Effect of seed weight on seed vigour and early seedling growth of Jatropha curcas, a biodiesel plant

The effect of seed weight on germination and seedling growth was investigated in Jatropha curcas, a tree-borne oilseed species, currently developed worldwide as a feedstock for biodiesel production. Seed weight was highly variable, from 0.28 to 0.81 g. Seed germination rate was significantly affected by seed weight: 46.2, 79.3, 84.5, and 95.3% for seeds in weight ranges, <= 0.39, 0.4-0.49, 0.5-0.59, and >= 0.6 g, respectively. Seedling shoot-length and dry matter yield were significantly affected by seed weight. Seedlings grown from the heaviest seeds were 51% taller and 91% heavier than those from the lightest ones. Indirect analyses of seed vigour indicated a significant linear relationship between results of tetrazolium reduction and electrical conductivity assays and seed weight: as seed weight increased, tetrazolium reduction increased, and electrical conductivity decreased. Our results suggest that improved seed and seedling quality, as associated with greater seed weight, is attributed to better membrane integrity and increased availability of energy in the endosperm. Tetrazolium reduction and electrical conductivity assays were proven to be efficient methods to estimate J. curcas seed vigour and seedling performance and thereby to promote planting of higher quality transplants in the field.