Effect of auxins and cytokinin on micropropagation of Impatiens sirindhorniae Triboun & Suksathan in vitro

Impatiens sirindhorniae Triboun & Suksathan (Balsaminaceae) is an endemic species to Krabi and Suratthani provinces. This study is the first report on in vitro micropropagation of I. sirindhorniae from the reservoir of Ratchaprapa Dam, Khao Sok National Park. The objective of this study was to investigate effect of explants and plant growth regulator treatments on shoot induction. I. sirindhorniae collected from the reservoir of Ratchaprapa Dam were used as explants. The explants were sterilized and cultured on MS agar media supplemented with 0, 0.5 or 1.0 mg L^‑1. BA in combination with 0 or 1.0 mg L^‑1 IBA or NAA for 4 weeks at 25±2°C, under 16-h photoperiod with a light intensity of 60 µmol m^‑2 s^-1. The results showed that all the treatments survived 100%. The highest number of multiple shoots was obtained from the shoot explants cultured on the MS agar medium supplemented with 0.5 mg L^‑1 BA and 1.0 mg L^‑1 IBA (2.22 shoots explant^‑1). However, the longest shoot was obtained from the shoot explants cultured on MS medium without plant growth regulator (1.48 cm).