Premium
Different vulnerabilities of Quercus ilex L. to freeze‐ and summer drought‐induced xylem embolism: an ecological interpretation
Author(s) -
GULLO M. A.,
SALLEO S.
Publication year - 1993
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/j.1365-3040.1993.tb00898.x
Subject(s) - xylem , turgor pressure , botany , electrical conduit , irrigation , embolism , biology , hydraulic conductivity , horticulture , environmental science , ecology , soil water , medicine , cardiology , mechanical engineering , engineering
Quercus ilex L. growing in the southern Mediterranean Basin region is exposed to xylem embolism induced by both winter freezing and summer drought. The distribution of the species in Sicily could be explained in terms of the different vulnerability to embolism of its xylem conduits. Naturally occurring climatic conditions were simulated by: (1) maintaining plants for 3h at ambient temperatures of 0, ‐1.5, ‐2.5, ‐5.0 and ‐11°C; and (2) allowing plants to dry out to ratios of their minimum diurnal leaf water potentials (Ψ 1 ) to that at the turgor loss point (Ψ tlp ) of 0.6, 0.9, 1.05, 1.20 and 1.33. The loss of hydraulic conductivity of one‐year‐old twigs reached 40% at ‐1.5°C and at Ψ 1 /Ψ tlP = 1.05. Recovery from these strains was almost complete 24 h after the release of thermal stress or after one irrigation, respectively. More severe stresses reduced recovery consistently. The percentages of xylem conduits embolized following application of the two stresses, were positively related to xylem conduit diameter. The capability of the xylem conduits to recover from stress was positively related to the conduit diameter in plants subjected to summer drought, but not in the plants subjected to winter freezing stress. The ecological significance of the different vulnerabilities to embolism of xylem conduits under naturally occurring climatic conditions is discussed.