The Application of Leaf Ultrasonic Resonance to Vitis vinifera L. Suggests the Existence of a Diurnal Osmotic Adjustment Subjected to Photosynthesis

Abstract

The main objective of this study was to apply the air-coupled broad-band ultrasonic spectroscopy in attached transpiring leaves of Vitis vinifera L. to monitor changes in leaf water potential (Ψ) through the measurements of the standardized value of the resonant frequency associated with the maximum transmitance (f/fo). With this purpose, the response of grapevine to a drought stress period was investigated in terms of leaf water status, ultrasounds, gas exchange and sugar accumulation. Two strong correlations were obtained between f/fo and Ψ measured at predawn (pd) and at midday (md) with different slopes. This fact implied the existence of two values of Ψ for a given value of f/fo, which was taken as a sign that the ultrasonic technique was not directly related to the overall Ψ, but only to one of its components: the turgor pressure (P). The difference in Ψ at constant f/fo (δ) was found to be dependent on net CO2 assimilation (A) and might be used as a rough estimator of photosynthetic activity. It was then, the other main component of Ψ, osmotic potential (π), the one that may have lowered the values of md Ψ with respect to pd Ψ by the accumulation of sugars associated to net CO2 assimilation. This phenomenon suggests the existence of a diurnal osmotic adjustment in this species associated to sugars production in well-watered plants.

A low-cost method to rapidly and accurately screen for transpiration efficiency in wheat

“…However, those non-destructive biomass estimates did not result in accurate estimations of TE (Additional file 1 : Figure S4G-H). Doing the measurements early morning before shoot water content drops could improve the results [ 42 , 43 ]. Alternatively, shoot biomass could be estimated via image analysis (e.g.…”

Chl Fluorescence Parameters and Leaf Reflectance Indices Allow Monitoring Changes in the Physiological Status of Quercus ilex L. under Progressive Water Deficit

“…In order to mitigate the consequences of extreme climatic events on forest and agriculture, managers must have a better knowledge of the ecosystem by monitoring plant status [15]. In this sense, the parameter water potential (Ψ) [16,17] is globally used to characterized plant water status (e.g., [18][19][20]). Nevertheless, once water scarcity is over, Ψ can only show managers the recovery of plants in terms of water, leaving unknown the recovery of other physiological processes such as photosynthesis.…”

Surface Density of the Spongy and Palisade Parenchyma Layers of Leaves Extracted From Wideband Ultrasonic Resonance Spectra

“…In this situation, a way to compensate for the decrease in water potential in PP due to water loss would be an equivalent increase in solute accumulation (see Hare et al, 1998), but only in SP. While this solute accumulation has been described in photosynthetically active plants in diurnal (Sancho-Knapik et al, 2016) or seasonal cycles (Callister et al, 2008), under the experimental conditions of our measurements it is very unlikely that the equilibrium between PP and SP is restored in this way. Alternatively, it could be possible that the turgor potential in the PP and SP layers follows a differential evolution so that the equilibrium of water potential between PP and SP is, in this way, kept.…”

“…The larger volume drop in the cells of PP layer than in the SP layer should, in the absence of any other water potential components, produce a flux of water from the SP layer to the PP layer to recover the equilibrium. It is well documented that plant cells can actively change their osmotic potential by accumulating solutes, in the so-called osmotic adjustment (Boyer et al, 2008;Sanders and Arndt, 2012;Sancho-Knapik et al, 2016). In this situation, a way to compensate for the decrease in water potential in PP due to water loss would be an equivalent increase in solute accumulation (see Hare et al, 1998), but only in SP.…”

“…The wide-band, air-coupled ultrasonic resonant spectroscopy method has been presented by Álvarez-Arenas et al (2018). This method is an extension of the air-coupled ultrasonic resonant spectroscopy method presented in Álvarez-Arenas et al (2009); Sancho-Knapik et al (2010, 2013a) that has been widely used for different applications where the determination of leaves water content attracted most of the interest: (Álvarez-Arenas et al, 2016;Sancho-Knapik et al, 2016;Farinas et al, 2019).…”