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Medientyp:
E-Artikel
Titel:
Drought tolerance in faster‐ and slower‐growing black spruce (Picea mariana) progenies: I. Stomatal and gas exchange responses to osmotic stress
Beteiligte:
Tan, Weixing;
Blake, Terence J.;
Boyle, Timothy J. B.
Erschienen:
Wiley, 1992
Erschienen in:
Physiologia Plantarum, 85 (1992) 4, Seite 639-644
Beschreibung:
<jats:p>Sixteen years growth in height and basal stem diameter of full‐sib black spruce [<jats:italic>Picea mariana</jats:italic> (Mill.) B. S. P.] progenies varied with soil moisture availability. The responses to water stress of two faster‐growing progenies under drought were compared with two slower‐growing progenies to determine the physiological basis of drought tolerance. Six‐month‐old seedlings were stressed using an osmoticum, polyethylene glycol‐3350 (PEG). Seedlings were passed through a series of increasing concentration: 10, 18 and 25% PEG (w/v) each for 3 days to provide solution water potentials of ‐0.4, ‐1.0, and ‐2.0 MPa, respectively. The stress was then relieved by returning the seedlings to nutrient solution without PEG for 24 hours. Gas exchange and water relation parameters were similar in the 4 progenies prior to the imposition of the stress but varied during the stress and after stress relief. The two progenies which grew more vigorously on the driest site maintained significantly higher stomatal conductance, leaf transpiration rate, and net photosynthesis rate during mild (10% PEG) and moderate (18% PEG), but not severe (25% PEG) osmotic stress, and also recovered faster after release of the stress than the other two slower‐growing progenies. Black spruce progenies did not differ in xylem water potential or water use efficiency. Progenies capable of faster growth under drought stress were thus characterized by a greater dehydration tolerance, rather than postponement, compared with slower‐growing progenies.</jats:p>