Effect of pre-soaking substrate and light availability on seed germination and seedling establishment of Dracaena draco (L.) L., a threatened species

The Dragon tree, Dracaena draco (L.) L., is an extremely threatened species. Its natural regeneration is disturbed and population appears to decrease rapidly. To design appropriate germination and seedling establishment protocols for a species conservation and restoration program, we studied the effects of pre-soaking, substrate and light availability treatment on seed germination for 15-day period. The condition for light availability corresponded to the sowing depth (at surface or at 2 cm depth). Germination occurred better in the dark when seeds were sown at 2 cm depth. Our results showed that D. draco seeds sown in the sand under dark condition and after 24 hours pre-soaking in warm water germinated better and recorded 82.5% of final germination percentage (FGP). However, seedlings grew better in potting soil and recorded 54 mm of length. The maximum FGP of 51.3% was recorded under light condition. These results indicate that sowing depth and light availability could be a limiting factor for D. draco seed germination in natural condition. Furthermore, the establishment of D. draco seedlings (shoot and root length) during an 8-week period in pots was also assessed and illustrated. More research on seed ecophysiology is required to understand the mechanisms controlling seed germination of D. draco in arid and semi-arid conditions viz. salinity and drought