Professor Jordi Voltas Velasco, Professor Juan Pedro Ferrio  - Department of Crop and Forest Sciences, University of Lleida

LLEIDA, SPAIN — Our lab performs isotopic water analysis with a Picarro L2120-i analyzer. Our principal application using the Picarro analyzer is the isotopic analysis of xylem water to identify variations in water source during its uptake from the soil. This is based on the fact that there is an evaporation gradient in the soil and as a result, water obtained from distinct depths has a distinct isotopic signal. We are using this principle in distinct contexts to resolve various questions. First we are analyzing xylem water as a provenance test for intra-specific genetic variation in crops and trees such as Pinus halepensis Mill. In such a provenance test, a tree plantation is established using seed of distinct origin (in our case from throughout the Mediterranean basin). The objective is to determine if adaptive genetic differences exist, according to provenance, regarding the capacity of the trees to extract deep soil water. 

We are also applying the same principle to compare varieties of wheat and maize.  In this latter case, due to the difficulty in conserving samples for cryogenic distillation, we are doing tests in which we directly analyze the “juice” squeezed from the stem. In this aspect the Picarro analyzer has an advantage over IRMS since it analyses just the water, and not the sugars. Therefore one can expect that the isotopic signal is similar to that of the xylem water.  We are hoping to acquire Picarro's Induction Module to combine with our L2120-i isotopic water analyzer to perform the water extraction.

A further line of our research is Seasonal Variation and Competition. In this case, we are making ongoing measurements throughout all seasons in a parcel of land where there coexist two typically Mediterranean species, Pinus halepensis Mill. and Quercus ilex L. Both species are well adapted to drought conditions but with differing strategies. Our objective here is to analyze the spatial variability in water extraction and observe how these two species interact with each other. The starting hypothesis is that the trees behave in a different manner according to whether their neighbours are of one species or the other. Our group also provides external isotopic analysis services for provenance studies and other isotopic water applications and we enjoy the flexibility and high throughput that the Picarro analyzer has given us in this regard.

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