SEED LONGEVITY IN STORAGE OF ALPINE PLANT SPECIES

Seed longevity has been investigated predominantly in relation to taxonomic and macroclimatic differences, while little is known about the variation within closely related taxa, growing under the same climate. Therefore, seed longevity of 18 alpine species Asteraceae was compared using artificial ageing (AA) to ascertain the influence of seed and species-specific ecological traits (i.e. seed mass, soil pH and moisture) on seed longevity. The estimates of p50 (estimate the time for viability to fall to 50 %) ranged between 1.63 and 40.03 d. Soil moisture significantly influenced seed longevity, with seeds of species growing on dry soil showing higher p50 than those from wetter soil. Conversely, seed mass and soil pH did not significantly contribute to longevity differences across species, though species from acid soils tend to be shorter lived than those from basic soils. Plant ecological traits, linked to condition at the plant growing site may play crucial roles in the prediction of seed lot longevity in air-dry storage including seed bank conditions. Germination test by means of radicle protrusion is often used as an assessment of seed viability (i.e. seed longevity studies). Therefore, there is a possibility that radicle protrusion alone may over-estimate viability compared with normal germination (i.e. radicle plus cotyledon emergence), thereby seed longevity. However, the extent of such overestimation across species and the factors contributing to it are not yet well understood. Therefore, seed life span of 35 alpine species was studied by evaluating both radicle emergence and normal germination during artificial ageing (AA). Estimates of p50 based on radicle emergence (p50 (RE)) were significantly higher than estimates based on normal germination (p50 (NG)) in 18 (51.4 %) out of the 35 species tested, suggesting radicle emergence may not be a reliable indicator of the capacity of seeds to complete the germination process, thereby leading to an overestimation of seed longevity. Therefore, in accordance with these results, the actual seed longevity of several alpine species may be lower than previously reported, highlighting that ex situ storage of alpine seeds might be even more problematic than currently thought. The coefficient of OESL developed here and its correlates (i.e. seed type, soil pH and seed longevity) may be used to prioritize species’ vulnerability to ex situ storage and to optimize viability testing, thereby reducing labour costs and enabling more effective conservation of seed collections. Alpine species are short-lived and most of them are incapable of becoming a seedling. Therefore, long-term storage of these species could be a problematic even under conventional seed banking conditions. As a solution, seed priming can be used to increase both seed longevity and seedling recovery. Therefore, I investigated the potential for priming to increase the longevity of six alpine species using a range of water potentials (hydro and osmo-priming). According to this study, priming treatments had a significant positive effect on seed longevity (p50 (RE) and p50 (NG)). In particular, hydro-priming was the most successful seed priming treatment to enhance both p50 (RE) and p50 (NG) and decreased the overestimation. The information provided in this study on wild alpine plants may fill some knowledge gap about how to monitor and improve seed viability in storage, which may have important implications high quality seeds both long- and short-term ex situ storage, such as in seed banks and native seed industry, respectively. In particular, I highlighted that normal germination (i.e. radicle plus cotyledon emergence) should be used to monitor seed viability during storage, that species from more humid soil may have higher possibility to show short-lived seeds and that, alpine seeds are short-lived, their longevity can be significantly improved using easy and inexpensive techniques, such as hydro and osmo-priming.