The olive tree: a paradigm for drought tolerance in Mediterranean climates A. Sofo1, S. Manfreda2, M. Fiorentino2, B. Dichio1, and C. Xiloyannis1 1Dipartimento di Scienze dei Sistemi Colturali, Forestali e dell'Ambiente, Università degli Studi della Basilicata, Via dell'Ateneo Lucano, 10, 85100 Potenza, Italy 2Dipartimento di Ingegneria e Fisica dell'Ambiente, Università degli Studi della Basilicata, Via dell'Ateneo Lucano, 10, 85100 Potenza, Italy
Abstract. Olive trees (Olea europaea L.) are commonly grown in the Mediterranean basin where
prolonged droughts may occur during the vegetative period. This species has developed a series of
physiological mechanisms, that can be observed in several plants of the
Mediterranean macchia, to tolerate drought stress and grow under adverse climatic conditions.
These mechanisms have been investigated through an experimental campaign carried
out over both irrigated and drought-stressed plants in order to comprehend the
plant response under stressed conditions and its ability to recover.
Experimental results show
that olive plants subjected to water deficit lower the water content and
water potentials of their tissues, establishing a particularly high
potential gradient between leaves and roots, and stop canopy growth but not
photosynthetic activity and transpiration. This allows the continuous
production of assimilates as well as their accumulation in the various plant
parts, so creating a higher root/leaf ratio if compared to well-watered
plants. Active and passive osmotic adjustment due to the accumulation of
carbohydrates (in particular mannitol and glucose), proline and other
osmolytes have key roles in maintaining cell turgor and leaf activities. At
severe drought-stress levels, the non-stomatal component of photosynthesis
is inhibited and a light-dependent inactivation of the photosystem II
occurs. Finally, the activities of some antioxidant enzymes involved in the
scavenging of activated oxygen species and in other biochemical pathways
increase during a period of drought. The present paper provides an overview
of the driving mechanisms adopted by olive trees to face drought stress with
the aim of better understanding plant-soil interactions.
Citation: Sofo, A., Manfreda, S., Fiorentino, M., Dichio, B., and Xiloyannis, C.: The olive tree: a paradigm for drought tolerance in Mediterranean climates, Hydrol. Earth Syst. Sci., 12, 293-301, doi:10.5194/hess-12-293-2008, 2008.