Lethal Dose (LD50) Fixation and Sensitivity of Fenugreek (Trigonella foenum-graecum L.) to Gamma Radiation for Induction of Mutation
Abstract
Fenugreek (Trigonella foenum-graecum L.) is an annual crop, mainly used as a spice and leafy vegetable crop in many parts of the world. Classical breeding in fenugreek is restricted due to its low genetic variability and small flower size which hamper manual emasculation and pollination. Mutation breeding is an effective way to enrich genetic variability in crop plants. An experiment was conducted to determine the lethal dose of the physical mutagen gamma rays in fenugreek. The dry seeds of fenugreek were exposed to different doses of gamma rays i.e. 150 Gy, 200 Gy, 250 Gy, 300 Gy and 350 Gy. These irradiated seeds were sown in the petri plates with non-irradiated seeds (control). As the dose of gamma rays increased, there was a decrease in germination percentage, seedling survival, root length, shoot length and vigour index. Among five doses of gamma rays the maximum seed germination was observed at lowest dose 150 Gy (93%), followed by 200 Gy (83%), 250 Gy (76%), 300 Gy (76%) and 350 Gy (64%). The seedling survival was decreased from 90% (in control) to 56% in 350 Gy dose of gamma rays. The gamma rays dose of 150 Gy gave stimulatory effect on seedlings growth. The growth parameters were dose dependent, as the dose of gamma rays increased from 200 Gy to 350 Gy. The gamma rays dose of 350 Gy showed 64% seeds germination and 56% of seedlings survival. Therefore, it is concluded that the LD50 dose for fenugreek is close to 350 Gy. This information would be highly useful for initiating mutation breeding programme in fenugreek.
