Mutation changes in flower colour and plant characteristics of Dendrobium by gamma irradiation

Dendrobium is a popular orchid in commercial markets of Thailand. Release of new improved orchid cultivars remains a challenge in a competitive market. Various mutants of Dendrobium Sonia 'Earsakul' were generated by gamma irradiation. Orchid pseudobulbs (from 20 plants) were acutely (Cs-137) exposed to 0 to 200 Gray (Gy). The LD₅₀ was detected at 50.8 Gy. White area of the flower centers and petals increased 1.83-fold especially after the 30 Gy treatment in the Mutation₁ Vegetation₁ (M₁V₁) plants. An ISSR marker with UBC844 primer clearly showed a different DNA profile during 400-600 bp, comparing with the control (0 Gy). Height of new pseudobulbs of the M₁V₁ plants exposed to 10, 20, and 30 Gy was around 20, 30, 40% less than control after 210 days, respectively. Dendrobium pseudobulbs of M₁V₁ plants treated with 30 Gy generated compact plants and enhanced white area in the flower.