SEED AND SEEDLING SIZE RELATIONSHIP IN CASTOR (RICINUS COMMUNIS L.)

The seed weight in Castor (Ricinus communis L.) averaged to 309.99 ± 0.16.016 mg and varied 15.4-folds i.e. around 51.4%. The seed weight distribution was asymmetrical (negatively skewed) and platykurtic. Out of 101 seeds sawn (seed weight: 33.7 - 515.8 mg), twenty seven seeds of seed weight varying from 33.7 to 245.5mg could not germinate. Within the range from 248.6 to 515.8 mg, the seed weight appears not to influence the final seedling emergence percentage. The critical seed weight to affect emergence, therefore, appeared to be around 248 mg. Larger seeds gave rise to larger seedlings. The cotyledons developing from larger seeds were larger in size. The hypocotyl length related with seed size in curvilinear fashion but varied greatly and their lengths could be accounted for only around 10% by the seed weights. The seed size, on the other hand, influenced stem dry weight quite effectively. The dry weight of the seedlings (roots + stem + cotyledons + leaves) increased significantly (r = 0.6582, p < 0.00001) with the increase in seed weight. Pigments such as Chlorophyll-a, chlorophyll-b, total chlorophylls and carotenoids concentrations were not significantly affected by the seed size within the range of 248.6 to 484.2 mg.