Comparative effect of high energy electron beam and 137Cs gamma ray on survival, growth and chlorophyll content in curcuma hybrid ‘Laddawan’ and determine proper dose for mutations breeding

Curcuma alismatifolia is an ornamental plant with a beautiful flower in the curcuma genus, which is popular in Thailand and other countries. C. alismatifolia has been improved as the market needs. This research aimed to induce mutations and to study the effects of electron beam and gamma ray on tissue culture of the Curcuma hybrid ‘Laddawan.’ Eight-weeks-old plantlets were irradiated by gamma ray with a Mark I irradiator at the dose rate of 3.74 Gy/min, at the Nuclear Technology Research Center, Kasetsart University. For the electron beam irradiation, samples were exposed to  a high-energy electron beam. The lowest power of this machine is 10 MeV and the lowest radiation dose per cycle is 50 Gy (240 Gy/min). The comparison between the effects of gamma ray and electron beam irradiation at doses of 0, 50, 100 and 200 Gy showed that survival percentage, growth percentage, and chlorophyll content were significantly decreased (P<0.05) when radiation dose increased. The survival percentage, growth percentage and chlorophyll content of gamma-irradiated samples were higher than the electron beam-irradiated samples in the same dose. The results indicated the optimum dose range for gamma irradiation of Curcuma hybrid ‘Laddawan’ in tissue culture is 30 – 60 Gy and for electron beams the dose should be less than 50 Gy.  New characteristics (variegated leaves and light green leaves) were found in M1V2.