Induction of agronomically useful mutants in sorghum through radiations and in vitro techniques

Sorghum is an important millet crop known for its multiple usage as food, fodder and fuel. In this crop, irradiation and cell and tissue culture techniques can be very useful for creating new genetic variation affecting major and polygenic traits. In the present study, two grain sorghum varieties (CO 26, COS 28) and two forage sorghum varieties (CO 27, COFS 29) were utilized. LD50 dose for all the four varieties were fixed (400Gy for CO 26, 350Gy for COS 28, 500Gy for CO 27 and 600Gy for COPS 29. The viable mutants for high yield, high biomass, thick stem, tall and dwarf mutant, stay green, bold grain, grain colour (pearly white in CO 26 and COS 28, red seed colour in CO27), glume colour (red glume in CO27 and COFS 29) and forty five non-shattering mutants (COFS 29) were identified. In grain sorghum, fifty families of CO 26 and forty eight families of COS 28 were selected for high grain yield and in forage sorghum, fifteen families of CO 27 and twenty two families of COFS 29 were selected for high biomass inM4generation. In grain sorghum for stay green trait, twelve families in CO 26 and seven families of COS 28 were selected inM4generation. Agronomically superior mutants are being subjected to further evaluation, selection and stability of performance. In vitro culture studies: The explants utilized for the present study were immature inflorescence and young leaf and the medium used was MS the percentage of callus induction was high (82.14%) in CO 27 leaf explant and percentage of regeneration was high in inflorescence callus of CO 26 and COS 28 (80%). Addition of activated charcoal was found to be effective in reducing the phenols. As regards callus induction, 0.4 g/l activated charcoal was found to be optimum. Double the dose of Fe-EDTA was found to be necessary for high frequency of callus induction and regeneration. The best composition of ingredients for callus induction was 0.4 g/l activated charcoal, 2.0 mg /l 2,4-D and 1.0 mg/l kinetin. The best composition for regeneration was 2.0 mg/l BAP, 0.5 mg/l IAA 1.0 mg/l GA3 and 0.1 mg/l NAA. The first generation of somaclones (SC1 generation) were studied in the glass house. The SC2 generation (second generation) of 182 plants (all the four genotypes) were studied in the field along with M3 generation. Among them, eighty eight families were forwarded to SC3 generation. A high biomass somaclone (36 tillers and 105 leaves) was identified in COFS 29. (author)