Dormancy,viability and germination of Magnolia lanuginosa (Wall.) Figlar & Noot. seeds: A threatened tree species of Northeast India

The population of Magnolia lanuginosa a rare tree species of northeastern India has declined drastically owing to habitat destruction, low natural regeneration and over harvesting for its multipurpose uses. The present study was carried out to understand the type of dormancy and analyse the effect of storage on viability and germination behaviour of M. lanuginosa under various physical and chemical treatments. Seeds subjected to physical treatments such as water (cold, hot, and boiling), acid (H₂SO₄) and manual scarification failed in breaking dormancy. Seeds treated with growth regulators (GA₃) had a significant effect on germination. It reduced the germination time and the shortest T₅₀ was observed in seeds treated with 2000 mg/l of GA₃ (non-scarified seeds) and 1000 mg/l of GA₃ (scarified seeds). The use of KNO₃ did not have any significant effect in breaking dormancy. However, the use of KNO₃ along with GA₃, increased the germination percentage. Seeds cold stratified (CS) for 60 days at 5 °C was effective in breaking dormancy and resulted in 84.26% germination. This indicates the prevalence of Type-1 Non deep physiological dormancy in M. lanuginosa seeds that requires a crucial CS period for proper embryo growth and development. The seeds stored in moist sand at 5 °C remained viable even after 120 days with 48.88% viability. The study would be helpful in devising seed germination protocols for mass production and reintroduction of the species into the wild.