© 2005 Heron Publishing—Victoria, Canada
Osmotic regulation in leaves and roots of olive trees during a water deficit and rewatering
Bartolomeo Dichio (1, 2), Cristos Xiloyannis (1), Adriano Sofo (1) and Giuseppe Montanaro (1)
1. Università degli Studi della Basilicata, Dipartimento di Scienze dei Sistemi Colturali, Forestali e dell’Ambiente, Via dell’Ateneo
Lucano n. 10, Campus Macchia Romana, 85100, Potenza, Italy / 2. Corresponding author (dichio@unibas.it) / Received September 3, 2004; accepted May 15, 2005; published online November 8, 2005
Summary
We evaluated the osmotic adjustment capacity of leaves and roots of young olive (Olea europaea L.) trees during a period of water deficit and subsequent rewatering. The trials were carried out in Basilicata (40°24' N,
16°48' E) on 2-year-old self-rooted olive plants (cv. ‘Coratina’). Plants were subjected to one of four drought treatments.
After 13 days of drought, plants reached mean predawn leaf water potentials of –0.45 ± 0.015 MPa (control), –1.65 ± 0.021
(low stress), –3.25 ± 0.035 (medium stress) and –5.35 ± 0.027 MPa (high stress). Total osmotic adjustment increased with increasing
severity of drought stress. Trees in the high stress treatment showed total osmotic adjustments ranging between 2.4 MPa at
0500 h and 3.8 MPa at 1800 h on the last day of the drought period. Osmotic adjustment allowed the leaves to reach leaf water
potentials of about –7.0 MPa. Active osmotic adjustment at predawn decreased during the rewatering period in both leaves and
roots. Stomatal conductance and net photosynthetic rate declined with increasing drought stress. Osmotic adjustment in olive
trees was associated with active and passive osmotic regulation of drought tolerance, providing an important mechanism for
avoiding water loss.
Keywords:
drought tolerance, gas exchange, Olea europaea, osmotic adjustment, turgor potential, water potential.
