Assessment of morphological variations in M4 mutants of IR 841 Rice (Oryza sativa L.) induced by Gamma irradiation

In response to the continuing decline in productivity of rice varieties grown in Togo, the major challenge is to select highly productive varieties adapted to the country's diverse agroecological conditions. This study explored the potential of using gamma-induced mutagenesis of rice to generate genetic diversity. The aim of this work was to characterize the morphological variability of a batch of 50 induced mutant lines of the IR 841 rice variety, indicative of genetic diversity. Fifty 4th generation (M4) mutant lines, along with two controls (non-irradiated variety IR 841 and NERICA L14), were evaluated using 18 IRRI morphological descriptors (5 qualitative and 13 quantitative) in a completely randomized block design with three replications. The results revealed marked phenotypic variability: around 70% of lines showed good panicle exsertion and leaf coloration varying mainly from intermediate to dark green. Significant variations were also observed in quantitative traits such as height, number of tillers and 90% semi-flowering cycle length, which varied significantly for the induced mutant lines studied from 44 to 106 cm, from 18 to 78 tillers and from 68 to 115 days respectively. Multivariate analysis grouped the induced mutant lines studied into four distinct clusters, revealing the existence of significant morphological diversity among the induced mutant lines studied. These results demonstrate the potential of induced mutagenesis to create genetic variability useful for rice breeding in Togo, opening up prospects for the selection of new genotypes adapted to the country's different agroecological conditions.