Overcoming root dormancy and identifying the storage behaviour of Lilium polyphyllum seeds

Abstract

Lilium polyphyllum D.Don ex Royle is a critically endangered medicinal herb of Himalaya. Seeds have epicotyl morphophysiological dormancy, and in the field a minimum of 34 weeks is required for root emergence. To date, treatments to decrease the time for root protrusion and seed storage behaviour have not been determined. We evaluated the effects of plant growth regulators and nitrogenous compounds as well as seed scarification on root emergence, and determined the storage behaviour of seeds. Root emergence at 20 °C was significantly increased by 100 ppm of indole butyric acid (IBA), KNO3, and thiourea, and by the application of NaOCl solution for 30 min. The mean germination time was significantly decreased by 50 ppm of gibberellic acid (GA3; 28 days) compared with 100 ppm GA3 (36 days). After 12 months of dry storage, the viability of seeds (TTC method) at room temperature (10–35 °C), 0–4 °C, and −20 ± 1 °C was 95%, 100%, and 100%, respectively; thus, the seeds have orthodox storage behaviour. Our recommendation for seedling production is to store the seeds at room temperature until they can be sown under warm wet conditions. Roots emerge after about 8 weeks, and then seeds should be given a 2-week cold moist treatment to break shoot dormancy. After 2 weeks of cold, transfer the seeds to warm (20 °C) spring temperature conditions to promote growth.