© 2003 Heron Publishing—Victoria, Canada
Impact of successive drought and re-watering cycles on growth and specific leaf area of two Populus × canadensis (Moench) clones, ‘Dorskamp’ and ‘Luisa_Avanzo’
Nicolas Marron (1), Erwin Dreyer (2), Eric Boudouresque (1), Didier Delay (1), Jean-Michel Petit (1), Francis M. Delmotte (1) and Franck Brignolas (1, 3)
1. Laboratoire Biologie des Ligneux et des Grandes Cultures, UPRES EA 1207, UFR-Faculté des Sciences, Université d’Orléans, rue
de Chartres, BP 6759, 45067 Orléans Cedex 02, France / 2. UMR INRA-UHP, Ecologie et Ecophysiologie Forestières, INRA Nancy, 54380 Champenoux, France / Author to whom correspondence should be addressed (franck.brignolas@univ-orleans.fr) / Received March 11, 2003; accepted May 26, 2003; published online November 17, 2003
Summary
Responses to successive drought and re-watering cycles (1–3 cycles) were compared in greenhouse-grown cuttings of Populus × canadensis (Moench) clones, ‘Luisa_ Avanzo’ and ‘Dorskamp.’ Total leaf number increment rate, duration of leaf expansion, total and
individual leaf area expansion rates and stomatal conductance were recorded periodically during the experiment. Soil water
content (SWC) and predawn leaf water potential (ΨWP) were measured four times during each drought cycle. In parallel, relative leaf water content (RWC) and specific leaf area
(SLA) were estimated on leaves collected from the top to bottom of each cutting. Under well-watered conditions, ‘Luisa_Avanzo’
and ‘Dorskamp’ differed in their patterns of leaf area expansion. Although duration of leaf expansion was similar between
clones, ‘Luisa_ Avanzo’ exhibited higher total leaf number increment rates and individual leaf area increases than ‘Dorskamp.’
As a result, ‘Luisa_Avanzo’ cuttings reached larger individual and total leaf areas than ‘Dorskamp.’ ‘Dorskamp’ leaves had
lower SLA than ‘Luisa_Avanzo’ leaves. In response to successive drought cycles, both clones underwent decreases in total leaf
number increment rates and in total leaf area expansion rates, but both whole-plant and individual leaf areas were drastically
reduced only in ‘Luisa_Avanzo.’ ‘Dorskamp’ maintained a constant leaf area as a result of an increase in the duration of leaf
expansion during drought and a significant stimulation of individual leaf area expansion rate and total leaf number increment
rate in response to re-watering. Drought caused a greater decrease in SLA in ‘Luisa_Avanzo’ than in ‘Dorskamp.’ Expanded leaves
of ‘Dorskamp’ were constitutively dense or thick, or both, whereas leaves of ‘Luisa_Avanzo’ became dense or thick, or both,
only in response to drought. In both clones, re-watering caused partial recovery of SLA to control values. Our data confirm
previous field and greenhouse observations that ‘Dorskamp’ is more tolerant to successive drought and re-watering cycles than
‘Luisa_Avanzo.’ We conclude that this difference is mainly attributable to the plasticity of ‘Dorskamp’ after re-watering,
rather than to clonal differences in drought responses.
Keywords:
duration of leaf expansion, individual leaf growth, predawn leaf water potential, relative leaf water content, soil water
content, stomatal conductance.
