Inducing phenotypic variants in sesame (Sesamunindicum L.) with fast neutron irradiation
The mutagenic efficiency and effectiveness of fast neutron irradiation on sesame was evaluated at M1 and M2 generations with the aim of deserning its abiity to induce beneficial mutants with improved agronomic traits that could facilitate selection within local genotypes. Five grames (5g) each of sesame seeds were exposed to four concentrations of sodium azide (0.5mM, 1.0mM, 1.5mM and 2.0mM).Untreated sesame seeds (5g) served as control. The treatments were laid out in a randomized complete block design with three replications. Fast neutron significantly (p<0.05) induced benefitial variabilities on the agronomic traits evaluated. Mutation frequency, mutagenic efficiency and lethalithy induced by fast neutron were not dose dependent. However, the mutagenic effectiveness decreased with increasing dose. Seeds exposed to 0.16sv fast neutron dose showed taller seedling height (15.70cm), reduced days to flowering (45.00), best height at maturity (32.43cm), highest survival rate (35.43%), highest number of leaf per plants (12.50), highest internode length (16.50cm) and best dry weight (12.70g). However, sesame mutants had the best number of seeds per plant (4.60) and thousand seed weight (5.00g) at 0.32sv fast neutron dose. Broad sense heritability estimates for the agronomic traits ranged from 5.96% to 89.73%. Days to flowering recorded the highest heritability value of 89.73%. High heritabilities were also recorded for height at maturity (86.71%) and thousand seed weight (80.00%). Variability in phenotypic characters reflected the existence of genetic diversity among the genotypes.
Keywords: Mutation, Irradiation, Sesame, Heritability, Traits