The Dynamics of Stomatal Closure of Arabidopsis Thaliana Determined by Terahertz Spectroscopy and a Water Transport Model

Terahertz (THz) time-domain spectroscopy allows the detection of temporal changes of plant water content in vivo and non-destructively, for example over the course of the day or at the onset of drought stress. By studying a wildtype and a genetically modified variant of Arabidopsis thaliana, we observed significant differences in their dehydration dynamics. For a better understanding of the underlying processes, we modelled this behaviour with a simple rate equation model, compared the results with the experimental data and correlated our model with the biological regulatory mechanisms. In particular, under drought stress, we found an almost three times ( $$2.80\pm {}0.51$$ ) higher maximal stomatal opening in the mutant than in the wildtype. Over the course of the day, the degree of stomatal opening shows an exponential decrease with a half-life $$t_{1/2}$$ of $$12.3\pm {}$$ 2.6 h in the wildtype and $$3.4\pm {}$$ 0.8 h in the mutant.