Resumo

HUGALDE, Inés; BONADA, Marcos  e  VILA, Hernán. The phenomenon of cavitation in grapevine. Unravelling implicated mechanisms. Rev. Fac. Cienc. Agrar., Univ. Nac. Cuyo [online]. 2018, vol.50, n.2, pp.33-47. ISSN 1853-8665.

Cavitation is a physiological dysfunction that takes place in the xylem of water stressed plants. It leads to a loss of hydraulic conductance (k_L) as the vessels are filled with air. This impacts water supply, water potential (Ψ_L) and canopy hydration. Stomatal clossure is an effective response upon diminishing momentary or seasonal foliar hydraulic contents. Depending on each type of plant, stomata may close preventing catastrophic cavitations. This research intended to understand how stomatal control acts upon cavitation events in two contrasting grapevine varieties, Syrah and Grenache. A mechanistic was developed model based on the water and vapour fluxes, k_L, stomata conductance (g_s), and the vulnerability to cavitation of the xylematic tissue. The theoretical model explains how plants respond to drought and avoid catastrophic cavitation. Water stressed grapevines couple their g _s with their k _L in order to avoid embolism. It is not stomatal closure, by istself, the controlling mechanism. Grapevines under mild water stress, do not need to completely close their stomata in order to avoid cavitation, therefore, photosynthesis is not completely impeded, and the cost in terms of carbon assimilation is less than expected for other species.

Palavras-chave : Cavitation; Stomatal conductance; Hydraulic conductance; Mechanistic model; Syrah; Grenache.

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