Studies on mutagenic sensitivity of seeds of pummelo (Citrus maxima Merr.)

Mutation breeding is a key method of generating a large number of heritable variations. Effective dose (LD50) needs to be standardized for inducing sufficient variation in a crop. In the present study, seeds were irradiated with different doses of Gamma rays and found that 66.94 Gy could suppress germination close to 50 percent (LD50) in pummelo. This 60 Gy gamma dose can effectively be used for raising the mutant populations to identify a desirable mutation in pummelo.

Study on mutagenic effectiveness and efficiency of mutagens in inducing chlorophyll mutations in m2 generation in sorghum [Sorghum bicolor (L.) Moench ]

An investigation was carried out to create the variability generated through induced mutation in two sorghum populations viz., 296 B (Kharif) and Parbhani Moti (Rabi). Two mutagens viz., gamma irradiation (10 kR, 20kR, 30kR and 40kR) and EMS (0.1%EMS, 0.2%EMS, 0.3%EMS and 0.3%EMS) and their combination were used M2 generation. Mutagenic sensitivity in M2 generation on the basis of reduced germination and plant survival revealed a dose dependent reaction and differential response of the populations. In general, chlorophyll mutation frequency expressed on M2 seedling basis increased linearly with doses of three the mutagens in 296 B and Parbhani Moti. The frequency was more in 296 B followed by Parbhani Moti of three mutagens. The spectrum of chlorophyll mutations comprised albina, xantha, viridis, xanthaviridis, chlorina. The most frequently occurred mutant was viridis type followed by chlorina in all the populations. The population 296 B had expressed largest frequency of chlorophyll mutants followed by Parbhani Moti.

Study on induced mutations in m1 generation in sorghum [Sorghum bicolor (L.) Moench ]

An investigation was carried out to create the variability generated through induced mutation in two sorghum populations viz., 296 B (Kharif) and Parbhani Moti (Rabi). Two mutagens viz., gamma irradiation (10 kR, 20kR, 30kR and 40kR) and EMS (0.1%EMS, 0.2%EMS, 0.3%EMS and 0.3%EMS) and their combination were used M1 generation. Mutagenic sensitivity in M1 generation on the basis of reduced germination and plant survival revealed a dose dependent reaction and differential response of the populations. LD50 was found to be 20-30 kR in case of gamma irradiation and 0.3-0.4 per cent in EMS irrespective of the genotype. The irradiated population produced more number of superior segregants in respects of seed yield and its contributing traits compared to other populations. Three dwarf mutant, one brown midrib and tree drought tolerance confirmed from Parbhani Moti.