Factors affecting seed germination and emergence of Sophora davidii

• Tested range: 5 °C–40 °C.
• Optimum, upper and lower temperature was 20 °C, 35 °C, and 10 °C, respectively.
• Appropriate water and salt stress were 0–−0.4 MPa and 20–50 mM CaCl2, respectively.
• Appropriate seed burial depth ranged from 0 cm to 3 cm.

Sophora davidii is a popular ecological and feeding plant, but it also is a potential medicinal plant. Its root has high levels of lupin alkaloids, which make a kind of valued matrine-type alkaloids as one of the best alternatives to pentazocine. Very limited agronomic information exists regarding the cultivation of S. davidii as a medicinal and industrial crop. The objective of this study was to investigate seed germination and emergence of S. davidii in response to temperature, osmotic potential, salinity and depth of seed burial. The effect of temperature, osmotic potential and salinity on seed germination were examined at different temperatures (5–40 °C), while using different polyethylene glycol (PEG)-6000 (0–−1.0 MPa) and different CaCl2 (0–200 mM) solutions. Seedling emergence was also examined for seeds sown at different depths (0–9 cm). Temperature affected germination rates of S. davidii; maximum germination (30.67%) was reached at 25 days a constant temperature of 20 °C. Maximum germination rates were obtained under low osmotic potential (0–−0.4 MPa) and low salinity concentrations (20–50 mM CaCl2); increasing osmotic potential or salinity progressively inhibited seed germination. Deep burial significantly decreased seedling emergence rates, seedlings emerged well at depths of 0–3 cm, but no seedlings emerged from seeds buried at depths of ≥9 cm. As a general recommendation to growers S. davidii should be seeded no deeper than 3-cm depth, and the suitable environmental conditions (temperatures of 20–30 °C, water stress of 0–−0.4 MPa and salt stress of 20–50 mM CaCl2) may be encountered.