Germination of Bromus auleticus after different treatments to release seed dormancy

Bromus auleticus is a cool season perennial C3 grass, recognised as a forage plant genetic resource and used for native grasslands restoration. It is native to the campos biome, found in southern Brazil, Uruguay and central Argentina. Its forage yield is comparable with tall fescue. Seed dormancy is a problem to evaluate germination and for commercialisation of this species. Using four recently harvested seed lots of three different genotypes, we tested six different treatments to release dormancy: a control (mean germination 52%); 0.05 and 0.1% gibberellic acid; KNO3; pre-chilling + KNO3; and pre-chilling (mean germination across seed lots and treatments, 87%). Pre-chilling + KNO3 and pre-chilling were the best treatments to break dormancy, with mean germination times (MGT) reduced to half (8.7 and 9.3 days(-1)) that of the untreated control (19.2 days(-1)). The treatment with KNO3 alone did not yield uniform results across seed lots; when combined with pre-chilling, final germination did not increase but showed more consistent results. The use of 0.05% gibberellic acid was less efficient than pre-chilling to reduce the MGT of 17.2 days(-1), but it could be considered as an alternative treatment for seed lots in which the germination results are needed fast and has the additional advantages of avoiding exposing seeds to cold stress. Furthermore, if seeds are contaminated with fungi, it reduces growth time and contamination effects.