Figure 2. Examination of acclimation conditions for peony plantlets rooted in test tubes. Rooted plantlets (PLKD2, PLNa16-1 and PLNa16-10) acclimated by two different methods (AC1 and AC2) were transplanted into a plant growth chamber at 15°C, or closed greenhouse at 20°C after cold-treatment, and examined for shoot length (A) and number of fresh leaves (B) after two months from transplanting. The values represent the mean±SD (n=16). Asterisks indicate statistically significant differences (Student’s t-test; * p<0.05, ** p<0.01). Photographs show acclimated plants two months after transplantation (C: AC1, D: AC2). The scale bars indicate 5 cm. AC1: Acclimation in a plant growth chamber [15°C constant temperature, 70% relative humidity under 14 h light period (fluorescent light, 190–250 µmol m⁻² s⁻¹)]; AC2: Acclimation in a closed greenhouse (20°C with the same conditions as Table 1) after cold-treatment (4°C) of the rooted plantlets in the test tubes.