Germination response of Erigeron sumatrensis (Retz.) seeds to drying and freezing

Erigeron species form a complex of weed species that have evolved herbicide resistance in Uruguay. Genetic studies using seeds from different biotypes are frequently conducted to understand how this evolution occurred. However, these seeds are extremely small, and there is limited information available on their long-term conservation in germplasm banks. In this context, the aim of this study was to characterize drying strategies for long-term seed storage, comparing prolonged low-temperature drying (20 days at 20 °C, 15% RH) with shorter, higher-temperature drying (10 days at 40 °C or 7 days at 60 °C), and to assess seed germination responses to subsequent freezing (–20 °C for 30 days). The results showed that germination was not affected by any of the drying treatments. Moreover, freezing the seed batches increased germination, particularly in the more recently harvested seed lots (2020 and 2021), and especially when combined with drying at 60 °C. These findings indicate that E. sumatrensis seeds can be classified as orthodox and that long-term conservation in germplasm banks using standard drying and freezing protocols is feasible.