Drought effects on hydraulic conductivity and xylem vulnerability to embolism in diverse species and provenances of Mediterranean cedars.

摘要: We studied hydraulic traits of young plants the Mediterranean cedar species Cedrus atlantica (Endl.) G. Manetti ex Carriere (Luberon, France), C. brevifolia (Hook. f.) Henry (Cyprus), libani A. Rich (Hadeth El Jebbe, Lebanon) and (Armut Alani, Turkey). With an optimum water supply, no major differences were observed among or provenances in either stem conductivity (K s ) leaf specific l measured on main shoot. A moderate soil drought applied for 10 weeks induced marked acclimation through a reduction K , particularly Lebanese provenance libani, decrease tracheid lumen size all species. atlantica, which had smallest tracheids, was most vulnerable to embolism: 50% loss (Ψ PLC50 occurred at potential -4.4 MPa well-watered treatment, -6.0 treatment. In other species, Ψ unaffected by drought, only declined sharply potentials between -6.4 -7.5 both irrigation treatments. During severe twigs stomatal conductance (g simultaneously as declined. For lower vulnerability embolism based recorded current-year twigs. The threshold closure (10% maximum g reached predawn pd -2.5 (Luberon) -3.1 (Lebanon), whereas intermediate values. brevifolia, with (-3.0 MPa) close that highest study importance margin safety causing xylem induction is discussed.