Protocol for the Micropropagation of Tree Peony (Paeonia × lemoinei ‘High Noon’)

An efficient micropropagation protocol was developed for Paeonia × lemoinei ‘High Noon’ using axillary buds as explants. During initiation, 13 propagules were obtained after 50 d of culture with WPM + 0.5 mg/L BA + 0.2 mg/L GA₃. During proliferation, three shoots were obtained after 35 d of culture with WPM1668 mg/L Ca(NO₃)₂·4 H₂O + 0.5 mg/L BA + 0.2 mg/L GA₃, and seven subcultures were carried out. For optimal rooting, the shoots were cultured with 1/2 MS (296 mg/L CaCl₂) + 0.5 g/L activated charcoal for 20 d, then 1/2 MS (296 mg/L CaCl₂) + 1.0 mg/L putrescine + 1.0 mg/L IBA for 30 d for root induction, and finally 1/2 MS (296 mg/L CaCl₂) ＋ 4.0 g/L activated charcoal for 20 d for root development. The rooting percentage of the shoots was 77.2%. During acclimatization, the rooted plantlets were transferred to pots containing a mix of vermiculite/peat/perlite (1:1:1 V/V/V) substrate, and the survival rate was 92.1%. The micropropagation protocol for Paeonia × lemoinei ‘High Noon’ established in this study is valuable for commercial use.