From stubborn seeds to thriving plants: Enhancing germination success of hard-to-germinate native Dutch plant species for conservation and restoration efforts.

Abstract

In the Netherlands, climate change and excessive nitrogen deposition have led to the degradation of natural ecosystems. Consequently, the need for successful restoration has increased. Seed-based restoration is an effective approach in many instances. However, a limitation of this approach is that wild species are often difficult to germinate. This review aims to enhance seed production for restoration by increasing knowledge of seed development, dormancy, germination, and treatments for enhancing germination. Many general mechanisms are shared across plant species, including the acquisition of desiccation tolerance and dormancy, dormancy breaking factors, and the importance of the ABA:GA ratio throughout seed development and germination. However, many aspects vary significantly between species, such as dormancy type, requirements for breaking dormancy, and the effectiveness of different germination enhancement treatments. Therefore, a species-specific approach is necessary for improving germination. An analysis was done on several native Dutch wild species, including Alliaria petiolate, Succisa pratensis, Knautia arvensis, Viola odorata, Viola canina, Viola palustris, Caltha palustris, Fumaria officinalis, and Dipsacus pilosus, and the most effective germination enhancing treatment is proposed. The most commonly effective treatments include cold stratification, gibberellin treatment, scarification, or a combination of these treatments. There are many gaps in knowledge on most wild species, and more research is essential. Ultimately, the findings of this review can give valuable insights into the mechanisms behind dormancy and germination. Additionally, this review offers an overview of effective treatments for enhancing germination in native Dutch wild species, which contributes to the improvement of restoration efforts.