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Do mycorrhizas improve tropical tree seedling performance under water stress and low light conditions? A case study with Dicorynia guianensis (Caesalpiniaceae)

Published online by Cambridge University Press:  27 June 2005

Moïse Béreau
Affiliation:
UMR Ecofog – BP 709, 97387 KOUROU Cedex, French Guiana
Damien Bonal
Affiliation:
UMR Ecofog – BP 709, 97387 KOUROU Cedex, French Guiana
Eliane Louisanna
Affiliation:
UMR Ecofog – BP 709, 97387 KOUROU Cedex, French Guiana
Jean Garbaye
Affiliation:
UMR Interactions Arbres/Microorganismes, 54280 CHAMPENOUX, France
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Abstract

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We tested the response of seedlings of Dicorynia guianensis, a major timber tree species of French Guiana, to mycorrhizal symbiosis and water limitation in a semi-controlled experiment under natural light conditions. Under well-watered conditions, mycorrhizal colonization resulted in an increase of net photosynthesis, growth and phosphorus uptake. When submitted to water stress, no growth reduction of mycorrhizal seedlings was observed. Mycorrhizal seedlings were more sensitive to drought than non-mycorrhizal ones in terms of carbon assimilation, but not with regard to stomatal closure. In contrast to previous studies on temperate tree seedlings, this result precludes a mycorrhizal effect on the hydraulic properties of this species. Furthermore, our results suggest that below a specific threshold of soil moisture, carbon assimilation of D. guianensis seedlings was decreased by the mycorrhizal symbiosis. This is probably related to the competition between the plant and its host fungus for carbon allocation under low light intensity, even though it did not seem to have a significant effect on mortality in our experiment.

Type
Research Article
Copyright
2005 Cambridge University Press