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Response to seasonal drought in three cultivars of Ceratonia siliqua: leaf growth and water relations
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Advisor(s)
Abstract(s)
The responses of leaf growth and leaf water relations to seasonal drought were
monitored, during two successive years, in three cultivars of Ceratonia siliqua L.
growing in the field, in the South of Portugal. In leaves from the current year growth
bulk leaf water relations parameters were characterised using pressure-volume analysis,
and morphometric measurements of xylem in petioles were undertaken. The three
cultivars under study (Galhosa, Espargal and Mulata) differed as to the seasonal pattern
of leaf initiation: in Galhosa a sharp peak of leaf initiation occurred in June, soon before
the period in which the highest leaf expansion rates were determined; on the other two
cultivars (Espargal and Mulata), not only the onset of leaf growth occurred earlier, but
they continued producing new leaves throughout the summer period. The diurnal pattern
of water relations determined in recently-expanded leaves indicated that Galhosa was
the only cultivar in which, during midsummer, leaf water potential was not decreased
below the turgor loss point and leaf relative water content remained above 90%.
Although no conclusive evidence was found for the occurrence of osmotic adjustment in
recently-expanded leaves, during the dry season following leaf formation a seasonal
decrease in osmotic potential sufficient to maintain turgor was detected in the leaves of
Galhosa but not for the other cultivars. As to the anatomy of the xylem at the petioles,
the widest xylem conduits were recorded in Galhosa. This might contribute to explain
why in this cultivar midday leaf water potential never decreased below –2.0 MPa even
at the end of summer drought season.
Description
Keywords
Carob tree Xylem anatomy Water stress Osmotic adjustment
Citation
Correia, Maria João; Coelho, D.; David, Maria Manuela. Response to seasonal drought in three cultivars of Ceratonia siliqua: leaf growth and water relations. Tree Physiology, 21, 10, 645-653, 2001.