Study on Tissue Culture and Rapid Propagation of Different Peony Cultivars
An efficient in vitro propagation system is essential for the rapid multiplication and conservation of peony germplasm resources. In this study, young stem segments, shoot tips, and scale buds of three Paeonia suffruticosa cultivars, ‘Yu Louzi’, ‘Peng Zhouzi’, and ‘Yin Zhihong’, were used as explants to evaluate the effects of surface sterilisation, explant type, and culture medium composition on shoot induction, shoot proliferation, and root induction. Explant contamination decreased progressively with increasing sodium hypochlorite (NaClO) sterilisation intensity, with treatment T4 providing the highest sterilisation efficiency. Among the explant types, contamination rates consistently followed the order scale buds > shoot tips > young stem segments, and the lowest contamination rate (5.1%) was recorded for young stem segments of P. suffruticosa ‘Yin Zhihong’. During primary culture, young stem segments exhibited the highest shoot induction capacity, and MS medium supplemented with 0.5 mg L-1 6-benzyladenine (6-BA) and 0.5 mg L-1 gibberellic acid (GA₃) produced the highest shoot induction rate (89.5%). During shoot proliferation, MS medium supplemented with 2.0 mg L-1 6-BA, 0.1 mg L-1 α-naphthaleneacetic acid (NAA), and 0.1 mg L-1 kinetin (KT) provided the highest proliferation efficiency, with a maximum proliferation coefficient of 4.68. Root primordium induction remained difficult under all treatments. Although 1/2 MS medium supplemented with 1.0 mg L-1 indole-3-butyric acid (IBA) and 0.3 mg L-1 NAA promoted root primordium formation, a stable adventitious root system was not established, and the highest root primordium induction rate was 32.4%. These findings demonstrate that appropriate explant selection and optimisation of culture media can effectively improve shoot induction and proliferation in peony. However, root induction remains the principal constraint to establishing an efficient in vitro propagation system, highlighting the need for further optimisation of rooting conditions.