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The selection of fast growing trees for sustainable production in the semi-arid zone : growth, N2 fixation and microbiology, soil amelioration, whole plant physiology, genetics, water and nutrient use

Objective



This multidisciplinary research project aims to identify fast growing tree species and their associated microsymbionts which perform functions and produce materials of immediate benefit to rural populations. Growth of native Sahelian and exotic Nz fixing and non-N2 fixing trees will be compared in existing 9 and 14 year-old replicated and blocked trials in Senegal and on similar replicated existing stands in Cameroun. Soils beneath each species will be sampled to a depth of 1m to assess soil amelioration and to 2m for root distribution. The latter will enable potential root competition with crop plants to be assessed. Estimates of nutrient removal through wood and fodder harvesting will give insight into nutrient budgets and long term sustainability. Molecular biological techniques, RFLP, PCR, RAPDS etc. will be used to identify and characterise strains and species of Rhizobium originating in differing regions of the Sahel. These will be inoculated onto seedlings and their effectiveness in N2 fixation and growth promotion will be assessed. Molecular methods will be used to assess the competitiveness and persistence of selected inoculants after planting in the field and to characterise genetic variation in Acacia senegal to seek molecular markers involved in host/symbiont signalling systems. Similarly, molecular markers for fast growth and N2 fixation will be sought among the strains of Rhizobium.
Stable isotope techniques will be used to assess N2 fixation and water use efficiency. The suggestion that VA and ectomycorrhizas influence results of ô15N nitrogen fixation estimates, will be investigated. Water use will be monitored using neutron probe and sap-flow measuring systems.
The effects of competition induced light reduction on photosynthesis and hence on N2 fixation will be assessed.

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

NATURAL ENVIRONMENT RESEARCH COUNCIL
Address
C/o Bush Estate
EH26 0QB Penicuik
United Kingdom

Participants (5)

Institut Français de Recherche Scientifique pour le Développement en Coopération (ORSTOM)
France
Address
213 Rue Lafayette
75480 Paris
Institut Sénégalais de Recherches Agricoles
Senegal
Address
Route Des Pères-maristes
Dakar
Office National de Développement des Fôrets
Cameroon
Address

Mbalmayo
UNIVERSITY OF DUNDEE
United Kingdom
Address
Nethergate
DD1 4HN Dundee
University of Helsinki
Finland
Address
9,Viikinkaari
00014 Helsinki