| heal.abstract |
Having as target the increase of shoot production in micropropagation of XMalosorbus florentina Zucc. the effect of thidiazuron (TDZ) on blastogenesis and subsequent microshoot rooting was tested. Nodal explants excised from microshoots, that were grown in vitro on solid MS medium with 1 mg/L BA and 0.1 mg/L IBA, were subcultured on MS media with 0.1, 0.2, 0.5, 1.0 or 2.0 mg/L TDZ, as well as on media with TDZ at the above concentrations combined with IBA at 0.01, 0.02, 0.05, 0.1 or 0.2 mg/L, respectively; the medium with 1 mg/L BA and 0.1 mg/L IBA was used as a control. TDZ induced more microshoots per explant (9.2-10.7 depending on the concentration used), independently of the presence of IBA in the medium, compared to the control (6.6 shoots per explant). Microshoots developed in the presence of TDZ were shorter (0.16-0.35 cm) compared to the control (up to 0.59 cm). The TDZ effect on blastogenesis was limited after two subcultures on MS media with 1 mg/L BA and 0.1 mg/L IBA, or 0.5 mg/L BA and 0.05 mg/L IBA. Microshoots from the second subculture were put on half strength MS medium with 0.5 mg/L IBA and 8 mg/L IAA (one week) for root induction, followed by culture on half strength MS with activated charcoal (one week) and on half strength MS without plant growth regulators (four weeks) for roots' elongation. Microshoots developed in subcultures with 0.5 mg/L BA rooted at higher percentages (11-30%) compared to microshoots developed in 1.0 mg/L BA (4-14%). Similarly, microshoots that were initially developed in media with the lowest TDZ concentration (0.1 mg/L), rooted at higher percentages (30%) compared to microshoots developed initially in higher than 0.1 mg/L TDZ concentrations. |
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