ABSTRACT.- Bromus auleticus is a perennial grass native to the campos of South America, valued for its persistence, productivity and forage quality. Conservation and breeding efforts are constrained by limited knowledge of its reproductive aspects. Although allogamy and genetic incompatibility have been reported, these traits have not been sufficiently corroborated across multiple populations. This work aimed to determine the reproductive system of B. auleticus, assess the presence of genetic incompatibility and explore the possibility of obtaining recombinants between contrasting ecotypes. Between 2018 and 2022, seed set and germination of seeds obtained with different pollination methods were compared, pollen-pistil interactions and pollen viability analysis were performed and a hybridization technique was developed. Open pollination treatments showed the highest seed set (48.7%) and germination (56.8%) as well as the highest pollen-pistil compatibility. In self-pollination, the average seed set was 3.13%, germination was intermediate (35.8%) and pollen-pistil interactions were mostly partially compatible or not compatible. These results confirmed that the five accessions show genetic incompatibility, although this mechanism is not strict and requires further study. Inter-accession crosses yielded 1.96% seed set, while intra-accession crosses produced 0.46%. Pollen viability was not a limiting factor in seed formation. This study presents the first report of controlled hybridizations among B. auleticus ecotypes from Uruguay and provides a comprehensive description of the techniques employed. These results have implications for conservation strategies, as well as applications in breeding and seed production, particularly for the selection of crosses with high pollen-stigma compatibility and seed set. © The Author(s), under exclusive licence to Springer Nature B.V. 2025.