Estimation of growth parameters in salt-stressed maize: comparison of the pressure-block and applied-tension techniques

A custom-built pressure block was used to estimate the effective turgor (turgor pressure minus the yield threshold) and the cell wall extensibility of the growing zone of the third leaves of 8-d-old maize (Zea mays L.) seedlings. In response to cell wall loosening, pressure in the chamber increased rapidly and reached a maximum after approximately 60 min. Plants treated with 80 mol m^?3 NaCl for 4 h were compared to control plants. Pressure-block analysis revealed that salinity reduced effective turgor, but had no effect on cell wall extensibility. These results are qualitatively and quantitatively similar to those obtained with an applied-tension technique used previously in our laboratory. This study indicates that the pressure-block and applied-tension techniques, which use very different methodologies, estimate similar growth parameters.