Variation analysis and mutant screening of rice chalkiness by high-energy heavy ion beam radiation

The rice (Oryza sativa L.) varieties Tonghe 66, Suijing 18, Zhongkefa 5 and Jijing 809 were irradiated by high-energy heavy ion beam with doses of 100 Gy, 150 Gy and 180 Gy. The chalkiness rate and chalkiness degree of rice M₂ mutants were measured. Analyzing the variation and screening mutants with different chalkiness rate and chalkiness degree can study the inheritance of rice chalkiness in Japonica rice irradiated by high-energy heavy ion beam radiation, and serve the breeding for appearance quality improvement of rice. The results showed that the chalkiness variation degree of each rice variety M₂ mutants was distinct under different doses. The range of chalkiness rate was 0 − 80.2% and the chalkiness degree was 0 − 44.7%, and the chalkiness tended to low skew distribution. Among the four japonica rice varieties, the chalkiness variation of Suijing 18 M₂ mutants was the most obvious. At the dose of 150 Gy, the maximum variable coefficient of chalkiness rate and chalkiness degree was 191% and 253%, respectively. The higher the dose, the more scattered the chalkiness distribution of Zhongkefa 5 and Jijing 809 M₂ mutants, while Tonghe 66 was the opposite. Among all the M₂ mutants, the high (5.1% − 80.2%) and low (0 − 6.3%) chalkiness rate mutant materials was screened for 127 and 63, respectively. In addition, 133 mutants with high (1.6% − 44.7%) chalkiness degree and 48 mutants with low (0 − 1.8%) were screened. The results provide genetic materials for rice appearance quality improvement breeding.