MSc

An investigation was conducted on “Seed source variation in the seed and seedling characters of ashoka [Saraca asoca (Roxb.) de Wilde]” in the nursery of College of Forestry, Kerala Agricultural University, Thrissur, Kerala, India. In order to fix the seed sources, the state was divided into six equal portions based on the latitude. The seeds collected from each source were bulked and used for the study. Seed traits, germination attributes and seedling characters were used for investigating seed source variation in Saraca asoca. Different seed traits like seed length, seed breadth, seed length to breadth ratio, seed weight and pericarp thickness was evaluated in the present investigation. Study showed significantly lower size for the seeds collected from seed source SS 3. The performance of seed source SS 1, SS 2, SS 4 and SS 6, were on par with each other in case of most of the seed attributes.

In the present study altogether 2400 seeds were sown, with 400 seeds representing each seed source. Germination of seeds were noted daily. In general germination per cent in Saraca asoca was found to be good with an average of 81.5 per cent. Maximum germination per cent was exhibited by seed source SS 1 (98 per cent). Germination per cent of seed source SS 2 was also on par with SS 1, with a recorded value of 93.8 per cent. Significantly lower germination per cent was shown by seed source SS 5 (37.8 per cent). This may be attributed towards the presence of mostly non viable seeds in seed source SS 5. Apart from germination percentage, days required for germination to initiate, days required for germination to cease, germination days, days required for attaining 50 per cent of germination, germination energy, mean daily germination, peak value and germination value of Saraca asoca was assessed. Most of the germination attributes were the least in case of seed source SS 5.
A number of seedling parameters like height, collar diameter, number of leaves, leaf area, number of branches, leaf thickness, fresh weight of shoot and root dry weight of shoot and root, shoot to root dry weight ratio, relative growth rate, chlorophyll content and photosynthetic rate was measured. The study showed seed source SS 1, SS 2 and SS 4 to be the best followed by seed source SS 3 and SS 6. However the variation with respect to seed source SS 5 was significantly the lowest in most of the attributes studied. The cluster analysis revealed seed sources SS 2 and SS 4 along with seed sources SS 3 and SS 6 to be genetically closer. A highly distant relationship was exhibited by seed source SS 5 with rest of the seed sources.

Apart from the seed source variation study, karyomorphhological analysis was also carried out in ashoka. The study revealed 2n = 34 chromosomes, in Saraca asoca. In order to standardize the procedure for cytological preparation two pre- treatment chemicals namely 8-hydroxyquinoline and colchicine were used. Two fixatives Carnoys I and Carnoys II were used in the present study. For staining acetocarmine and fuelgen were used. It was found that pretreating the chemicals with 8-hydroxyquinoline and fixing it in Carnoys II and using the stain acetocarmine gave the best cytological preparation.