Radiosensitivity of Vetiver to Acute and Chronic Gamma Irradiation

Abstract

Nuclear technology has been widely applied in agriculture for crop improvement. In this study, the radiosensitivities of native Thai vetiver, Chrysopogon zizaninoides, the Kamphaeng Phet 2 and the Surat Thani ecotypes, and Chrysopogon nemoralis, the Ratchaburi ecotype, were investigated with acute and chronic gamma irradiation. Vetiver tillers of the Kamphaeng Phet 2 and the Surat Thani ecotypes were exposed to acute irradiation with gamma radiation from Cs-137 at doses of 0, 10, 20, 30, 40, 50, 60, 80 and 100 Gy. For chronic irradiation with a Co-60 source, the Kamphaeng Phet 2 tillers were exposed to 0, 65, 104, 116, 157, 182 and 205 Gy whereas the Ratchaburi tillers were exposed to 0, 63, 87, 127, 150, 173 and 213 Gy. The survival rate and growth performance measured by plant height, shoot and root dry weight of vetiver at 90 d after irradiation were recorded for median lethal dose (LD50/90) and 50% growth reduction dose (GR50/90) determination. Gamma radiosensitivity differences were observed between the irradiation methods and between the vetiver ecotypes. Acute irradiation caused higher radiosensitivity of vetiver than chronic irradiation. The LD50/90 values of the Kamphaeng Phet 2 ecotype to acute and chronic irradiation were 82 and 100 Gy, respectively. In general, the survival rate and growth of vetiver decreased with an increase in the gamma radiation doses. However, chronic irradiation of the Kamphaeng Phet 2 ecotype at 65 Gy gave higher shoot and root dry weights than the control treatment (0 Gy). The GR50/90 values of the Kamphaeng Phet 2 and the Surat Thani ecotypes to acute irradiation were 48 and 75 Gy for plant height and were 30 and 43 Gy for total dry weight, respectively. For chronic irradiation, the GR50/90 values of the Kamphaeng Phet 2 and the Ratchaburi ecotypes were 118 and 109 Gy for plant height and 121 and 67 Gy for total dry weight, respectively. This information will be useful for radiation-induced mutations in vetiver research.