Mutation breeding using gamma rays to increase seed germination in Rosa hybrida.

Breeders are always looking for new and novel varieties to be competitive in the flower market. Low seed germination rate is still a major problem encountered in traditional rose breeding programs. Mutagenic agents, such as ionizing radiation, may be used to enhance seed vigor and increase the productivity, improving sprouting and emergence of buds that are carried out through seed coating. The effects of ionizing radiation on seed vigor are in most cases genotype-dependent, thus irradiation treatments need to be optimised for each different cultivar. In the present study, gamma-rays (0, 50, 100 and 200 Gy) were applied on hybrid tea rose seeds in order to set up a radiation protocol for increasing seed germination. Seeds coming from six different crossings of Rosa hybrida commercial cultivars were used in order to gain information on radiotolerance and germination ability.