Improvement in carnation shoot multiplication using thidiazuron in vitro

To improve the plant regeneration efficiency of carnation (Dianthus caryophyllus L.) in vitro, the effect of TDZ on shoot multiplication from somatic tissues was assessed. Adding TDZ to the regeneration medium improved the regeneration efficiency. Of the TDZ concentrations tested, 5 mu M proved to be the optimum for the induction of maximum number (63.6 +/- 0.67) of shoot buds and shoots per explant (46.0 +/- 0.54). However, continuous culture on TDZ containing media induced abnormal bud primodia, which failed to grow into plantlets. For normal shoot development, 10 days limited exposure to TDZ containing media was the optimal treatment. The induced shoot buds were transferred onto the plant growth regulator (PGR) free medium for shoot multiplication and elongation. In vitro rooting in elongated microshoots was obtained on MS medium supplied with 1.0 mu M NAA on which 85-90% of cultured shoots produced healthy roots. The in vitro regenerated plantlets grew well, flowered and attained maturity under greenhouse conditions.