The effect of short and long-term water deficit on physiological performance and leaf microbiome of different rootstock and scion combinations

Abstract

Climate change, particularly drought stress, threatens viticulture sustainability. Understanding scion-rootstock interactions and their link to the grapevine microbiome is key to improving vine health, productivity, and drought resilience. Our work had two main objectives: 1) to investigate some physiological and morphological characteristics of the Furmint grape variety during short and long-term water deficit and under rewatering 2) to study the effect of short and long-term water deficit on the leaf microbiome of Furmint varieties grafted on different rootstocks.

The pot experiment was conducted in the summer of 2024. Furmint variety was grafted onto Teleki 5C and Richter 110 rootstocks, which have different drought tolerance. Two water deficit treatments were applied for both scion-rootstock combination, 50% and 100% filed capacity, respectively. In addition, drought stressed plants were subjected to a short- (14 days) and a long-term (42 days) water deficit. After both types of water withdrawal, the plants were re-watered. During the experiment, leaf gas-exchange parameters were monitored with a CIRAS-4 portable photosynthesis system, with a particular focus on the pre- and post-rewatering phases. Also, pilot midday- and stem water potential measurements were conducted with Scholander-type pressure chamber. Leaf samples were collected for DNA and RNA extraction from each treatment, enabling microbiome and metatranscriptomic analyses.

Moderate water deficit greatly affected leaf water potential, gas-exchange parameters (A, E, gs), root lengths, root dry matter and individual leaf area. However, the length of the water deficit period significantly affected the gas-exchange parameters of the post-rewatering period. Indeed, during recovery after the 6 weeks from water deficit, stomatal conductance values increased slowly than during the previous rewatering phase. In addition, root growth was significantly affected by water availability and the type of rootstock. In particular, the water deficit has caused the length of the Richter 110 root to increase significantly.

In conclusion, based on the gas-exchange parameters length of water deficit had a significant effect on recovery phase of the plants. Furthermore, we have observed different behaviour of different rootstock-scion combinations under water deficit. Our ongoing microbiome studies aim to characterize the composition and functionality of the grapevine microbiome under drought stress.