Saline Growth Conditions Favour Supercooling and Increase the Freezing Tolerance of Leaves of Barley and Wheat

Abstract

When young plants of barley and wheat grown in hydroponic culture were subjected to salt stress, their freezing tolerance increased with increasing severity of salt stress. Detached leaves from salt-stressed plants also exhibited an increased ability to supercool. Avoidance of ice formation permitted leaf survival at subzero temperatures which were no longer tolerated when ice nucleation resulted in extracellular freezing. The increased freezing tolerance under salt stress is attributed to osmotic adjustment of the plants. Increased cellular solute concentrations decrease the extent of cellular dehydration at freezing temperatures, thereby decreasing mechanical and chemical stresses on biomembranes during freezing and thawing.