Plant regeneration system was developed through shoot organogenesis from in vitro leaf explants of Chrysanthemum morifolium 'Oblang'. The effects of concentrations of plant growth regulators and AgNO3 for efficient shoot regeneration and inhibition of browning were evaluated in chrysanthemum. The explants were cultured on shoot induction medium, MS medium supplemented with 12 combination treatments of BA (0.5, 1.0, 2.0 mg/L) and NAA (0.2, 0.5, 1.0, 2.0 mg/L), in darkness for 6 weeks and cultured under the 16/8h photoperiod for 6 weeks. The highest shoot regeneration was obtained from the explants cultured on the medium with 1.0 mg/L BA and 1.0 mg/L NAA. Based on this result, AgNO3 was added to a shoot induction medium containing MS salts, vitamins, BA 1.0 mg/L, NAA 1.0 mg/L, sucrose 30 g/L, and agar 6 g/L to reduce browning of chrysanthemum leaf explants. In control treatment, without AgNO3, leaf explants turned brown in the cut edge. However, the browning were not observed in AgNO3 treatments. The shoot organogenesis was good at low concentration of AgNO3 and decreased with the increase of AgNO3 concentration. The explants cultured on shoot induction medium (MS salts, vitamins, 1.0 mg/L BA, 1.0 mg/L NAA), with 1 mg/L of AgNO3 produced the highest shoot regeneration with 2.6 shoots per explants and browning index of 0.7. When the regenerated shoots were detached from the explants and cultured on MS medium, the shoots were elongated and rooted successfully.

Keywords: Chrysanthemum, ‘Oblang’, Shoot organogenesis, Plant regeneration, Silver nitrate