Twenty-Four-Hour Induction of Freezing and Drought Tolerance in Plumules of Winter Rye Seedlings by Desiccation Stress at Room Temperature in the Dark

Exposure of seedlings of winter rye (Secale cereale L., cv. Puma) for 2 weeks or 24 hours to desiccation stress (40% relative humidity) at room temperature (21 degrees C) in the dark induced degrees of freezing and drought tolerance in the plumules comparable to those produced by cold conditioning for 2 weeks at 3 degrees C. The induction was associated with repression of growth and could not be produced in plumules excised from the seedlings indicating a requirement for translocation of nutrients from the endosperm. Rapid increase in osmotic pressure, soluble proteins, and phospholipids in plumules in association with the development of freezing and drought tolerance and the requirement of endosperm suggested diversion of nutrient from use in extension growth, to use in augmentation of protoplasm in plumule cells. Since cold acclimation slowed or arrested growth and is associated with augmentation of protoplasm, it is suggested that the common element in the induction of freezing tolerance by cold and drought is the necessity for producing a condition of augmented protoplasm and membranes in cells thus reinforcing a similar conclusion reached from seasonal studies on woody plants.