Effect of Plant Growth Regulators on In Vitro Plant Regeneration of Purple Amomum Amomum longiligulare T.L. Wu

Purple amomum ( Amomum longiligulare T.L. Wu), which belongs to the monophyletic Zingiberaceae family, is a valuable medicinal plant in Vietnam. The amomum fruit contains essential oils with many valuable chemical compounds, such as camphene, β-pinene, limonene, camphor, borneol, and saponins. In Vietnamese traditional medicine, amomum fruit is used to treat flatulence in pregnant women, diarrhea, indigestion, vomiting, abdominal pain, toothache, and numbness, etc. Besides, it is known as the third most expensive spice in the world after Saffron and Vanilla. An efficient protocol for in vitro regeneration of this important medicinal plant was developed using small pieces of rhizome explants taken from mature plants. Different concentrations of Ca(ClO) 2 (5 and 10%) and HgCl 2 (0.05 and 0.1%) were used to disinfect explants. The explants that were surface disinfected with 0.1% HgCl 2 for 12 min had the highest survival rate, reaching 35.6%. Murashige and Skoog (MS) medium supplemented with 1.0 mg/L 6-benzylaminopurine (BA) or 1.0 mg/L kinetin was the most suitable for shoot initiation stage. In vitro shoots were rapidly multiplication on the MS medium supplemented with 1.5 mg/L BA in combination with 0.25 mg/L naphthaleneacetic acid (NAA), with a multiplier of 5.96 shoots per explant and good shoot quality after 10 weeks of culture. A suitable rooting medium for purple amomum in vitro shoots was MS medium supplemented with 0.5 mg/L NAA or 0.5 mg/L IBA (indole-3-butyric acid), with the mean number of roots was 8.82 and 9.09 roots/shoot, respectively, after 8 weeks of culture. The plantlets were acclimatized and transplanted successfully into “Fasco” bio-soil. The plantlet survival rate was 84.4% after a month and 63.3% after 3 months of transplant.