Homeostasis in leaf water potentials on leeward and windward

IOGNA PI; BUCCI SJ; SCHOLZ FG; GOLDSTEIN G

OECOLOGIA

SPRINGER

Lugar: Berlin; Año: 2013

0029-8549

Phenotypic plasticity in morpho-physiological leaf traits in response to wind was studied in two dominant shrub species of the Patagonian steppe, used as model systems for understanding effects of high wind speed on leaf water relations and hydraulic properties of small woody plants. Morpho-anatomical traits, hydraulic conductance and conductivity and water relations in leaves of wind exposed and protected crown sides were examined during the summer with nearly continuous high winds. Although exposed sides of the crowns were subjected to higher wind speeds and air saturation deficits than the protected sides, leaves throughout the crown had similar minimum leaf water potential (YL). The two species were able to maintain homeostasis in minimum YL using different physiological mechanisms. Berberis microphylla avoided that minimum YL decrease in the exposed side of the crown by reducing water loss by stomatal control, loss cell turgor and low epidermal conductance. Colliguaja integerrima increased leaf water transport efficiency to maintain transpiration rates without increasing the driving force for water loss in the wind exposed crown side. Leaf physiological changes within the crown help to prevent the decrease of minimum YL and thus contribute to the maintenance of homeostasis assuring the hydraulic integrity of the plant under unfavorable conditions. Different from large physiological traits responses, leaf traits that contribute to mechanical resistance (leaf mass per area and thickness) exhibited low phenotypic plasticity. The results of this study help to understand the unique properties of shrubs which have different hydraulic architecture compared to trees.