JXB Advance Access first published online on June 1, 2007
This version published online on August 11, 2007
Journal of Experimental Botany, doi:10.1093/jxb/erm117
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© 2007 The Author(s).
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/2.0/uk/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.This paper is available online free of all access charges (see http://jxb.oxfordjournals.org/open_access.html for further details)
RESEARCH PAPER |
Evaluation of drought response of two poplar clones (Populusxcanadensis Mönch I-214 and P. deltoides Marsh. Dvina) through high resolution analysis of stem growth
1Laboratorio Xilogenesi, Istituto Valorizzazione Legno e Specie Arboree, IVaLSA–CNR Via Madonna del Piano, 50019 Sesto Fiorentino (FI), Italy
2Dipartimento Territorio e Sistemi Agro-Forestali, Università degli Studi di Padova, Viale dell'Università 16, 35020 Legnaro (PD), Italy
3Istituto di Sperimentazione per la Pioppicoltura–CRA, Strada per Frassineto, 15033 Casale Monferrato (AL), Italy
* To whom correspondence should be addressed. E-mail: giovannelli{at}ivalsa.cnr.it
Different irrigation effects on stem radius variation (
R) and maximum daily shrinkage (MDS) in Populus deltoides Dvina and Populusxcanadensis I-214 were studied to assess differences in drought tolerance between clones. One-year-old trees growing in concrete tanks were submitted to two irrigation regimes (natural rainfall and irrigation) from 24 June to 10 August, and
R was monitored by automatic point dendrometers. Independently of the irrigation regime, Dvina showed a higher stem radial increment than I-214. In both clones, the first response to changed soil water content was a significant increase in MDS, whilst
R decreased about 20 d later when pre-dawn leaf water potential (
pd) dropped below –0.4 MPa. However, they displayed different strategies to overcome drought. Dvina maintained a positive
R for longer than I-214, which had lower leaf
pd and greater leaf abscission at the end of the drought period. After irrigation resumed, Dvina showed a higher capacity to restore stem growth. I-214 was probably unable to recover secondary growth because of higher leaf abscission during drought stress and the production of newly expanded leaves during recovery. It is concluded that the larger radial growth of Dvina derived from a better water use (carbon uptake versus water loss) than I-214 under limited water availability.
Key words: Dendrometer, drought tolerance, fast-growing species, hybrid poplars, maximum daily shrinkage, radial growth
This is a new version as the first version of the article was not Open Access.
Received 26 March 2007; Revised 27 April 2007 Accepted 1 May 2007