Impact of Seed Size on the Seedling Vigour, Dry Matter Yield and Oil Content of Jatropha (Jatropha curcas L.)

Seed size is a trait of the plant that affects seed germination and seedling survival. This study aims to assess the growth response of J. curcas to different seed sizes. A pot experiment was conducted to evaluate the effects of J. curcas seed sizes on the seedling vigour and seed component. The seeds were fractioned into three sizes visually into: large, medium and small and by 1000 seeds weight (SW). Seedling vigour was assessed by: germination % (G%), seedling length cm (SL), seedling vigour index, SVI, seedling growth rate, SGR, and speed of germination, SOG as well as proportion of cake, shell and oil content (OC) expressed as% of the seed. Results obtained shows that G% and the SOG were not affected by seed sizes but by other factors within the seed. However, seedling vigour expressed as SL, SVI and SGR increased significantly (P ≤ 0.05) with increase in seed sizes. Proportion of cake, shell and oil component of J. curcas seeds increased with increasing seed sizes while 60% of the seed is made up of the cake from where the oil is extracted. Dry matter yield, DMY significantly (P ≤ 0.05) increased with increase in seed size from 6.41 g/plant in large seeds to 2.61 g/plant in small seeds. There is positive and strong significant correlation between, SW and DMY (r = 0.91**), yield increase (r = 0.82**), OC (r = 0.85**), % cake (r = 0.94**). Findings revealed that larger seed had higher potential of producing vigorous plants with eventual high crop yield and higher OC.