Seed bank dynamics of an invasive alien species, Helianthus annuus L.

Abstract

Aims The ability to form persistent seed banks is one of the best predictors of species’ potential to establish in new ranges. Wild sunflower is native to North America where the formation of persistent seed banks is promoted by disturbance and it plays a key role on the establishment and persistence of native populations. However, the role of the seed banks on the establishment and persistence of invasive populations has not been studied. Here, we evaluated the role of seed bank and disturbance on the establishment and fitness, and seed persistence in the soil in several sunflower biotypes collected in ruderal (wild Helianthus annuus) and agrestal (natural crop–wild hybrid) habitats of Argentina as well as volunteer populations (progeny of commercial cultivars). Methods In a seed-bank experiment, we evaluated emergence, survival to reproduction, survival of emerged seedlings, inflorescences per plant and per plot under disturbed and undisturbed conditions over 2 years; in a seed-burial experiment, we evaluated seed persistence in the soil over four springs (6, 18, 30 and 42 months). Important Findings Overall, seedling emergence was early in the growing season (during winter), and it was promoted by disturbance, especially in the first year. Despite this, the number of inflorescences per plot was similar under both conditions, especially in ruderals. In the second year, emergence from the seed bank was much lower, but the survival rate was higher. In the seed-burial experiment, genetic differences were observed but seeds of ruderals and agrestals persisted up to 42 months while seeds of the volunteer did not persist longer than 6 months. The agrestal biotype showed an intermediate behavior between ruderals and volunteers in both experiments. Our findings showed that wild and crop–wild sunflower can form persistent seed banks outside its native range and that disturbance may facilitate its establishment in new areas.

Maternal control of early life history traits affects overwinter survival and seedling phenotypes in sunflower (Helianthus annuus L.)

“…In contrast, in a recent seed bank study, no differences in the timing of emergence were observed between the high dormant BAR and the low dormant CROP and DIA, all biotypes showed similar emergence timing during late winter (Presotto et al . 2020). Such differences may be attributable to the environmental conditions that seeds experienced after dispersal in the different experiments.…”

“…Second, in the soil seed bank, seed persistence is influenced by seed characteristics (seed size, dormancy, longevity), by local climate (temperature, humidity) and by external factors such as human disturbance with agricultural machinery (Presotto et al . 2020). Finally, a successful establishment of overwinter survivals will depend on seedlings´ tolerance to intraspecific and interspecific competence (Mercer et al .…”

“…2020), probably because of natural selection for early winter emergence in Argentina (Presotto et al . 2020). In reciprocal hybrids between CROP and DIA, we observed strong maternal effects on phenotypic traits and overwinter seedling survival.…”

Seed bank persistence of a South American cordgrass in invaded northern Atlantic and Pacific Coast estuaries

“…Invasive species usually germinate from persistent seed banks after disturbances that alter environmental conditions such as light and temperature ( Presotto et al 2020 ). Seeds can be resistant to environmental stresses (i.e.…”

Rapid evolution of seed dormancy during sunflower de-domestication

“…Among these traits, seed dormancy and herbicide resistance are among the most important for the successful establishment of weeds. Seed dormancy plays a crucial ecological role, contributing to avoidance of out of season germination (Presotto et al, 2020; Hernández et al, 2021), and persistence in soil seed banks (Darmency et al, 2017; Pipatpongpinyo et al, 2020; Presotto et al, 2020). On the other hand, the high killing rates associated with herbicide applications exert strong selection pressure for herbicide resistance (Darmency et al, 2017; Kreiner et al, 2018; Tranel and Wright, 2002).…”