Gamma Irradiation Induced High Yield Mutant Genotype Samosir Local Shallot in the Third Generation

The gamma irradiation can promote the agronomic characters of plant. This study aims to obtain putative mutant genotype of the 3rd generation Samosir local shallot (M1V3), which highly yields. The study used the augmented design in which 8 mutant genotypes of Samosir local shallot from the 2nd generation after gamma (γ)-ray treatment were planted along with untreated. The differences between the irradiation plants and untreated were tested by t-test: Similarity distance and dendrogram were analyzed using the hierarchical cluster. The results showed that almost all the mean values made by all quantitative agronomic character changes in the M1V3 populations were higher than those made in M1V2. The expected high heritability value with a broad coefficient of genetic diversity was found in the character of fresh and dried bulb’s weight resulted from genotype populations treated with γ rays irradiation with doses 3, 4 and 5 Gy. High heritability values were also found in the fresh weight and dry weight of bulb in genotype populations treated with doses 1 and 2 Gy with moderate genetic diversity coefficients. Selection based on the dried bulb’s weight from each mutant genotype population with a selection intensity of 30 % was obtained 39 genotypes that showed the highest selection index. The highest number of genotypes were selected from the application of γ-rays with a dose of 1 to 2 Gy, each of 10 genotypes. Therefore, application at the dose of 1 - 2 Gy in M1V3-generation for Samosir local shallot can still improve the yielding character through breeding to archive shallot in national. HIGHLIGHTS The low doses (1 to 5 Gy) of gamma rays increased the growth and yield of shallots in the third generation The dose at 2 Gy of gamma ray resulted in the highest plant length, number of tillers, number of bulbs, fresh- and dry weight of bulbs in mutant M1V3 of Samosir local shallot The results found that 38 of 39 shallot mutants had greater characters compared to the control The application of 1 - 2 Gy gamma rays on local shallots in the third generation can be used as an effort to increase the yield character GRAPHICAL ABSTRACT