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Title: Arbuscular Mycorrhizal Fungal diversity of Coffee and Shade trees of Bonga forest, South Western Ethiopia
Authors: Tadesse, Chanie
Date Added: 4-Sep-2007
Abstract: To date, information regarding densities and identification of dominant coffee shade trees and explanation of their interaction with physical parameters in southwestern part of Ethiopia is extremely very scanty. Moreover, mycorrhizal fungi spore densities, colonization rate, diversity and interaction with physical and chemical parameters of soil are not evaluated in any of the coffee forest in the country and this work is to bridge such information gap. So, reconnaissance survey was conducted and the number of coffee and coffee shade tree species was counted with in a 20m x 20 m quadrat. Spores were separated from the bulk of the soil by the wet sieving and decanting method followed by sucrose centrifugation and counted per 100 g dry soil. Percent root colonization was determined clearing the root segments in 10 % KOH and stained with 0.05 % trypan blue.During the reconnaissance survey extremely large number of coffee seedlings and saplings were observed in the study area. Olea capensis, Schefflera abyssinica, Phoenix reclinata and Prunus africana were encountered as dominant shade tree species with percentage occurrences of 15, 12, 11 and 10 %, respectively. Milletia ferruginea, Albizia gummifera, Cordia africana, Croton macrostachyus and Dracaena steudneri comprise 40 % of the total number of plant species. Twenty four percent of the dominant shade trees were principally represented by leguminous trees such as M. ferruginea and A. gummifera. Arbuscular mycorrhizal fungal status was also investigated. Investigation of roots and rhizosphere soils of 14 shade tree species, M. ferruginea, S. abyssinica, C. macrostachyus, Ficus vasta, A. gummifera, O. capensis, C. africana, Ehretia abyssinica, Pouteria adolfi-friederici, Pavetta oliveriana, Ficus sur, P. africana, P. reclinata and Polyscias fulva, and the coffee tree underneath revealed arbuscular mycorrhizal colonization and different types of AM spores. The number and morphological type of spores were determined in 100g of rhizosphere soil. All species had a high level of AM colonization. F. vasta, C. macrostachyus, S. abyssinica and O. capensis spp. had the highest level of colonization. E. abyssinica, P. africana and P. fulva exhibited the lowest level of colonization. The coffee trees revealed generally maximum colonization than respected shade trees. The number of spores forming AM in all rhizosphere soils ranged between 578-1313 spores/ 100g of dry soil. Spores were grouped in four principal morphological types Glomus, Gigaspora, Scuttelospora and Acaulospora in descending order of relative abundance, respectively. Spore density and colonization percentage were found to be negatively correlated with O.C, total N, available P, EC and Zn. Population of spore types were also some how determined by soil physical and chemical properties. Arbuscular Mycorrhizal fungi are commonly considered to be non specific with respect to their host and their ability to colonize particular plant species. Conversely, it is investigated that plant species differ in their ability to form and benefit from mycorrhizal relationship. This study didn’t investigate the whole range of organisms in the rhizosphere which could give benefits to trees. So, it is difficult to draw conclusion that the well being of the shade trees and coffee plants in the natural forest is due to only AMF colonization. However, AMF could be considered to be a future tool in agriculture, i.e. fertilizer substitute and as biocontrol agent. So, it is recommended that: (a) studying the ecology, diversity and host range of AMF is of enormous importance before application. (b) their relation with nutrient dynamics and other soil characteristics should be evaluated before use. (c) these organisms should receive the proper management. (d) the impact of litter fall on AMF spore density and diversity should be evaluated in the future. Finally, this symbiosis command great interest as the subject of future research with relation to food security.
Description: A Thesis Submitted to the school of graduate studies Department of Biology In partial fulfillment of the requirements of the degree of Master’s of science in Biology, Applied Microbiology
URI: http://hdl.handle.net/123456789/60
Appears in:Thesis - Biology

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