Leaf squeeze-flow rheometry: monitoring plant water status via quasi-static leaf compression

Full description

Turgor is an essential indicator of plant water status; however, turgor measurements are not routine. Turgor can be measured by localised compression of cells or tissues, but an accessible method to perform these measurements is lacking. We hypothesized that leaf turgor pressure can be monitored by uniaxially compressing the leaf lamina and by measuring the stress under a constrained thickness (‘stress relaxation’, SR); and that leaf water content can be monitoring by measuring the thickness of leaves compressed under a constant mechanical stress (‘constant stress’, CS). Using a c. US$300 leaf squeeze-flow rheometer, we showed that uniaxial compression provides accurate measurement of plant water status with high temporal resolution at low cost. Experimental results and a simple hydrostatic equilibrium model indicate that the cell stiffness during compression is determined by the leaf osmotic pressure. Leaf squeeze-flow rheometry is presented as a novel, automatable and potentially standard method to quantify plant water status. Full details are available at Fuenzalida, T.I., Binks, O., Bryant, C.J., Wolfe, J. & Ball, M.C. (2022) Monitoring plant water status via static uniaxial compression of the leaf lamina. Plant, Cell & Environment, 45, 2589– 2606. https://doi.org/10.1111/pce.14383. This study was funded using TIF's personal funds and supported by the Australian Research Council through grant DP180102969: Top-down rehydration: the role of multiple water sources in maintaining hydraulic function of mangroves along gradients in salinity and aridity.

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Significance statement

Development of a semi-automated method to monitor plant water status via uniaxial compression of the leaf lamina.