Research

Physiological ripening disorders of grapevine affect yield and berry quality substantially every year. Although physiological ripening disorders are of high economic importance in viticulture, the information are scarce and causes still need to be identified. Therefore, further attention is needed to understand the induction of the ripening disorder berry shrivel including the influence of environmental factors, which has not been studied so far. The project aims to identify potential underlying environmental factors influencing BS abundance in vineyards in order to develop BS risk factors on a local spatial scale with in multi-disciplinary approach. Thereby we follow the hypothesis that a) environmental factors could summarize to a higher probability of BS incidence, b) that we can scale, translate and extrapolate these factors on GIS maps and c) that wine making itself allows a certain percentage of BS grapes included without negative effects on aroma profiles. Our experimental approach can be summarized in three work packages (WPs): 1) Developing a BS monitoring method and bring this information into a BS abundance map linked with spatial (geology, soil and vineyard management) and temporal (microclimate, climate) information. 2) We are going to investigate the consequences of BS on aroma profiles of berries and processed wines in order to provide recommendations for farmers, and targeted metabolites will be determined on a phenological timescale in order to follow BS development. 3) Finally, we aim to extract BS risk factors on a spatial and temporal scale for vineyards of our study region, and additionally process the obtained information to drought risk maps. Methods used will be: GIS mapping, climate models, soil analyses, geological characterization, vine physiology, targeted metabolites and aroma metabolites. Our approach will close a gap of knowledge on the physiological ripening disorder berry shrivel by establishing the frist time a spatial information of BS within a study region involving a set of important influencing factors relevant for grape berry ripening. This multi-disciplinary approach is a novelty to target berry shrivel with the aim to identify inducing factors.

Optimising water management in vineyards is of great importance for sustainability. As a finite resource, fresh water use for irrigation must be used only when strictly necessary and in the right amounts. Currently, irrigation volumes in vineyards are calculated over the basis of theoretical water consumption estimations performed using only climatic parameters (e.g. calculating fractions of the reference evapotranspiration). Very often the actual plant water status is neglected, mainly because the difficulties of performing reliable measurements in a representative way for a vineyard. Therefore, finding a good proxy for plant water status is pivotal to optimize water management in crops. Artificial intelligence approaches could represent a tool to improve our prediction capabilities. However, artificial intelligence and machine learning approaches require a large amount of data to calibrate the working algorithms. The aim of the project is to provide possible inputs regarding grapevine water use and water status in a digital and continuous way, with proper standard validation measurements, to be use in a machine learning algorithm, with the ultimate goal of training an artificial intelligence able to decide when and how much to irrigate grapevines while optimising the water resources.

Susceptibility of grape berries to stressors such as drought or heat changes according to the stress intensity and duration, but also depending on the berry developmental status at stress occurrence. For example, grapes in the herbaceous phase are more susceptible to drought stress than berries in the ripening stage. Drought and heat stress, which are predicted to increase in frequency and magnitude due to climate change, share a common effect in increasing the production of cytotoxic reactive oxygen species (ROS) in plant cells. While ROS are produced basally as signaling molecules, and plants have adapted mechanisms to detoxify them, stressful conditions increase their production. Given the economic importance of Vitis vinifera for the wine industry in Austria (and worldwide), it is important to understand how ROS metabolism interacts with other metabolic pathways active at the different stages of berry development, and therefore the effects of the timing of ROS-inducing stress factors. The inability to detoxify ROS may cause changes in berry metabolism and development that affect harvest quality, such as by increasing lipid oxidation, membrane damage, and subsequent cell death, the latter of which can cause symptoms such as berry shriveling in extreme cases. The project will explore the different strategies that grape berries could adopt to counteract an increase in ROS molecules produced in response to stressors, including the boost of the antioxidant pool (or de novo biosynthesis of antioxidant molecules) and the modification in the expression of ROS scavenging enzymes. The ROS scavenging capacity of developing grape tissue will be quantified by enzyme activity assays and gene expression analysis. Damage in berries caused by ROS will be quantified following drought and heat imposition in terms of the extent of lipid oxidation, cell death and changes in berry composition.