Seed size and its influence on germination, seedling growth and biomass in Saraca asoca (Roxb). De Wilde, critically endangered tree species of Western ghats, India

Abstract

Saraca asoca (Roxb). De Wilde is one of the high traded medicinal plant species of India. There is a huge demand for bark of this species both in domestic and international markets. There is a demand for quality planting materials for large scale plantation. Forest department and farmers have already initiated captive plantation of this species. Several factors affect the seedling quality in nursery. Seed grading is one among them. The present study aims at understand the influence of seed size on seed germination and seedling vigour in S. asoca. Association study showed that seed length was positively correlated with seed weight (r= 0.887), seed width (r=0.697) and thickness (r=0.621). Therefore, seed length was used to categorize seedlot into small (< 30.0 mm), medium (30.1-40.0 mm) and large (> 40.1 mm) seeds. Result showed that larger seeds produced maximum germination (86.7%) as compared to smaller seeds (45.0%). Moreover, larger seeds attained higher collar diameter (3.34 mm) and dry biomass viz., leaf biomass (0.91 g), shoot biomass (0.31 g), root biomass (0.95 g) and entire seedling biomass (2.17 g) as compared to smaller seeds. Seedlings raised from medium seeds were at par with larger seeds in most of the traits. Therefore, it is suggested to use seedlot having > 30 mm length, preferably larger seeds (> 40 mm) in the nursery for better establishment of quality seedlings.