Aim: The aim of this study is to compare potentials for the in vitro regeneration of apical and nodal explants of New Guinea Impatiens in the presence of cytokinins. It is also to develop a simple, fast, cost-effective and efficient protocol for micropropagation of this valuable plant species, which is one of the most important and popular pot and bedding plants in the world. Methodology: Due to the high contamination rate of Impatiens explants in in vitro conditions, a preliminary experiment on surface sterilization of the bud explants using various sterilization reagents, including sodium hypochlorite, mercuric chloride, and Cefotaxime was performed. In addition, the effects of various concentrations of Benzyl Amino Purine (BAP) and Kinetin (KIN) on proliferation of apical and axillary bud explants were investigated. Following two subcultures in multiplication media, the plantlets with well-developed roots were directly transferred to plastic cups and later to the greenhouse for acclimatization. Results: The most effective sterilization procedure, which resulted in 75 percent healthy explants, was recognized when the bud explants were disinfected with 0.1 percent mercuric chloride – 6 minutes – followed by a culture on Murashig and Skoog medium, consisting of 300 mg/l Cefotaxime. Also, between the two types of buds studied here, our results showed that axillary buds were more efficient in inducing higher adventitious shoot regeneration compared to that for apical buds when they were exposed to 0.5 mg/l BAP in MS medium. In addition, we observed that the in vitro roots were simultaneously induced during shoot proliferation and maximum generated root number was observed in the medium containing 1mg/l BAP). Our results showed that about 95 percent of the regenerated plantlets survived, acclimatized successfully, and continued their normal and vigorous growth in the greenhouse. Interpretation: Findings of the present work indicated that the use of axillary buds in the presence of low concentrations of BAP were effective in multiplication of New Guinea Impatiens. The simultaneous occurrence of rooting during proliferation was beneficial in significantly reducing the time and costs of micropropagation procedure. Based on our results, we proposed a simple, fast, efficient, and economic protocol that can be easily commercialized for micropropagation of Impatiens hawkeri ‘Cherry Red’.

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