Optimal germination conditions for monitoring seed viability in wild populations of fescues

Abstract

Aim of study: Germination assays are vital in the management of material preserved in germplasm banks. The rules published by the International Seed Testing Association (ISTA) are generally those followed in such assays. In wild species, seed dormancy and inter-population variability increase the difficulty in estimating seed viability. The aim of the present work was to determine the germination requirements of the seeds from different wild populations of pasture grasses species. Area of study: Northwestern Spain Material and methods: Seeds from eight wild populations of different species of Festuca, all from northwestern Spain, were studied. Germination assays were performed under constant and alternating temperature conditions. Treatments for removing seed dormancy (cold stratification and gibberellic acid application) were also applied. A full parametric time-to event model was used for data analysis. Main results: In general, the optimum environmental temperature for germination was around 15°C for the populations of Festuca group ovina, F. gr. rubra and F. gigantea; temperatures of 20-30ºC had a negative effect. All the examined populations, except that of tall fescue (Lolium arundinaceum), showed non-deep physiological dormancy at suboptimal germination temperatures, but this was breakable by the application of gibberellic acid and by cold stratification. Research highlights: There are clear inter- and intra-specific differences in germination requirements that might be associated with place of origin. The ISTA germination assay recommendations for wild members of fescues may not be the most appropriate.