Development of genetically diverse breeding lines through induced mutagenesis for the improvement of Chinigura and Kataribhog aromatic rice (Oryza sativa L.) landraces.

PURPOSE: In Bangladesh, Chinigura and Kataribhog stand out as two of the most popular short-grained aromatic rice cultivars, particularly in the northern regions. Their unique grain characteristics and delightful fragrance make them highly sought after. However, these cultivars suffer from low yield potential (<2.5 t/ha) and are prone to lodging due to their tall plant height (>140 cm). The narrow genetic base and hybrid sterility issues with non-scented rice varieties make improving these cultivars through traditional breeding methods challenging. We applied induced mutation to these cultivars to address these challenges and enhance the yield potential and lodging tolerance.

MATERIALS AND

METHODS

To induce mutations, we exposed Chinigura and Kataribhog dry seeds with a moisture content of 12% to gamma rays at five doses: 100, 200, 250, 300, and 400 Gy. We conducted the process in a controlled environment with strict safety measures to ensure our safety and that of the environment. Putative mutants with shorter plant height and growth duration were isolated from the segregating M2 population, and then the putative mutants were validated in the M3 and M4 generations. Finally, we conducted a replicated yield trial with 21 selected mutants.

RESULTS

Our study revealed that the Kataribhog cultivar was more responsive to gamma irradiation than Chinigura. The 250 Gy irradiated Kataribhog population exhibited the highest mutation frequency. We validated the mutants selected from the M2 population based on plant height and growth duration in the M3 and M4 generations. Ten mutants from Chinigura and 11 from the Kataribhog population, selected from the M4 generation, were advanced to the replicated trial. These mutants exhibited semi-dwarfism, lodging resistance, higher grain yield, and aromatic properties. Ultimately, we successfully identified 12 semi-dwarf lodging resistant, seven with higher grain yield, and three aromatic mutants for the subsequent breeding programs, demonstrating the effectiveness of induced mutation in creating desired traits.

CONCLUSION

First, the report will discuss the development of semi-dwarf mutants in Chinigura and Kataribhog aromatic rice cultivars through gamma irradiation.