the genetic variability for P uptake and P utilization efficiency in 180 WA pearl millet inbred lines or subsets thereof under low (LP) and high P (HP) conditions in one field and two pot experiments, determine the relationships among the measured traits and grain yield under field conditions at three other independent WA sites, and identify potential secondary selection traits for improving grain yield under LP. We observed genetic variation for P uptake and utilization in both seedling and mature plants. P utilization efficiency increased under LP conditions. Total P uptake was more important for grain production than P utilization under LP field conditions (. r=. 0.57*** vs r=. 0.30***). The estimated response to indirect selection was positive for most of the measured morphological and P-efficiency parameters. We conclude that both seedling and mature plant traits are potentially useful as secondary traits in selection of pearl millet for low-P adaptation. These results should be validated using heterozygous pearl millet genetic materials. Ultimately, pearl millet breeding activities for low P tolerance in WA should be integrated with other system-oriented research such as nutrient cycling, intercropping or rotations with legumes, better crop-tree-livestock integration, and modest applications of locally available rock phosphate. © 2014 Elsevier B.V.
Kagunyu A.F.,Kenya Agricultural and Livestock Research Organization |
Wanjohi J.G.,Catholic University of Eastern Africa
Pastoralism | Year: 2015
This study took place in Isiolo County in northern Kenya among the Borana community, whose major economic activity is livestock production. The County is characterized by droughts which have increased in frequency and severity. This study sought to investigate the availability of camel drought feeds in the study site, guided by two specific objectives: to establish the existence of supplementary feeds used by the Borana community for camels during the drought periods and to establish the distribution of the supplementary feeds. Data was collected through secondary sources, semi-structured interviews, focus group discussions and direct observation. The study findings indicate that the Borana pastoralists use Euphorbia tirucalli to feed their camels during the drought periods. They also revealed that the plant was sparsely distributed in the study site and most of the feeds were purchased from neighbouring agro-pastoralists at affordable prices. E. tirucalli plays a very important role in saving the lives of camels during drought periods. Therefore, this study recommends that pastoralists in Isiolo County need to be encouraged to plant E. tirucalli in their farms. The Borana pastoralists need to be trained on appropriate methods of harvesting and propagating the plant. © 2015, Kagunyu and Wanjohi.
Kiarie S.M.,Egerton University |
Karanja L.S.,Kenya Agricultural and Livestock Research Organization |
Obonyo M.,Egerton University |
Wachira F.N.,Association for Strengthening Agricultural Research in East and Central Africa ASARECA
Acta Horticulturae | Year: 2016
Sweet potato is a major source of dietary carbohydrate and a key food security crop in Kenya. Production of orange-fleshed sweetpotato (OFSP) in Kenya is constrained by sweetpotato virus diseases whose synergistic interaction between two virus families, sweetpotato feathery mottle virus (SPFMV) and sweetpotato chlorotic stunt virus (SPCSV). The absence of disease tolerant varieties contributes to yield losses of up to 98% that are currently observed. Research efforts in the past have concentrated on detection methods and epidemiological studies of viral infection. However, studies on the changes in quantitative contents of ß-carotene, dry matter, iron and zinc to virus infection in the OFSP varieties is prerequisite to development of virus tolerant varieties. For this reason the current study aimed at determining the effect and interaction of multiple virus infection with ß-carotene, iron and zinc levels in OFSP. Nitrocellulose membrane Enzyme-Linked Immunosorbent Assay was used to screen 10 viruses infecting OFSP. Reverse Transcriptase-PCR (RT-PCR) confirmed absence of SPCSV and SPFMV. Ninety virus free clones from six families were selected and planted in the field in a complete randomized design with three replicates. Natural virus transmission by vectors white flies (Bemisia tabaci) and aphids was allowed to occur. The plants were maintained until storage roots were formed. Clones with virus tolerance were selected. ß-carotene was quantified on root samples using Ultraviolet spectrophotometer. Atomic absorption spectrum was used to quantify Iron and zinc. Dry matter was analysed using American Association of Cereal Chemists (AACC) method. Analysis of variance (ANOVA) for effect of virus infection on ß- carotene, iron and zinc levels showed that there were no significant differences (P<0.05) among all the means on the clones used. Data was analyzed by using ANOVA (SAS Inc. 2006) then separation of means using LSD. Regression analysis revealed that the average virus score did not have an effect on dry matter and micronutrients. ANOVA revealed significant differences in dry matter among families (P<0.05). No significant differences were found among replicates. Among replicates and families, significant difference in iron content was identified (P<0.05). Disease severity scores and zinc levels among the test samples were not significant among replicates and families. There was significant differences in ß-carotene levels (P<0.05) in families but not in replicates. Separation of means displayed significant differences in iron, dry matter content and ß carotene levels among the test genotypes. The findings of the study will contribute and enhance the understanding of the effects of sweetpotato viruses on quality and quantity in OFSP and enable development of virus tolerant varieties with quantified qualitative attributes. © ISHS.
PubMed | University of the Free State, Kenya Agricultural and Livestock Research Organization, University of Arizona and U.S. Department of Agriculture
Type: Journal Article | Journal: TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik | Year: 2016
A gene for Ug99 resistance from wheat landrace CItr 4311 was detected on the long arm of chromosome 2B. Wheat landrace CItr 4311 has seedling resistance to stem rust caused by Puccinia graminis f. sp. tritici race TTKSK and field resistance to the Ug99 race group. Parents, F
Gichangi E.M.,Kenya Agricultural and Livestock Research Organization |
Gatheru M.,Kenya Agricultural and Livestock Research Organization |
Njiru E.N.,Kenya Agricultural and Livestock Research Organization |
Mungube E.O.,Kenya Agricultural and Livestock Research Organization |
And 2 more authors.
Climatic Change | Year: 2015
A study was conducted to investigate the intra-seasonal climate variability and change in semi-arid eastern Kenya and also assessed the ability of the households to discern trends in climate and how the perceived trends converge with actual long term weather observations. The study utilised long term climatic data and data collected through interviews of 200 households using a structured questionnaire. The survey data was analysed through descriptive statistics using the Statistical Package for Social Sciences (SPSS) version 12.0. The results of long term climatic data indicated high year-to-year variation in seasonal rainfall with 49.0% and 58% negative anomalies observed in the long and short rainfall seasons respectively. No discernible increasing or decreasing trend in the long- seasonal rainfall was observed over the period of study. However, Long-term temperature data showed high year-to-year variation in annual mean maximum and minimum temperatures with maximum temperature increasing during the period. Long term rainfall data (51 years) showed that 31.4 and 35.3% of the long rains would be classified as good and failed seasons respectively, with the remaining percentage classified as moderate seasons. For the short rains, 15.7 and 43.1 % would be classified as good and failed seasons respectively, with the remaining percentage classified as moderate seasons. Farmers interviewed were able to recollect the past seasons fairly accurately especially the ‘good’ and ‘failed’ seasons which corroborated well with the meteorological records. Indigenous knowledge on weather forecasting was reported by 81% of farmers to be helpful in farming decision making especialy on the types of crops to be planted. A better understanding of farmers’ perceptions of climate change, ongoing adaptation measures, and the decision-making process would important to inform policies aimed at promoting sustainable adaptation of the agricultural sector. © 2015, Springer Science+Business Media Dordrecht.
PubMed | Kenya Agricultural Research Institute, Kenya Agricultural and Livestock Research Organization, University of Nairobi and Kenya International Livestock Research Institute
Type: | Journal: Preventive veterinary medicine | Year: 2016
A cross-sectional study to determine risk factors associated with sero-prevalence of contagious caprine pleuro-pneumonia (CCPP) in goats was carried out between the months of March, 2014 and March, 2015 in Pokot East, Turkana West and Kajiado Central Sub-counties. A semi-structured questionnaire focusing on risk factors for CCPP was completed for each flock whose serum samples were collected. A logistic regression model was developed to assess the association between the risk factors and CCPP sero-positivity. Of the 54 flocks, 49 (90.7%) presented at least one sero-positive animal. Two hundred and four of the 432 goats tested sero-positive at monoclonal antibody based competitive Enzyme-linked immuno-sorbent assay (c-ELISA), hence a sero-prevalence of 47.2% (95% CI=42.5-51.9). Previous exposure of flocks to CCPP (p<0.001, OR=52.8; CI=6.45, 432), distant sources of veterinary drugs (p<0.001, OR=6.17; CI=3.41, 11.1), movement of goats to dry season feeding areas (p<0.001, OR=4.31; CI=2.39, 7.75) and markets as a source of new introductions to the flock (p=0.033, OR=1.86; CI=1.05, 3.27) were identified as risk factors significantly associated with CCPP sero-prevalence. The findings provide further evidence supporting the high prevalence and endemic state of the disease in pastoral flocks and hence there is need for adequate measures to be put in place to control the disease effectively.