Free access
Issue
Ann. For. Sci.
Volume 57, Number 4, May 2000
Page(s) 305 - 312
DOI http://dx.doi.org/10.1051/forest:2000121
DOI: 10.1051/forest:2000121

Ann. For. Sci. 57 (2000) 305-312

Influence of the ectomycorrhizas formed by Tuber melanosporum Vitt. on hydraulic conductance and water relations of Quercus ilex L. seedlings

Andrea Nardinia - Sebastiano Salleoa - Melvin T. Tyreeb - Moreno Vertoveca

aDipartimento di Biologia, Università di Trieste, Via L. Giorgieri 10, 34127 Trieste, Italia
bUSDA Forest Service, Northeastern Experiment Station, 705 Spear Street, Burlington, VT 05402-0968, USA

(Received 8 November 1999; accepted 7 February 2000)

Abstract:

The physiological impact of ectomycorrhizal infection was investigated in the association between Tuber melanosporum Vitt. and Quercus ilex L. A number of physiological parameters were investigated on 2-year-old seedlings inoculated for 22 months (I-seedlings) compared to non-inoculated plants (NI-seedlings). I-seedlings had a 100% infection rate in root tips compared to a 25% infection rate in root tips of NI-seedlings. I-seedlings had higher values of net assimilation and stomatal conductance than NI-seedlings. Root hydraulic conductance per unit root surface area of I-seedlings was much reduced to 0.44$\times$ that of NI-seedlings but had 2.5$\times$ more fine root surface area than NI-seedlings. When root conductance was scaled by leaf area, the I-seedlings had 1.27$\times$ the root conductance per unit leaf area compared to NI-seedlings. I-seedlings also had significantly higher hydraulic conductances of shoots with leaves, of shoots without leaves and lower leaf blade hydraulic resistances.


Keywords: hydraulic conductance / water relations / ectomycorrhiza / Quercus ilex L. / HPFM

Résumé:

Influence sur la conductance hydraulique et les relations hydriques des semis de Quercus ilex L. des ectomycorrhizes formées par Tuber melanosporum Vitt. L'impact physiologique dû à l'infection d'ectomycorrhizes a été étudié dans l'association Tuber melanosporum Vitt. et Quercus ilex L. Un certain nombre de paramètres physiologiques ont été mesurés sur des semis de 2 ans inoculés pendant 22 mois (semis-i) en comparaison avec des cultures saines (semis-i). Les semis-i présentent 100% de taux d'infection des racines, tandis que les semis-i atteignent un taux de 25%. Les semis-i ont des niveaux d'assimilation nette plus élevés par rapport aux semis-i. La conductance hydraulique des racines par unité de surface des racines pour les semis-i est réduite de plus de 0,44 fois par rapport aux semis-i, mais comporte une surface de racines 2,5 fois inférieure à celle des semis-i. En rapportant la conductance des racines à la surface des feuilles, la conductance des racines par unité de surface des feuilles des semis-i est 1,27 fois plus élevée que celle des semis-i. Les semis-i présentent également une conductance hydraulique des rameaux avec feuilles et sans feuilles bien plus élevée, ainsi qu'une moindre résistance hydraulique des feuilles.


Mots clé : conductance hydraulique / relations hydriques / ectomycorrhize / Quercus ilex L. / HPFM

Correspondence and reprints: Andrea Nardinia
Tel. +39-040-6763875; Fax. +39-040-568855; nardini@univ.trieste.it

Copyright INRA, EDP Sciences

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