Effect of Different Doses of γ-rays (50 Gy, 100 Gy, 150 Gy, 200 Gy& 400 Gy) in M3 Generation of Soybean (Glycine max (L.) Merril) Genotypes

Soybean genetic variation improvement is important for the development of superior cultivars. One of the greatest challenges in mutation breeding is random (uncontrolled) nature of induced mutagenesis. Large population requirement for desired mutant selection brings intensive labor. Choice of appropriate mutagen is one of the deciding factors on succession of the mutation breeding program. Physical, chemical, or biological agents are viable alternatives. Among physical mutagens ionizing radiation sources, particle (electrons, protons, neutrons, alpha and beta particles) or electromagnetic (X-rays, gamma rays), are widely used. Ionizing radiation interacts with genetic material and cause mutations on DNA sequences. Magnitude of mutagenic effect is proportional to the radiation dose Physical mutagen are still improving and mutation breeding proves its value to be fast, flexible, and viable in crop sciences. It is crucial to determine and optimize the effective radiation dose based on experimental plant variety, plant part, and radiation source. 80% of mutation breeding studies prefer physical mutagens and of 60% of this use gamma radiation. In both the soybean varieties, BSS-2 & RKS-18 the spectrum of viable mutation was high at lower dose of Gamma rays. In variety, BSS-2 twining stem, tricotyledon, tetracotyledon were observed while in M3 generation. In RKS-18 stem mutants were not observed. Whereas in the variety, BSS-2, the spectrum of viable mutations was high at dose 100 Gy (14) while in RKS-18, the spectrum of viable mutations was high at lower dose 50 Gy (16).