Animal Production and Range Management

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Animal Production and Range Management Department of Faculty of Agriculture and Environment Gulu University

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Browsing Animal Production and Range Management by Author "Alicai, Titus"

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    Genetic Diversity in Napier Grass (Pennisetum purpureum) Assessed by SSR Markers
    (Canadian Center of Science and Education, 2015-06-15) Kawube, Geofrey; Alicai, Titus; Wanjala, Bramwel; Njahira, Moses; Awalla, Juma; Skilton, Robert
    Understanding of genetic diversity among Napier grass is very important for selection and improvement of Napier grass breeding population. This study determined the genetic diversity among the farmer preferred, wild(local) and selected ILRI gene-bank Napier grass clones using 23 SSR markers selected from pearl millet, maize and sorghum. The results indicated polymorphism among the SSR markers, revealing a total of 339 alleles of which 27.1% alleles were unique, occurring either only in local, farmers-preferred or ILRI clones. Similarly, genetic diversity and observed heterozygosity were highest in the local than in farmers’ preferred and least in the ILRI gene-bank clones. The clones clustered in two groups with a few overlaps, although most of the farmer’s grown Napier grass clones grouped with those from ILRI genebank and clone P99, emphasizing their genetic relatedness. Therefore, the unique alleles revealed in the local clones may be associated with adaptability to local environments. These alleles could, therefore, be exploited for genetic improvement of the farmer-preferred Napier grass.
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    Napier grass stunt disease prevalence, incidence, severity and genetic variability of the associated phytoplasma in Uganda
    (Elsevier Ltd., 2015-04-30) Kawube, Geofrey; Talwana, Herbert; Nicolaisen, Mogens; Alicai, Titus; Otim, Michael; Kabirizi, Jolly; Mukwaya, Anthony; Nielsen, Steen Lykke
    The prevalence, incidence and severity of Napier grass stunt disease (NGSD) caused by phytoplasma on Pennisetum purpureum, the main fodder for livestock under intensive and semi-intensive management systems in Uganda were determined following a field survey carried out in 17 districts. A total of 298 Napier grass fields were visited and NGSD status visually assessed and 1192 samples collected for identification and confirmation of the phytoplasma by polymerase chain reaction (PCR) assays using universal primers P1/P6 nested with R16F2n/R16R2n and, tuf primers 890/340 nested with 835 and 400. From these, 221 PCR products were sequenced and sequences aligned. Napier grass stunt disease is widely spread at an epidemic proportion, with the districts at different risk levels. The most affected districts are in central, East and North parts of the country while those in the west are least affected. Sequence alignments and Blast searches showed that the phytoplasma causing NGSD in Uganda belonged to the phytoplasma group 16SrXI, with single nucleotide sequence variants in a few districts. Therefore, there is a need for development of an area wide NGSD management strategy to contain the disease.
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    Temporal Dynamics of Napier Grass Stunt Disease as Influenced by Napier Grass Clones and Initial Inoculum
    (merican Journal of Experimental Agriculture, 2015-05-09) Kawube, Geofrey; Talwana, Herbert; Alicai, Titus; Otim, Michael; Mukwaya, Anthony; Kabirizi, Jolly
    Napier grass stunt disease (NGSD) is the main biotic factor limiting Napier grass production in the East African region. Its management is, however, hampered by inadequate epidemiological information. This study determined the temporal spread of NGSD in Napier grass fields. A field experiment was setup at National Crops Resources Research Institute, Namulonge in Uganda to determine the influence of initial inoculum and clones on the spread of NSD in the field. The experiment was arranged in a randomized Complete Block Design and replicated 4 times. The initial inoculum levels used were 0%, 10%, 20% and 30% while the clones included KW4, local/wild type and P99, respectively. Napier grass stunt disease incidence data was recorded at 60 days intervals starting 90 days after planting up to 450 days. Napier grass was cut back to a height of 5 cm above ground after each data collection. Gompertz model was found to adequately describe NGSD temporal spread, the basis on which all incidence data was transformed. Results indicate that NGSD symptoms appeared in the field after 150 days after planting. However, NGSD incidence at the time was influenced by initial inoculum levels and type of clone. Plots with higher levels of initial inoculum density reached epidemic levels faster than those without. Disease incidence increased with increase in levels of initial inoculum and time, doubling after every 13.8 to 29.8 days, as such the rate of disease spread is moderate. The disease progression was fastest in clone P99 followed by KW4 and least in local. Final NGSD incidence and Area Under Disease Progress Curve (AUDPC) were linearly related with the NGSD incidence at the time the disease was first detected; indicating that incidence at NSD detection can be used to predict the final disease and AUDPC in the field. Therefore, deployment of measures that reduce initial inoculum is important in control of the disease.