Figure 1.
Apricot flower buds cut lengthwise for evaluation after freezing treatment: undamaged by frost (A, B) and damaged by frost (C, D).
Figure 2.
Frost damage of flower buds for 16 apricot cultivars based on artificial freezing tests (October 2019).
Figure 3.
Frost hardiness profiles of 16 apricot cultivars for the dormancy period of 2019/2020.
Figure 4.
Frost hardiness profiles of 16 apricot cultivars for the dormancy period of 2021/2022.
Figure 5.
Frost hardiness profiles of 16 apricot cultivars for the dormancy period of 2022/2023.
Figure 6.
Daily maximum and minimum temperatures during the three dormancy periods (A:2019/20; B:2021/22; C:2022/23) with the frost hardiness profile (LT50 values) of two cultivars: Sweet Red as one of the most frost sensitive and Harlayne as one of the most frost resistant cultivars.
Figure 7.
Results of cluster analysis for frost hardiness based on measured LT50 values for the dormancy periods of 2019/20 (A), 2021/22 (B), 2022/23 (C) and the three years together (D).
Table 1.
Classification of 16 apricot cultivars for their frost hardiness ability by hierarchical clustering with Wards method based on the measured LT50 values.
| Cultivar | 2019/2020 | 2021/2022 | 2022/2023 | 3 years | Legend |
|---|---|---|---|---|---|
| Primaya | G1 | G1 | G1 | G1 | G1—very frost sensitive |
| Tsunami | G1 | G1 | G1 | G1 | |
| Sweet Red | G1 | G1 | G1 | G1 | |
| Aurora | G1 | G2 | G1 | G2 | G2—slightly frost sensitive |
| Pinkcot | G1 | G2 | G1 | G2 | |
| Petra | G1 | G2 | G2 | G2 | |
| Bhart | G2 | G2 | G2 | G3 | G3—slightly frost resistant |
| Goldrich | G2 | G2 | G2 | G3 | |
| Bergarouge | G3 | G2 | G2 | G3 | |
| Magyar kajszi C.235 | G2 | G3 | G3 | G3 | |
| Hargrand | G2 | G3 | G3 | G3 | |
| Farbaly | G2 | G3 | G3 | G3 | |
| Harogem | G3 | G3 | G3 | G3 | |
| Kurezia | G3 | G4 | G4 | G4 | G4—very frost resistant |
| Rózsakajszi C.1406 | G4 | G4 | G4 | G4 | |
| Harlayne | G4 | G4 | G4 | G4 |