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University of Copenhagen (2014)

Improving and conserving sahelian fruit trees : a case study of Parkia biglobosa Jacq. (Benth.)

Ouedraogo Moussa

Titre : Improving and conserving sahelian fruit trees : a case study of Parkia biglobosa Jacq. (Benth.)

Auteur : Ouedraogo Moussa

Université de soutenance : University of Copenhagen, DK

Grade : Doctor of Philosophy (PhD) 2014

Résumé
Native Sahelian fruit trees are well known for their economic value and their nutritional importance for local populations. Their products are a source of income and a source of calories, vitamins, minerals and antioxidants, especially vital for children. Fruit trees are crucial for the people in West Africa Sahel during the food shortage period, lasting 6-8 months a year in this region. However, the availability of fruit trees is declining due to increased demographic pressure and climate variability (drought) that is occurring with increasing frequency and intensity. Besides compromising the availability of important resources for rural people, reduced abundance of target species can lead to loss of genetic variation within species, which again can reduce the capacity of trees and shrubs to adapt to environmental change and reduce the gain farmers can realize from selection. Parkia biglobosa is among the top five priority indigenous tree species in the Sahel and one of the priority research species in Burkina Faso. Several studies have been made since the 1980’s. The present thesis is about breeding and conservation of this species and addresses four specific aspects : •Performance of provenances in field trials ; •Genetic structure of P. biglobosa in its natural range in West and Central Africa based on leaf morphology and molecular markers ; •Variation between provenances in phenology ; •An approach for utilisation of P. biglobosa genetic resources and a conservation strategy in Burkina Faso. The study of provenance performance is based on analyses of survival and growth traits in two international provenances trials, located in the north Sudanian zone (Gonsé) and south Sudanian zone (Dinderesso) in Burkina Faso, respectively. Evidence of substantial genetic differentiation between 25 studies populations within West Africa is provided. The findings support a hypothesis of a continuum of locally adapted populations that allows the species to thrive under quite different climatic conditions across West Africa. New insights are presented on the genetic structure of P. biglobosa through its distribution area in West and Central Africa, based on variation in morphological traits and chloroplast haplotypes. The study on variation in phenology between provenances confirmed that significant genetic variation exists among the provenances of P. biglobosa in flushing, flowering and fruiting traits and careful choice has to be made when selecting the provenances for seed orchards. The PhD project leads to the initiation of a programme for conservation and use of genetic resources of P. biglobosa in Burkina Faso through germplasm collection and breeding seed orchard establishment. The germplasm collection was undertaken based on seed collected from selected plus trees and a progeny test was initiated to increase knowledge about the genetic study of the species, and estimate genetic parameters to be used for future breeding activities. The present findings on the species’ genetic diversity, its genetic structure in natural populations and the genetic gains that can be obtained through selection and breeding, constitute a good start to strengthen the improvement programme of P. biglobosa. The strategy proposed for seed deployment and for development of the breeding zones in Burkina Faso is expected to lead to a better utilization and conservation of the genetic potential. The principles of this applied approach can be extended to the regional level as the Sahelian countries are experiencing the same climatic conditions

Présentation

Page publiée le 9 décembre 2014, mise à jour le 17 juillet 2017