| Summary: | The present study was conducted to determine the mutagenic effectiveness, efficiency and lethal dose of gamma rays
in papaya varieties CO7, Arka Prabhath and Arka Surya. Papaya seeds were exposed to various doses of gamma
rays (0Gy, 100Gy, 150Gy, 200Gy, 250Gy, 300Gy, 350Gy, 400Gy, 450Gy and 500Gy) and the mutagenic effectiveness
and efficiency of gamma rays were assessed based on the chlorophyll mutation frequency and biological damage
in M1 plant basis. There was a negative relationship between mutagenic effectiveness and efficiency with the doses
of gamma irradiation. LD50 value was optimized in CO7, Arka Prabhath and Arka Surya as 354, 348 and 341Gy
respectively. Generally, the germination, survival and growth rate of papaya decreased with an increase in gammairradiation
doses. Lower doses of mutations created very few mutations and higher doses of gamma irradiation induced
lethality and sterility of seedlings whereas, lethal dose 50 has proved to be more effective in inducing desirable
mutations in papaya. Since identifying the mutagenic efficiency and effectiveness of the mutagen and optimization of
lethal dose is the preliminary step in any mutagenic experiment, this study will offer a foundation for further gamma
irradiation studies in papaya to develop desirable mutants.
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