Proceedings Volume 2010 (format .pdf) - SimpBTH

cm and 1.0-1.5 cm, respectively), tall (2.0–2.5 cm and 1.5-2.0 cm, respectively). Theplants were placed into peat : perlite : coco (2:1:1 v/v/v). The percentage of survivingplants was determined after four weeks. The plants were maintained in the growthroom at 24±1 °C and 90% relative humidity. The potted plants were transferred inglasshouse for further acclimatization after six weeks and were planted into gardensoil conditions.Culture conditions: The pH of rooting media was adjusted to 5.6 using 0.1N NaOHor 0.1N HCl before gelling with agar. The media were autoclaved at 121 °C for 20min for sterilization. All cultures were incubated under controlled temperature (22±2°C) and 16 h photoperiod with light intensity of 40 µM m -2 s -1 provided by cool whitefluorescent tubes.RESULTS AND DISCUSSIONSIn vitro rooting of A. montana plants: Induction of rooting is an important stepfor in vitro plant propagation. In our previous study, the multiplication of A. montanawith BAP (1 mg/l) and IAA (0.1 mg/l) yielded normal plants suitable for in vitro rootformation and ex vitro acclimatization stages (Petrova et al., 2005), but these stageswere poorly studied. For in vitro root initiation, the microshoots derived frommultiplication stage were separated and transferred to half strength MS hormone-freemedia or supplemented with three different concentrations (0.5; 1.0 and 2.0 mg/l) ofthe auxins IBA, NAA or IAA (Table 1). Root initiation began after 10-12 days ofculture. Maximum growth of roots occured in the fourth week of culture. The halfstrengthMS medium without auxin showed low root induction and the lowestnumber of roots (1.2) compared to all tested auxins. In contrast, root induction wasobserved when multiple shoots were cultured on media with different concentrationsof auxins. Presence of 2% sucrose in ½ MS with either auxin was found to besuitable for in vitro rooting.1. Effect of Indole Butyric Acid (IBA) on rooting of A. montana: Data presented(Table 1) clearly show the effect of auxin IBA on the in vitro rooting of A. montanaplants. Maximum rooting (100%) was observed on the ½ MS medium supplementedwith all tested concentrations of IBA. The best value of root number per shoot (5.0)was obtained on ½ MS medium with 0.5 mg/l IBA (Table 1, Figure 1a). The meannumber of roots per shoot decreased with increasing IBA concentration. The rootswere greenish, unbranched and normal in appearance. The root lengths ranged from1.5 to 2.4 cm depending on IBA concentration. Of the various auxins supplemented,IBA is more effective in promoting root induction than NAA or IAA. Le (2000)reported induction of adventitious roots on ½ MS medium containing IBA (1.23µM). Butiuc-Keul et al. (2002) obtained highest rooting on basic MS mediumsupplemented with IBA (1 mg/l) and pumpkin extracts (1 ml/l). In contrast,Weremczuk-Jeżyna and Wysokińska (2000) achieved rooting of shoots in MSmedium without the addition of the auxin.260