Dynamics of xylem cavitation during a simulated drought in Eucalyptus camaldulensis saplings, a species with solitary vessels
Recentadvances in plant hydraulics have highlighted the close link betweendrought-induced mortality and resistance to xylem embolism. As theportion of embolized conduits increases, xylem hydraulic conductivitydecreases until water flow stops, inducing plant tissue desiccationand ultimately death. Adaptation to droughtrequires complex interactions between anatomy, physiology andbiochemistry. Thus, long term maintenance of hydraulic integrity iscrucial for survival of tree, including important forestry speciesthat are widely distributed worldwide such as Eucalyptusspecies amongwhich E. camaldulensisis the most spread one, occupying large climatic and environmentalconditions including arid regions. Xylem of thisgenus presents a complex of solitaryvessels surrounded by different imperforate tracheary elements andparenchyma that may influence in a poorly known way their xylemsafety and hydraulic efficiency. We performed this study to unravelthe dynamics of embolism spread in this complex for potted saplingsassigned to a simulated protracted water stress. We relied onstaining and hydraulic methods to test for links between xylemanatomy and the rate of embolism spread in the study plants. Weconcluded that the water stress effectswere not uniform within the complex during the experiment span. Onaverage, the occurrence of embolism wasrandomly distributed. However, this was related to the vesseldiameter of plants poorly embolized i.e. probability of smallestvessels to cavitate was higher than in largest ones. Moreover, thestudy saplings could recover from severe water-stress unless thepercent loss of conductivity (PLC) is up to 77%. There was norecovery when the plants experienced a PLC higher than 85%. ; Fil: Barigah, T. S. Institut National de la Recherche Agronomique; Francia ; Fil: Gyenge, Javier Enrique. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Sur. Estación Experimental Agropecuaria Balcarce; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; Argentina ; Fil: Barreto, F. Instituto Nacional de Tecnología Agropecuaria; Argentina ; Fil: Rozenberg, P. Institut National de la Recherche Agronomique; Francia ; Fil: Fernandez, Maria Elena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Sur. Estación Experimental Agropecuaria Balcarce; Argentina ; International Conference: Adapting forest ecosystems and wood products to biotic and abiotic stress ; San Carlos de Bariloche ; Argentina ; Instituto Nacional de Tecnología Agropecuaria. Estación Experimental Agropecuaria "Dr. Grenville Morris" ; European Union Marie-Curie project TOPWOOD ; Institut National de la Recherche Agronomique
