MUTAGENIC EFFECTIVENESS AND EFFICIENCY OF GAMMA RAYS ON VARIABILITY FOR YIELD ATTRIBUTING TRAITS IN FONIO (DIGITARIA EXILIS [KIPPIST] STAPF.)
A study was conducted to determine the mutagenic effectiveness and efficiency of different doses of gamma rays in inducing variability that could be exploited in the genetic improvement of fonio. Seeds of five accessions of fonio were irradiated with five different doses of gamma rays (100 Gy, 200 Gy, 400 Gy, 500 Gy and 0 Gy as control). The seeds were sown in a plot in a completely randomized design with three replications to rise the M1 generation which was advanced to M2 generation. The result obtained from the M2 mutants revealed highly significant difference (P≤0.01) in the effects of different gamma rays doses on the growth and yield traits of fonio. This implies the presence of high genetic variability induced by the mutagen in fonio. The effect is concentration dependent, increase with decrease in irradiation dose. More so, the effectiveness of the mutagen decreases with increase in dose. Seven different chlorophyll deficient mutants were found in the form of: Albina, Chlorina, Lustescent, Striata, Viridis, Viriscent and Xantha, with Xantha, Chlorina and Albina as the most frequent chimeras, The result indicated that lower dose of gamma rays (100 Gy) is more effective and efficient as it induces favorable mutation that could be utilized in the genetic improvement of fonio. Accession Nkpowas was found to respond more to the mutagenic treatment.