Morphological, Histological and Genetic Evaluation of Gamma Radiation-Induced Mutation and Its Potential Application in Rudbeckia hirta (L.)

Abstract

Many cultivars of annual ornamental horticulture have great phenotypic qualities but are less tolerant to the effects of current climate change and urbanization. A good example of this in Hungarian ornamental breeding is the Rudbeckia hirta cultivar “Őszifény”. The objective of this study was to determine whether gamma mutation breeding (using 5 Gy, 10 Gy, 30 Gy doses) can be employed to enhance genetic variability and create mutants with novel trait values. Furthermore, it is important to ascertain whether the altered genetic traits are proportionate to the observed changes in phenotype. As an original and innovative aspect of the research, this will assist in establishing appropriate dose rates for the species. Changes induced by gamma radiation have been mapped using morphological, histological, and genetic methods. The radiation dose of 5 Gy resulted in plants with the most favorable characteristics, including significant increases in branching and flower number. Additionally, the phenomenon of hormesis was observed. Beyond these, the dose of 30 Gy also had a significant effect because it resulted in plants with many flowers and bushy habits, making them suitable for use as ornamental potted plants. The 10 Gy dose resulted in a heterogeneous stand but showed the greatest genetic variation. These results may contribute to future breeding work and may pave the way for further urban application of R. hirta in the light of urbanization.