Seed Desiccation Responses in Saraca asoca (Roxb.) W.J.de Wilde

Saraca asoca is one among the 36 endangered medicinal plants of South India. As seeds are the main propagule with short viability, the present study has been carried out to assess the level of dehydration tolerance as a prerequisite to maintain extended viability. The viability and vigour of the seeds declined when their moisture content was reduced by different methods of desiccation. The critical moisture content (CMC) of the seeds was found to be 45-46%. Irrespective of the method of drying, dehydration of seeds resulted in the loss of viability, confirming their recalcitrant nature. Desiccation responses were investigated by exposing the seeds to five different conditions: (a) 30° ± 2°C, (b) silica gel, (c) 40° ± 2°C, (d) 20° ± 2°C and (e) 0° ± 2°C. The duration for reaching the critical moisture level was the longest in seeds kept in an air-conditioned room (20° ± 2°C) and minimum for those kept in a freezer (0° ± 2°C). The lowest critical moisture level (36.3%) was observed in silica gel and highest (49.2%) under freezer condition. Both the attainment and level of CMC showed marked variation under different desiccation treatments, which indicates the influence of storage temperature on CMC of S. asoca seeds.