Assessment of mutagenic sensitivity in blackgram variety CO 6

The present study was conducted to examine the mutagenic effect of 60Co gamma rays and a combination of 60Co gamma rays with EMS in blackgram variety CO 6. Based on the LD50 dose, the seeds were treated with three different doses of gamma rays (200, 300, 400 Gy) and recurrent doses of 20 mM and 30 mM EMS were treated with gamma ray irradiated seeds for combination treatments. The M1 generation was evaluated in the field for the following parameters viz., germination percentage, plant survival percentage, plant height at 30 DAS and maturity, pollen fertility and seed fertility. A dose-dependent decrease was noticed for all the characters under this study in M1 generation. Overall, the maximum reduction was noticed at a higher dose of 400 Gy gamma rays and 400 Gy + 30 mM EMS mutagenic treatments. Among the mutagenic treatments, a combination of 60Co gamma ray + EMS exhibited the maximum effect with a higher percentage of reduction in all the traits while increased pollen sterility was found to be associated with a corresponding increase in dose/concentration of mutagenic agents. A significant positive correlation was observed between viable mutation frequency and biological damage caused by mutagens in M1 generation. Hence, the higher doses of 60Co gamma rays (300 and 400 Gy) and 60Co gamma rays +EMS (300 Gy+ 30; 400 Gy+ 20 and 400 Gy+ 30 mM) proved to be efficient in increasing the mutation frequency towards desirable directions.