Seasonal and Diurnal Gas-Exchange Characteristics and Water Relations of the Drought Semi-Deciduous Shrub Phlomis-Fruticosa L under Mediterranean Field Conditions
Φόρτωση...
Ημερομηνία
Συγγραφείς
Grammatikopoulos, G.
Kyparissis, A.
Manetas, Y.
Τίτλος Εφημερίδας
Περιοδικό ISSN
Τίτλος τόμου
Εκδότης
Περίληψη
Τύπος
Είδος δημοσίευσης σε συνέδριο
Είδος περιοδικού
peer reviewed
Είδος εκπαιδευτικού υλικού
Όνομα συνεδρίου
Όνομα περιοδικού
Flora
Όνομα βιβλίου
Σειρά βιβλίου
Έκδοση βιβλίου
Συμπληρωματικός/δευτερεύων τίτλος
Περιγραφή
Diurnal and seasonal fluctuations in gas exchange and water relations were examined in the field during a 21 month's period in the drought semi-deciduous shrub Phlomis fruticosa L., in an attempt to reveal environmental factors that may limit its growth and distribution. P. fruticosa is an eastern Mediterranean malacophyllous plant dominating the so called ''phryganic'' ecosystem in Greece (synonym to coastal sage in California and garrigue in France). Maximum photosynthetic rates (c.a. 30 mu mol CO2 m(-2) s(-1)) were observed during the spring, with a secondary maximum at late autumn, a deep minimum during summer and early autumn and a secondary minimum during mid-winter. The deep minimum (c.a. 2-3 mu mol CO2 m(-2) s(-1)) coincided with minimal shoot water potentials and a well-developed stomatal regulation of excessive water loss and CO2 assimilation. Photosynthesis, however,was additionally limited during the dry period by a substantial drop in photosynthetic capacity, as judged by CO2 exchange measurements at saturated (5 %) CO2. The secondary minimum in photosynthesis during mid-winter, occurring at a period of relatively high pre-dawn shoot water potentials and low atmospheric evaporative demand, was partly related to low temperatures in a rather indirect way. Indeed, diurnal changes in shoot water potential revealed a characteristic delay in the replacement of evaporated water at low temperatures, leading to leaf water shortage and stomatal closure, even during the wet period. We may conclude, therefore, that growth in P. fruticosa is restricted by low water potentials during the warm dry period and, possibly, by increased hydraulic resistance when the winter temperatures fall to relatively low values.
Περιγραφή
Λέξεις-κλειδιά
environmental limiting factors, mediterranean climate, phlomis fruticosa, photosynthetic capacity, leaves, sclerophylls, communities, dimorphism, california, greece
Θεματική κατηγορία
Παραπομπή
Σύνδεσμος
<Go to ISI>://A1995QF04800005
Γλώσσα
en
Εκδίδον τμήμα/τομέας
Όνομα επιβλέποντος
Εξεταστική επιτροπή
Γενική Περιγραφή / Σχόλια
Ίδρυμα και Σχολή/Τμήμα του υποβάλλοντος
Πανεπιστήμιο Ιωαννίνων. Σχολή Επιστημών και Τεχνολογιών. Τμήμα Βιολογικών Εφαρμογών και Τεχνολογιών