Phylloxera root infection drives vineyard water

Abstract

Most of the rootstocks used in viticulture today are partly resistant against grape phylloxera (Daktulosphaira vitifoliae Fitch) and host phylloxera on the root system without conspicuous negative impacts on fruit production). Therefore, any decrease in this resistance and/or synergistic interaction with abiotic stresses could exacerbate the impact of phylloxera and have direct consequences on viticulture worldwide. Phylloxera root feeding produces root damage and subsequent gall formation. Root galls affect the whole plant physiology through the impairment of water and nutrient uptake. Recent work demonstrated that phylloxera root feeding modulates plant water use by directly affecting stomatal conductance and transpiration, which may induce a synergistic interaction between phylloxera and drought where premature stomatal closure could have substantial negative impacts on photosynthesis and productivity.

The goal of our work is to understand the biotic x abiotic stress interaction between grape phylloxera and drought and study which of the components of the interaction are synergistic drivers.

The experiment was conducted on the phenotyping platform at the BOKU University in Tulln, Austria. Thirty-two potted 3-year-old vines (Pinot noir | 5BB) were kept under semi-controlled conditions for the full summer season and underwent the treatments: root phylloxeration (by a defined collection of phylloxera root-feeding strains), drought (two subsequent drought cycles with defined recovery phase) and compared to respective non-treated & non-infested control plants in the season 2024. Physiological measurements on water uptake, stomatal regulation and carbon assimilation have been performed on a 2-weekly basis throughout the experiment.

We present first results describing the effects of the single vs. combined stresses as monitored through eco-physiological measurements and grape growth parameters. As one of the main results we show that the water use efficiency (WUE) is affected by the biotic x abiotic stress interaction.