Table I.

Freezing characteristics of winter rye leaves from plants grown at 20°C (NA) or 5°C (CA), or grown at 20°C and treated with ABA or ethephon as described in “Materials and Methods”

Freezing and supercooling temperatures were determined by IRVT in the presence and absence, respectively, of ice+ bacteria. LT50 was calculated as the temperature at which the leaf lost 50% of the total leaf conductivity following freezing and thawing. Data are presented as means ± se (number of replicates). Within a row, means followed by different letters are statistically different from each other at P ≤ 0.05. Antifreeze activity was determined by observing the shape of ice crystals grown in solution. NA, Nonacclimated; CA, cold acclimated; FW, fresh weight.

CharacteristicTreatment of Winter Rye Plants
NAABAEthephonCA
Apoplastic protein content (mg g−1 FW)0.1 ± 0.03 (3) aab0.4 ± 0.01 (3) ba0.3 ± 0.02 (3) bc0.3 ± 0.01 (3) bb
Freezing temperature (°C)−2.4 ± 0.1 (16) a−2.1 ± 0.1 (17) a−2.7 ± 0.2 (19) b−3.3 ± 0.2 (16) b
Supercooling temperature (°C)−13.4 ± 0.3 (3) a−13.8 ± 1.0 (3) a−13.6 ± 0.5 (3) a−12.2 ± 2.8 (3) a
LT50 (°C)−7.0 ± 0.1 (3) a−7.3 ± 0.1 (3) a−6.3 ± 0.3 (3) a−25.3 ± 0.7 (3) b
Antifreeze activityNoNoYesYes
  • a Data from Yu and Griffith (2001).

  • b Data from Marentes et al. (1993).

  • c Data from Yu et al. (2001).