Shoot initiation and multiple shoot induction of Sangmon 'Nuan Rajinee' bamboo (Dendrocalamus sericeus Munro)

Effects of plant growth regulators on shoot initiation from a node segment and multiple shoot induction from a shoot clump of Sangmon 'Nuan Rajinee' bamboo (Dendrocalamus sericeus Munro) were investigated. A surface-sterilized nodal segment was cultured for 3 weeks on Murashige and Skoog (MS) medium supplemented 6-benzyl adenine (BA) at different concentrations (8.88-22.20 µM). The results showed that MS medium added with 17.76 µM BA provided the highest average number of shoots (2.5 shoots) from a node with the average shoot length at 10.52 mm. For multiple shoot induction, a clump of shoot (about 3-5 shoots clump^‑1), initiated from a node, was cultured for 3 weeks on modified MS medium supplemented with BA (1.11 or 2.22 µM) or thidiazuron (TDZ) (0.45-1.36 µM) or brassinolide (BL) (0.001-10.0 µM). The medium containing TDZ at the concentrations of 0.45 and 0.90 µM gave the best survival rate (100%) and the highest number of shoots increased at 10.8 and 9.0 shoots (3.6-fold and 3.0-fold increase) with average shoot length 20.33 and 14.94 mm, respectively. However, BA (1.11 µM) in combinations with TDZ (0.45-1.36 µM) or with BL (0.001-10.0 µM) in modified MS medium was used for multiple shoot induction from a 1-2 shoot clump. It was found that medium added with 1.11 µM BA in combination with 0.45 µM TDZ provided 100% survival and the highest number of shoots increased at 2.4 shoots (2.8-fold increase) with 34.32 mm shoot long. For BL added in medium containing 1.11 µM BA, the low concentration of BL (0.001 and 0.1 µM) showed better results than the high concentration (10.0 µM), however, number of shoots increased was not found.