A protocol for the mass-micropropagation of carnation (Dianthus caryophyllus L.)

The influence of increasing the phosphate concentration in Murashige and Skoog medium (MS), ventilation using 500 ml jars covered with rigid, vented polypropylene closures and 1, 2, or 3% (w/v) sucrose on the incidence of hyperhydricity and on shoot proliferation of carnation (Dianthus caryophyllus L.) were examined. Shoot proliferation from nodal explants was induced on MS medium containing 8.87 mu M 6-benzylaminopurine (BAP), whereas shoot elongation and rooting were achieved on MS medium containing 9.8 mu M indole-3-butyric acid (IBA). Hyperhydricity could be controlled, in part, by ventilation, and was completely eliminated by increasing the phosphate concentration of the MS growth medium to 6.45 mM. Moreover, explant growth and morphogenesis were also promoted by increasing the level of phosphate in the MS medium to 6.45 mM. In contrast to MS medium with the standard 1.25 mM phosphate, which produced 7.9 - 10.0 shoots explant(-1), MS medium with an additional 5.20 mM phosphate produced 20.8 - 34.7 shoots explant(-1), depending on providing ventilation and on the sucrose concentration. The water content of shoot clumps, which reflected a decrease in the proportion of hyperhydric shoots, decreased progressively by providing ventilation or by increasing the phosphate concentration. Plantlets were successfully acclimatised and transplanted in a greenhouse. The results suggested that container ventilation and MS medium enriched with 6.45 mM phosphate plus 3% (w/v) sucrose significantly improved the efficiency of mass micropropagation of D. caryophyllus cv. White Sim.