The Influence of Seed Quality, Dormancy Breaking, and Water Stress on Germination of Pollinator Species for Biodiversity Enhancement

The lack of protocols for breaking seed dormancy, inconsistent seed quality, and abiotic stress factors such as drought impede large-scale restoration efforts of pollinator seed species. This research explores the germination response, dormancy-breaking techniques, and water stress tolerance in selected pollinator-friendly plant species with characteristics facilitating mechanized rehabilitation protocols and biodiversity enhancement. Furthermore, this study supports utilization of Multiple Seed Pellets (MSP), to facilitate mechanical sowing of pollinator seeds. Forty-two commercial seed lots representing seven plant families with 28 species were evaluated under two alternating temperature regimes (15/25°C and 20/30°C) with and without gibberellic acid (GA₃) pre-treatment. GA₃ significantly enhanced germination percentage, and reduced T₅₀ (time to 50% germination) across most seed lots. Overall, germination was higher and faster at 20/30°C than 15/25°C. Six species were further examined for dormancy-breaking responses to GA₃ and kinetin applied in a hydrogen peroxide (H₂O₂), soak. GA₃ + H₂O₂ had the greatest germination compared to other treatments. The effect of water stress on seed germination was assessed in controlled chambers at soil water potentials of −1.08, −0.75, −0.13, and 0 MPa. Milkweed species (A. incarnata, A. syriaca, and A. tuberosa) exhibited consistently high germination across a broad moisture range of -0.75 to 0 MPa. In contrast, Echinacea purpurea required high moisture levels (-0.13 to 0 MPa) for optimal germination. Monarda fistulosa and Rudbeckia hirta showed their best performance under moderate moisture conditions (-0.13 MPa). The use of GA₃ to break physiological seed dormancy offers a promising approach to enhance germination. With the utilization of MSP technology, these strategies provide scalable, practical tools to improve native seed performance and advance pollinator habitat restoration in agroecosystems.