Determining the optimum gamma irradiation dose for developing novel maize genotypes

ABSTRACT

Mutation breeding has been used successfully worldwide to generate crop varieties with various traits, including pest resistance. Before any mutation breeding is initiated, radio-sensitivity tests need to be conducted to determine optimum doses for mutagenesis. In this study, radio-sensitivity tests were conducted on three maize (Zea mays L.) genotypes with six gamma irradiation doses. Highly significant effects of mutagenesis on days to seedling emergence, emergence percentage, and seedling height were observed. Regressing seedling height on gamma-ray doses estimated the lethal dose 50 for the three varieties. The study showed that maize seeds were responsive to gamma irradiation and optimal doses can be used to generate novel genetic variability for effective breeding. Doses with high relative biological effectiveness for mutation breeding ranged from 160 gy – 275 gy.

KEYWORDS:

• Gamma irradiation
• maize
• mutagenesis
• radio-sensitivity
• Zea mays

Acknowledgments

We are grateful to the Crop Breeding Institute under the Department of Research and Specialist Services (DR&SS) in the Ministry of Lands, Agriculture, Water, Climate and Rural Resettlement of Zimbabwe and the International Centre for Maize and Wheat Improvement (CIMMYT) for the material support and the Joint FAO/IAEA Division for irradiation of seeds to induce genetic mutations and for their guidance and supervision during the experiment. Germplasm used in this study was developed by CIMMYT, Harvest and DR&SS.

Disclosure statement

The authors declare no conflict of interest.

Additional information

Funding

This work was supported by the IAEA Regional Africa project (RAF5076) on mutation breeding.