Optimizing rose micropropagation protocol for mass production.

In recent years in vitro culture has initiated a revolution in propagation of roses. High capacity of production in a short period of time, production of disease free plants and potential of producing in vitro plants all year round and in all parts of the world are the main advantages of tissue culture. In the present investigation optimization of the protocol for micropropagation of one rose species (Rosa persica) and one rose cultivar (R. hybrida cv. Iceberg) was achievedthe accomplished protocol was then optimized for 10 other rose cultivars. Interactive effect of plant growth regulators BAP (0, 2, 4 and 8 ƒفM) and NAA (0, 0.05, 0.25 and 0.5 ƒفM) in VS (Van der Salm) media was used to optimize in vitro propagation of Rosa hybrida cv. Iceberg. Shoot proliferation and number of new leaves were measured as 42 growth indicators. As the concentration of BAP was raised, growth rate was increased with all of the NAA concentrations. However, the highest number of axillary shoots and new leaves were produced with 4 ƒفM BAP, which was considered the optimal level. A multiplication rate of 10 fold with maximum number of axillary shoots (10.1) and new leaves per explant (25) was obtained on the medium containing 4 ƒفM BAP + 0.5 ƒفM NAA. In order to overcome the problem of vitrification in Rosa persica, interactive effect of different levels of sucrose (30, 45 and 60 g/l) and different solidifying agents (agar, phytagel and agar+phytagel) were compared, the results indicated that with all sucrose concentrations, using agar reduced the vitrification to 0%. To reduce yellowing of the in vitro plantlets of Rosa persica, different media were compared. VS medium containing hemicalcium gluconate (2.7 g/l), vitamins from Gamborg&rsquos B5 medium was considered the best. The highest increase in stem length (0.74cm), the highest number of new leaves produced (7.08) and the best quality (1) was observed in this medium. However the highest number of axillary shoots (1.56) were produced on the VS medium containing double amounts of iron. In vitro-derived shoots of Rosa hybrida cv. Iceberg. 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 mm) 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 rate of the rooted plantlets transferred to soil was 70% and 90% in plants treated with semi-sold and liquid media respectively. Rooting and transfer to soil of the other 10 varieties of roses was also successfully carried out and the although the data is not presented for them, percentage of rooting and the survival rate was between 90-100% when sorbarods were used with liquid medium. By using the optimized method, 2000 in vitro plantlets of Rosa hybrida cv Akito were produced and transferred to the greenhouse.