Cell Wall Elasticity as a Mechanism to Maintain Favorable Water Relations During Leaf Ontogeny in Grapevines

¹ Laboratory of Viticulture, Aristotle University of Thessaloniki, P.O. Box 236 - 54006 Thessaloniki, Greece.
² Dept. of Range and Wildlife Sciences, Aristotle University of Thessaloniki, P.O. Box 236 - 54006 Thessaloniki, Greece.

The aim of this study was to elucidate the influence of leaf age on water relations parameters and cell wall elasticity which is considered to be one of the most important physiological mechanism of adaptation to water stress. The relationships between the water, turgor, osmotic potentials and leaf water content were studied in both mature and immature leaves of field grown grapevines (V. vinifera L.) using the pressure volume technique. The symplastic water fraction of the total water content averaged 0.78 and 0.69 for immature and mature leaves respectively. The calculated volumetric modulus of elasticity was significantly lower in immature leaves contributing in turgor maintenance and plant growth under mild water stress conditions. The reduction in cell wall elasticity observed in mature leaves, which resulted in rapid changes of in response to small water losses, may confer an efficient physiological mechanism to face short-term water stress conditions as well as to favor production under drought conditions.

Key words: Immature leaves, leaf ontogeny, mature leaves, Vitis vinifera, water relations

Submitted on July 9, 1996