A METHOD FOR SCREENING RICE PLANTS FOR SALT TOLERANCE

A number of varieties of rice, a halophyte, Sesuvium portulacastrum and a glycophyte, Phaseolus vulgaris were grown in culture solution containing a range of concentrations of NaCl. Growth of the plants and internal sodium concentrations of the roots were measured after 14 days. The electrical potential difference (PD) between the external solution and the vacuole of the outer cells of the root was also measured. This enabled the driving force on sodium at the cell membranes to be calculated using the Nernst equation. It was found that Sesuvium and those varieties of rice that had previously shown salt tolerance generated relatively negative PDs and large driving forces tending to exclude sodium from the root. This suggested that a simple measurement of PD for plants grown in a given concentration of NaCl over a given period of time would provide a fairly rapid screening method for salt tolerance in rice and possibly other species