A protocol for mass production of Rosa hybrida cv. Iceberg through in vitro propagation

Interactive effect of plant growth regulators 6-Benzylaminopurine (BAP) (0, 2, 4 and 8 mM) and 1-Naphtalene acetic acid (NAA) (0, 0.05, 0.25 and 0.5 mM) in Van der Salm (VS) medium was used to optimize in vitro propagation of Rosa hybrida cv. Iceberg. Shoot proliferation and number of new leaves were measured as growth indicators. As the concentration of BAP was raised, growth rate increased with all of the above NAA concentrations. However, the highest number of axillary shoots and new leaves were produced with 4 mM BAP, which was considered the optimal level. A multiplication rate of 10 folds with a maximum number of axillary shoots (10.1) and new leaves per explant (25) were obtained in the medium containing 4 mM BAP plus 0.5 mM NAA. In vitro-derived shoots were used to investigate root initiation and growth by lowering the concentration of VS mineral salts and vitamins. Three strengths of VS (full, 1/2 and 1/4) were compared in semi-solid and liquid medium. The average number of roots (4.35) and root length (0.82 cm) were significantly higher in 1/4 strength VS. The highest percentage of rooting (93.33%) and number of roots (4.45) were significantly higher in semi-solid than liquid medium. The regenerated plantlets were successfully transferred to soil and the survival rates of the rooted plantlets transferred to soil were 70% and 90% in plants treated with semi-sold and liquid media, respectively.