Variability of water use efficiency in FaidheriJia alhida Del. seedlings: comparison of seven panafrican seed origins
Faidherbia albida Del (Mimosoidaea) is a multi-purpose tree frequently used in association with annual crops under semi arid climates in the Sudanian-Sahelian regions of Western Africa. Its most striking feature consists of a reverse phenology, e.g., it drops its leaves at the begiruùng of the rain season, and displays bud burst at the beginning of the dry season. Many observations suggest a phreatophytic behaviour, relying on deep soil water. During seedling establishment however, an active root growth associated with a limited shoot growth, ensures a rapid access to water reserves. During this phase, seedlings may encounter drought conditions, and a differential ability to cope with this stress may explain differences in the success of diverse origins in plantation trials. We designed an experiment to estimate water use efficiency ( as a potentially important factor of adaptability) of seedlings from seven origins covering the whole natural range of the species. Seedlings were grown in pots in a greenhouse at Nancy, France, and their growth and water use were monitored during 6 months. A controlled drought was imposed to half of the seedlings during the two last months. Net assimilation rates and stomatal conductances were monitored on several plants per treatment. At the end of the experiment, biomass, total leaf area, and the ratio 13C/12C were measured, yielding estimates of growth efficiency, integrated water use efficiency, mean 13C discrimination and intrinsinc water use efficiency. The results displayed important interprovenance differences in vigour, a high growth efficiency correlating well with a high water use efficiency. Moreover, F. albida displayed a very low tolerance to drought, with important stomatal closure as soon as the relative extractable soil water and predawn leaf water potential decreased moderately. The significance of these results will be discussed in terms of adaptation of the different provenances to afforestation conditions in Western Africa.
| Main Authors: | , , |
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| Format: | conference_item biblioteca |
| Language: | eng |
| Published: |
INRA
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| Online Access: | http://agritrop.cirad.fr/604119/ http://agritrop.cirad.fr/604119/1/ID604119.pdf |
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