Evaluation of the Saline–Alkaline Tolerance of Rice (Oryza sativa L.) Mutants Induced by Heavy-Ion Beam Mutagenesis

SIMPLE SUMMARY: Soil salinization is one of the important obstacles restricting agricultural development. Cultivating new varieties of saline–alkaline-tolerant rice can increase the yield of rice. It is possible to minimize breeding costs and shorten the breeding period through heavy ion beam irradiation mutation breeding. Our research evaluated and screened saline–alkaline-tolerant rice mutants induced by heavy ion beams. The results show that heavy ion beam radiation is an effective method for breeding new saline–alkaline-tolerant rice cultivars, and the selected mutant lines have excellent production performance under saline–alkaline stress. Our research results provide new theoretical and practical insights that can be used to help develop new saline–alkaline-tolerant rice cultivars. ABSTRACT: Soil salinity is a widespread and important abiotic factor impeding rice production by adversely affecting seed germination, seedling growth, and plant productivity. In this study, the rice cultivar TH899 was treated with 200 Gy of heavy-ion beam irradiation, and 89 mutant lines with stable phenotypes were selected using the pedigree method based on continuous assessment over six years. The seed germination performance of these mutants was tested under different saline–alkaline concentrations. Five highly tolerant lines were further evaluated in a series of experiments at the seedling stage and in the field. During the seedling stage, the reduction of seedling length, root length, fresh weight, and dry weight were dramatically lower in these five mutants than those in TH899 under saline–alkali stress. The K(+)/Na(+) ratio was higher in these five mutants than in TH899. In the field experiment, the grain yield of mutant lines was higher than that of TH899. In addition, the grain yield of mutant line M89 was higher than that of the local cultivar in actual production. These mutant lines are expected to increase grain yield in soda saline–alkaline regions in northeast China.