Simulating the effect of heat waves on disease-resistant varieties

Abstract

Agro-ecological transition and adaptation to climate change are the two major challenges facing modern agriculture. Viticulture is particularly sensitive to them, given the heavy use of pesticides in vineyards and the need to adapt the grape varieties used to climate change. At the INRAE Grand Est-Colmar center, researchers have successfully implemented the ResDur varietal selection program, which has produced several varieties resistant to both downy mildew (Plasmopara viticola) and powdery mildew (Erysiphe necator), the two main grapevine pathogens. They are are a potent tool to decrease the use of pesticides in vineyards, supporting agroecological transition in viticulture. However, their suitability towards future climate scenarios remains largely unexplored. Another key question is to understand what is the effect of climate change-triggered abiotic stresses on the efficacy of the resistances carried by ResDur varieties. Here, we attempt to study the effect of heat stress on ResDur varieties to answer these questions. As one of the most detrimental consequences of climate change is the increase of intensity and frequency of heat waves, we have developed a device based on infrared (IR) radiators to simulate heat waves with unprecedented accuracy. The principle of the device is to is to generate a fixed temperature difference (∆T) between controls and treated plants throughout a period of several days in semi-controlled conditions, in a way to mimic to increase of temperatures typical of heat waves throughout the day/night cycle. Here, we present the results of the device establishment, which started with the construction and validation of a small-scale prototype in summer 2024. The prototype was built with IP65 IR radiatiors of 1000W connected to a CR1000X Campbell datalog central. Treated and control plants were provided with LAT-B3 leaf temperature sensors that feed the algorithm of the Campbell central, allowing it to pilote the IR radiators in a way to generate a stable ∆T between treated and control plants. This provided a proof-of-concept of the functioning and led to the establishment of bigger scale device to use to perform experiments on ResDur varieties that combine heat and biotic (downy mildew) stress. These experiments are going to take place in spring/summer 2025.