ADVENTITIOUS SHOOT FORMATION FROM INVITRO LEAF EXPLANTS OF CARNATION (DIANTHUS-CARYOPHYLLUS L)

A regeneration procedure was developed for carnation (Dianthus caryophyllus L.) using leaves from in vitro grown plants. Leaves were carefully removed from the stem using forceps. Basal explants were incubated on Murashige-Skoog medium with 0.3 mg l-1 benzyladenine (BA) and 0.3 mg l-1 alpha-naphthaleneacetic acid (NAA). After 2 weeks, adventitious shoots developed at the bases of the explants. The position of leaves on the plant appeared to be important, the youngest leaves just below the apical meristem giving the best regeneration results. The regeneration procedure was generally applicable, 24 out of 25 tested cultivars from various carnation types showing regeneration. Using petals as starting material, 37 out of 55 cultivars produced shoots although, as a result of premature flowering, it was usually impossible to transfer regenerated shoots to soil. Regenerants from leaf explants showed no aberrant plant growth. A number of factors were analysed to optimize the procedure. Both BA and NAA in the range 0.1-0.9 mg l-1 affected the average numbers of shoots per regenerating explant, but not the regeneration percentage. The highest number of adventitious shoots was obtained on medium containing 0.9 mg l-1 BA and 0.3 mg l-1 NAA. The two leaves of a leaf pair responded differently, the second leaf to be removed from the stem showing the highest regeneration percentage. Combining the optimum conditions, 65% of the explants showed regeneration with an average of ten shoots per explant.