Physiological, biochemical, and anatomical responses of Araucaria araucana seedlings to controlled water restriction

PAPU; FEDERICO J. BERLI; PICCOLI PATRICIA.; PATON D; ORTEGA RODRIGUEZ; ROIG, FIDEL A.

PLANT PHYSIOLOGY AND BIOCHEMISTRY

ELSEVIER FRANCE-EDITIONS SCIENTIFIQUES MEDICALES ELSEVIER

Lugar: Paris; Año: 2021 vol. 165 p. 47 - 56

0981-9428

Water stress triggers acclimation responses and can damage plants, which varies by species and stress levels.Ongoing climate change is projected to result in longer and more intense water stress conditions leading to analarming increase in drought-induced forest decline. The aim of this study was to evaluate the physiologicalresponses of leaves and stem wood anatomy from Araucaria araucana pot-grown three-year old seedlings, aconifer tree from northwestern Patagonia. Plants were subjected to moderate and severe water restriction re-gimes and compared to well-watered controls. Severe water stress reduced relative leaf water content andtriggered an accumulation of free proline in leaves, regardless of age. Epicuticular wax extrusions increased inapical leaf stomata while photosynthetic pigments decreased, resulting in differential oxidative damage. Theconcentration of phenolic compounds was not affected by water restrictions. Plants exposed to restricted waterregimes showed diminished middle leaf biomass and expansion (~60% of total leaves), increased stem wooddensity, and experienced 7% and 30% mortality rates under moderate and severe water stress, respectively. Ourfindings suggest that under moderate water stress, analogous to short-term droughts, A. araucana seedlingsactivate physiological mechanisms that allow them to withstand short periods of drought, while more severewater stress and longer droughts can be severely harmful