Table 2. Relationship between cold injury, ice nucleation and freezing temperature in four Eucalyptus globulus genotypes subjected to different drought hardening regimes. Values are means of 5 replicates for the thermal analysis and 8 replicates for the LT50 ± 1 SE. Means with different letters are significantly different (P ≤ 0.05). Lower case letters compare nucleation and freezing temperatures (Columns and rows). Upper case letter compare only within the LT50 column. LT50 = lethal temperature for 50% of leaf cellular damage evaluated by relative conductivity; FS = freezing sensitive, FT = freezing tolerant. |
Genotype |
Hardening |
Nucleation |
Freezing |
LT50 |
Freezing |
EG-13 |
-0.2 |
-7.3 ± 0.2 cd |
-4.6 ± 0.2 efgh |
-7.7 ± 0.2 E |
FS |
-1.8 |
-7.6 ± 0.3 d |
-4.9 ± 0.1 fgh |
-6.3 ± 0.2 BC |
FS |
|
-2.6 |
-5.8 ± 0.2 abc |
-3.0 ± 0.2 e |
-7.0 ± 0.3 CDE |
FT |
|
EG-23 |
-0.2 |
-7.3 ± 0.3 cd |
-5.3 ± 0.4 gh |
-7.6 ± 0.2 E |
FS |
-1.8 |
-7.0 ± 0.3 bcd |
-5.6 ± 0.4 h |
-6.0 ± 0.3 AB |
FS |
|
-2.6 |
-4.8 ± 0.3 a |
-3.1 ± 0.2 e |
-7.0 ± 0.2 CDE |
FT |
|
EG-22 |
-0.2 |
-6.5 ± 0.3 abcd |
-4.6 ± 0.3 efgh |
-6.8 ± 0.0 BCD |
FS |
-1.8 |
-6.8 ± 0.7 bcd |
-5.1 ± 0.5 bgh |
-6.7 ± 0.1 BCD |
FS |
|
-2.6 |
-5.4 ± 0.3 ab |
-3.2 ± 0.6 ef |
-6.7 ± 0.1 BCD |
FT |
|
EG-14 |
-0.2 |
-5.6 ± 0.3 abc |
-3.3 ± 0.3 ef |
-5.2 ± 0.0 A |
FS |
-1.8 |
-5.8 ± 0.3 abc |
-3.9 ± 0.2 efgh |
-7.4 ± 0.1 DE |
FT |
|
-2.6 |
-5.9 ± 0.5 abcd |
-3.6 ± 0.4 efg |
-6.6 ± 0.1 BCD |
FS |
|