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Australian National University (1993)

Geographical variation and physiological studies in Faidherbia albida (Del.) A. Chev. syn (Acacia albida del. )

Marunda, Crispen Takuranei

Titre : Geographical variation and physiological studies in Faidherbia albida (Del.) A. Chev. syn (Acacia albida del. )

Auteur : Marunda, Crispen Takuranei

Université de soutenance : Australian National University

Grade : Master of Science 1993

Résumé partiel
Faidherbia albida (DEL.) A. Chev. syn (Acacia albida DEL.) is widely distributed in Africa and parts of the Middle East. Its use in traditional agroforestry systems is well known and its potential in reforesting degraded lands is being evaluated in arid regions of many countries. Geographic pattern of variation of the species in Africa was studied to provide a basis for initiating a genetic improvement strategy. The influence of different environments on phenology and growth, and root morphology and size were studied to understand the growth patterns of the species. To test for the extent of genetic variation, twenty provenances were grown in a glasshouse and twenty-four traits assessed. There was strong evidence of genetic variation between provenances and to some extent, between families-within-provenances. Most of the traits showed a north to south trend, with south-east Africa provenances having high growth rates (in · terms of height, root collar diameter and dry weight production) whereas, north-west provenances had qualities of adaptive significance (in terms of late leaf senescence, large root to shoot and leaf to stem ratios). A few traits showed random variation. The patterns of variation were strongly related to the temperature of seed origin and the type of ecosystem in which the species grows naturally. There were strong negative relations between growth traits and those of adaptive significance. Canonical variate analysis showed that the provenances of F. albida from Africa could e grouped into three regions. The groups fall into upland ecosystem of north-west Africa, the riparian ecosystem of south-east Africa and the Sudan/Ethiopian highlands and adjacent Lodwar valley in Kenya (proposed centre of origin).

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