Micropropagation technique for mountain laurel (Kalmia latifolia L.) using cytokinin and growth retardant

Abstract : A novel technique for mass propagation and production of miniature pot plants of mountain laurel (Kalmia latifolia) was developed using a tissue culture technique and a plant growth retardant. Juvenile shoot apices that were excised from mother plants in a glasshouse were surface sterilized and used for tissue culture. Woody Plant Medium supplemented with 1 mg/L of N6-(2-isopentenyl) -adenine was adequate for mass propagation of transferable shoots. Shoots taken from flasks were immersed in 100 mg/L indole butylic acid for 3 h to promote rooting and then transplanted to a soil mixture of peatmoss, vermiculite and perlite in a 128-ell tray for acclimatization. Miniature pot plants with a number of flower buds were successfully produced by spraying the transplanted seedlings with 20 mg/L growth retardant (Paclobutrazol) , followed by another spray at 200 mg/L 20 days later. Excessive fertilization suppressed formation of flower buds and enhanced emergence of dwarf leaves. The suppression of plant growth by the Paclobutrazol treatment was recovered by an application of giberrellic acid, indicating that the miniaturization of plants was due to inhibition of gibberrellin biosynthesis in the plants. The micropropagation technique established herein seems to be applicable for that of other woody crops such as tea and paper mulberry