The Professorship's Research

Project start: 01.05.2022
Project end: 30.04.2025
Sponsor: Forschungsring des Deutschen Weinbaus

The aim of the research project is to gain a better understanding of the effect of nitrogen (N) foliar fertilisation in grapevine (Vitis vinifera L. cv. Riesling) on the pattern (quality and quantity) of root exudates. This will also clarify the extent to which the potentially changing exudation pattern influences the composition of microorganisms in the grapevine rhizosphere, which in turn is relevant for the growth of the vine. The latter is due to the fact that there are growth-promoting bacteria in the rhizosphere that are literally "fed" by root exudates. This causal structure is to be investigated as a function of varying amounts of N applied to the leaves.

Project start: 15.01.2022
Project end: 14.03.2025
Sponsor: German Research Foundation

The plant nutrient magnesium (Mg2+) has many functions. For instance, it is relevant for photosynthetic electron transport, for extrusion of protons (H+) by contributing to the activity of the plasma membrane (PM) H+-translocating ATPase, or for sugar partitioning. Under Mg2+-deficiency, mesophyll cells show a reduced operating efficiency of the photosystem (PS) II and accumulate sugars in photosynthetic sources. There is a wealth of information witnessing the relevance of Mg2+ for these processes in the mesophyll tissue. However, current research has not yet achieved to clarify whether the same processes are affected within guard cells (GCs), should these cells contain not enough Mg2+. After all, there is a pressing need to clarify this because evidence is increasing that these Mg2+-dependent processes, i.e. GC-photosynthesis, GC-sugar partitioning, and GC-H+-extrusion are pivotal for regulating stomatal pore size. In GCs at post-dawn, the PM-H+-ATPase energizes stomatal opening upon illumination via hydrolysing ATP for acidifying the apoplast, while GC photosynthesis is a source of this ATP. Disturbed sugar partitioning changes osmotic potential in the GCs with implication on GC swelling. The pressing question is: Is there a link between the amount of Mg2+ in the GCs and light-induced stomatal opening? This research program seeks elucidation if a reduced amount of Mg2+ in GCs of field bean (Vicia faba) obstructs light-induced stomatal opening. As soon as there is not enough Mg2+ in the GCs, it is hypothesized that light-induced stomatal opening is delayed because of a reduced GC PS II operating efficiency (i.e. reduced production of ATP) and a reduced PM-H+-ATPase–mediated extrusion of H+. Moreover, it is anticipated that sugar partitioning is disturbed within GCs that are characterized by a reduced amount of Mg2, which may change GC solute concentration, influencing GC swelling.

Project start: 01.01.2020
Project end: 31.12.2022
Sponsor: German Academic Exchange Service

After a successful partnership of Geisenheim University (HGU) with the University of Thessaly in Greece (ZuGAbe-Project), HGU would now like to establish a partnership with the University of West Attica (UNIWA) and particularly with the Department of Wine, Vine and Beverage Sciences. The cooperation between the two Universities is called Future Challenges in Viticulture, Enology and Wine Business (WOW-project) and is funded by DAAD. The main objective of the project, namely a long-term partnership between the two institutions, will be achieved through common events, such as workshops, conferences, summer schools etc., but also through an exchange program for students and scientists of both universities.