Ascophyllum nodosum extract improves leaf thermoregulation by reducing stomatal sensitivity to VPD in Vitis vinifera L.

Sergio Tombesi,Alberto Palliotti,Tommaso Frioni,Paolo Sabbatini,Stefano Poni

doi:10.1007/s10811-020-02336-5

Abstract

Climate change scenarios and the need of sustainable tools to reduce global warming impact on agriculture have led to the formulation of a large number of natural products or biostimulants that should increase plant resilience to abiotic stress. Ascophyllum nodosum (AN) extract is one of the most studied biostimulants to increase tolerance to drought stress, but the physiological mechanism underlying its action is still poorly understood. The aim of the present work was to determine AN extract impact on grapevine gas exchange under well-watered and water stress conditions and to examine its mode of action under stress (light and temperature). AN caused a slight increase in stomatal conductance that resulted in an increase of water plant conductivity to atmosphere. Increased transpiration induced by AN improved leaf thermoregulation, facilitating vine recovery after a stress period. AN increased transpiration through a reduction of stomatal sensitivity to VPD. AN action on stomata regulation indicated that this biostimulant could be a new potential tool to limit leaf damage during events of extreme temperature, even when they are not combined with water stress conditions.

Highlights

Climate change scenarios forecast the increase of mean temperature over the decades along with increased frequency of extreme events such as floods, severe droughts, and hot spells during the summer (IPCC 2013)
Stomatal conductance ranged between 100 and 250 mmol m−2 s−1 under well-watered conditions (Fig. 1a). gs was generally higher in Ascophyllum nodosum (AN) treated grapevine, but it was significant (p < 0.05) only on DOY 183 and 189
At DOY 187, the recovery was partial in WS control treatment (Control) vines and gs values were lower than those of AN vines and WW vines

Summary

Introduction

Climate change scenarios forecast the increase of mean temperature over the decades along with increased frequency of extreme events such as floods, severe droughts, and hot spells during the summer (IPCC 2013). Such climate modifications are a challenge for agriculture; the development of new tools that can reduce the impact of climate extremes on plant productivity has recently gained large attention (Raza et al 2019). AN extract was hypothesized to increase solutes affecting plant osmoregulation capacity during water stress (Khan et al 2009; Di Stasio et al 2018) and to provide precursors that can contribute to the protection of leaf tissues against reactive oxygen species (ROS) formed during stress (Laetitia et al 2010).

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