thesis:plant_xylem_intercomp [Hydro-Wiki ]

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Problemstellung

In order to understand from which soil water pool plants take up their water, we need to have a sound understanding of the interactions between water (mobile and tightly bounded) and the soil compartment. Stable water isotopes (²H and ¹⁸O) are a common tool to investigate processes occurring at the soil-plant-atmosphere interface. However, latest studies in soils have shown that the extraction method we apply to gain soil water for isotope analysis is significantly affecting our results. The issues we see with soils and current water extraction techniques remain one of the biggest challenges in achieving this goal. No study has investigated whether different extraction methods not only affect the soil water isotopic signature but also the extracted plant water isotopic composition.

Ziel der Arbeit

Here, we would like to intercompare different lab-based xylem water isotope extraction methods (cryogenic extraction, centrifugation, mechanical squeezing, and the equilibrium technique). The null hypothesis would be that all extraction methods yield the same xylem water isotopic composition independently from the plant species.

Methode

The experiment should be setup in the greenhouse. Different plant species should be selected. Plant physiological parameters should be monitored during the course of the experiment and transpiration rates should be measured. After harvesting different components of the plants, xylem water should be extracted via cryogenic extraction, centrifugation, mechanical squeezing, and the equilibrium technique. Isotope analysis will be conducted at our lab and isotope results should be intercompared between the extraction methods.