Dormancy and germination: making every seed count in restoration

Abstract

From 50 to 90% of wild plant species worldwide produce seeds that are dormant upon maturity, with specific dormancy traits driven by species' occurrence geography, growth form, and genetic factors. While dormancy is a beneficial adaptation for intact natural systems, it can limit plant recruitment in restoration scenarios because seeds may take several seasons to lose dormancy and consequently show low or erratic germination. During this time, seed predation, weed competition, soil erosion, and seed viability loss can lead to plant re‐establishment failure. Understanding and considering seed dormancy and germination traits in restoration planning are thus critical to ensuring effective seed management and seed use efficiency. There are five known dormancy classes (physiological, physical, combinational, morphological, and morphophysiological), each requiring specific cues to alleviate dormancy and enable germination. The dormancy status of a seed can be determined through a series of simple steps that account for initial seed quality and assess germination across a range of environmental conditions. In this article, we outline the steps of the dormancy classification process and the various corresponding methodologies for ex situ dormancy alleviation. We also highlight the importance of record‐keeping and reporting of seed accession information (e.g. geographic coordinates of the seed collection location, cleaning and quality information, storage conditions, and dormancy testing data) to ensure that these factors are adequately considered in restoration planning.

Seed enhancement: getting seeds restoration‐ready

“…For imbibition to occur, the seed coat must be permeable to water (Kildisheva et al 2020). For seeds with a water‐impermeable seed coat, permeability must first be achieved by the opening of the water gap or through artificial means such as scarification or hot water treatment (Baskin & Baskin ).…”

Seed use in the field: delivering seeds for restoration success

“…In addition, seed pre‐treatments (e.g. scarification, application of chemical stimulants) may be required to relieve dormancy of some species (Kildisheva et al 2020). Seed coatings (e.g.…”

Ensuring seed quality in ecological restoration: native seed cleaning and testing

“…Because germination is the ultimate representation of viability in the natural environment, germination tests (see next section) are often interpreted as synonymous with viability. However, because seeds of many native plant species exhibit dormancy (Baskin & Baskin 2014; Kildisheva et al 2020), interpretation of germination data should be done in tandem with other measures (Pedrini & Dixon 2020). For example, if seeds are non‐dormant and germination conditions are well understood, a germination test can be considered equivalent to viability; however, it is recommended that all un‐germinated seeds that remain at the end of a test period are subject to a cut or TZ test (to estimate final viability) and are accounted for in the calculation of total germination percentage (Pedrini & Dixon 2020).…”

“…The test is terminated when the percentage of seed germination over time has remained unchanged and no more germination is recorded. Typically, the maximum duration of a commercial germination test is 4–6 weeks (Baskin & Baskin 2014; Kildisheva et al 2020). The portion of non‐germinated seeds at the end of the germination experiment could be either dormant or non‐viable.…”