Co60 gamma irradiation reduces rooting ability in M1V1 Salvia uliginosa while inducing leaf variegation.

Purpose: Salvia uliginosa is a desirable ornamental shrub for the landscape with blue flowers and the ability to attract pollinators, but limited variation is commercially available in this species. Mutation breeding is a valuable tool to induce variation in ornamental species. However, many deleterious effects are associated with mutation breeding, including reduced rooting ability of vegetative cuttings.

Materials and methods: Cuttings of S. uliginosa were randomly assigned into groups of 10 and exposed to 0, 10, 20, 30, 40, or 50 Gy of gamma rays from a cobalt-60 source to determine an appropriate treatment rate. A follow-up experiment treated 25 S. uliginosa cuttings at 35 Gy to induce favorable mutations.

Results and conclusions: Root quality, survival, and plant height were reduced at higher levels of gamma radiation in the M₁V₁. However, rooting ability was not impacted in M₁V₂ selections. Additionally, one mutant was isolated from the 35 Gy treatment with variegated leaves for a mutation rate of 4%. Our research determined a treatment rate that induced a dominant mutation in S. uliginosa while minimizing the deleterious influence of gamma radiation.