© 2003 Heron Publishing—Victoria, Canada
Osmotic adjustment in three-year-old seedlings of five provenances of maritime pine (Pinus pinaster) in response to drought
Anne Nguyen-Queyrens (1, 2) and Fabien Bouchet-Lannat (1)
1. Laboratoire Ecophysiologie et Nutrition, Institut National de la Recherche Agronomique, Unité de Recherches Forestières de
Bordeaux-Cestas, Domaine de l'Hermitage, Pierroton, F-33611, France / 2. Author to whom correspondence should be addressed (queyrens@pierroton.inra.fr) / Received April 26, 2002; accepted October 19, 2002; published online March 17, 2003
Summary
Three-year-old seedlings of five provenances of Pinus pinaster Ait. that differed in climatic conditions at their geographical origin were subjected to decreasing soil water availability.
The degree of needle osmotic adjustment (OA) was estimated based on logarithmic plots of needle relative water content (RWC)
against needle osmotic potential (Ψπ); i.e., lnRWC versus –ln(–Ψπ). There were significant differences among provenances in active OA (0.13 to 0.30 MPa for a decrease in RWC to 80%), and
a clear negative relationship was found between OA and precipitation (650 to 1280 mm of mean annual rainfall) at the geographical
origins of the provenances. A high osmoregulatory capacity contributes to the maintainance of positive turgor at low water
potentials. We conclude that OA is one of the mechanisms underlying adaptation to drought in P. pinaster. Solute accumulation was about 2.3 times higher in the provenance from the driest site than in the provenance from the wettest
site. The contribution of osmotic adjustment to differences in drought tolerance mechanisms among provenances is discussed.
Keywords:
relative water content, turgor maintenance.
