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University of Toronto (1993)

Provenance variation in drought tolerance in Acacia tortilis Forsk. Hayne

Kireger, Eliud Kiplimo

Titre : Provenance variation in drought tolerance in Acacia tortilis Forsk. Hayne

Auteur : Kireger, Eliud Kiplimo

Université de soutenance : University of Toronto

Grade : (M.Sc.F.) 1993.

Résumé
Physiological variation and its correlation with drought tolerance and faster growth were studied in 6 seed provenances of Acacia tortilis (Forsk.) Hayne originating from areas of varying aridity in Kenya. Three provenances were selected for more detailed comparison of longer-term drought effects on growth, carbon partitioning and physiological characteristics. Provenances varied in their growth and physiological responses to drought depending on their climate of origin. Compared with more mesic ones, provenances from drier sites exhibited : (i) low stomatal conductance under drought, and (ii) grew faster under drought, had a higher survival, allocated more biomass to roots relative to the shoot, and their leaf area growth was less affected by drought. The results suggest that provenances capable of faster growth under drought were more drought tolerant, and their better survival rate was correlated with greater relative allocation of biomass to the root and lower stomatal conductance. Faster rates of biomass production under drought were largely the result of less inhibition of leaf growth, higher rates of photosynthesis and faster recovery after rehydration. It was concluded that dehydration postponement mechanisms were more important than tolerance adaptation for seedling survival under severe drought. These physiological characteristics may provide criteria that can be used for early selection of more vigorous drought tolerant Acacia tortilis genotypes for drought prone sites and for matching seed sources with planting sites in Kenya

Présentation (Research Kenya)

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