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University of Nairobi (2011)

Effects of soil physicochemical properties and genetic characteristics on distribution of acacia senegal (L) willd. varieties in the dryland areas of Kenya

Githae, Eunice Wamuyu

Titre : Effects of soil physicochemical properties and genetic characteristics on distribution of acacia senegal (L) willd. varieties in the dryland areas of Kenya

Auteur : Githae, Eunice Wamuyu

Université de soutenance : University of Nairobi

Grade : Doctor of Philosophy (PhD) 2011

Résumé
Acacia senegal is a dryland multipurpose tree species highly valued for gum Arabic production, agroforestry and desertification control. The aim of this study was to investigate the edaphic and genetic factors that affect distribution of the three Kenyan indigenous varieties (A. senegal var. senegal, var. kerensis and var. leiorhaehis) for the purpose of conservation of genetic resources and improvement of smallholder livelihoods in the drylands of Kenya. In the first part of research, inter-simple sequence repeat (ISSR) and chloroplast micro satellites (cpSSR) markers were used to study genetic diversity among seven Kenyan populations of A. senegal (Kajiado, Magadi, Kibwezi, Ntumburi, Ngarendare, Daaba and Kulamawe) embracing the three putative varieties. In the second part, soil physicochemical properties were assessed by collecting soil samples under the canopies of the three varieties taking into account distance from the trunks (0, 1 and 2 m) at a depth of 0 - 25 em and comparing with the soils from the open canopies. The third part estimated the potential of the three varieties to fix nitrogen in their natural ecosystems using 15N natural abundance method using two reference species namely ; Balanites aegyptiaea and Commiphora africana. The study was conducted in the arid and semi arid lands of Kenya. The two molecular markers detected similar levels of Nei’s gene diversity (HISSR= 0.211, HcpSSR= 0.212) among the A. senegal populations. Analysis of molecular variance (AMOV A) detected significant genetic variations within and among populations (Psicocaemica\. ’Q’to’Qerties aro.o the tmee varieties (f

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Page publiée le 23 novembre 2013, mise à jour le 23 février 2018