Breaking Seed Dormancy during Dry Storage: A Useful Tool or Major Problem for Successful Restoration via Direct Seeding?

Abstract

To facilitate the restoration of disturbed vegetation, seeds of wild species are collected and held in dry storage, but often there is a shortage of seeds for this purpose. Thus, much research effort is expended to maximize the use of the available seeds and to ensure that they are nondormant when sown. Sowing nondormant (versus dormant) seeds in the field should increase the success of the restoration. Of the various treatments available to break seed dormancy, afterripening, that is, dormancy break during dry storage, is the most cost-effective. Seeds that can undergo afterripening have nondeep physiological dormancy, and this includes members of common families such as Asteraceae and Poaceae. In this review, we consider differences between species in terms of seed moisture content, temperature and time required for afterripening and discuss the conditions in which afterripening is rapid but could lead to seed aging and death if storage is too long. Attention is given to the induction of secondary dormancy in seeds that have become nondormant via afterripening and to the biochemical and molecular changes occurring in seeds during dry storage. Some recommendations are made for managing afterripening so that seeds are nondormant at the time for sowing. The most important recommendation probably is that germination responses of the seeds need to be monitored for germinability/viability during the storage period.

Thermal Requirements Underpinning Germination Allude to Risk of Species Decline from Climate Warming

“…And finally, although storage conditions were similar across collections, seeds were stored for varying lengths of time and storage duration may have impacted on thermal requirements of collections by broadening the germination niche of some species. Storage time is known to affect germination success in some species with high levels of dormancy [ 68 , 69 ] and long periods of storage under conditions that promote after-ripening may result in seeds entering secondary dormancy or even losing viability [ 70 ].…”

Green hay transfer for grassland restoration: species capture and establishment

“…For example, the seeds of many U.K. grassland forbs and sedges display primary physiological seed dormancy at the time of seed shedding, and require afterripening to become germinable (Grime et al 1981). For a subset of these species that is characterized by nondeep physiological dormancy, dry storage prior to sowing may provide sufficient afterripening to allow germination when sown (Baskin & Baskin 2020), and germination testing prior to sowing can help confirm if this is the case. For other species, whose germination requirements might be more complex, specific methodologies for ex situ dormancy alleviation can and should be applied (Kildisheva et al 2020) prior to sowing, to ensure efficient germination.…”

Seed Functional Traits Provide Support for Ecological Restoration and ex situ Conservation in the Threatened Amazon Ironstone Outcrop Flora

“…In turn, seeds of Cavalcantia glomerata and Brasilianthus carajensis showed 23.3 and 18% increase in germination, respectively, after storage. For these species, after ripening can be a successful strategy for restoration via direct seeding (Baskin and Baskin, 2020). Maddison and Slatkin (1991) method for phylogenetic signal in the temperature range and dormancy categorical traits, highlighting in bold the traits with significant values.…”