Effect of some plant extracts on seed mycoflora, germination and seedling vigour of castor (Ricinus communis L.)

Castor leaf is the primary food of eri silkworm Samia cynthia ricini Boisduval. The quality of seed is an important factor that determines the germination, initial establishment, seed yield and export value of castor oil as well as the leaf yield and its quality for eri silkworm rearing. In the present study, effect or leaf extracts of Aristolocbia indica, Boerhaavia diffusa, Catharanthus roseus and Tribulus terrestris was studied on seed mycoflora, germination and seedling vigour of castor. The extract of T. terrestris was the most effective to control the growth of mycoflora on castor seeds. This was followed by the extract of C. roseus. The leaf extracts of all the four plants tested have little adverse effect on seed germination and seedling vigour. The extracts of B. diffusa and C roseus have more adverse effect on germination and seedling vigour compared to the extracts of A. indica and T. terrestris. The seedling vigour was also reduced when the seeds were treated with the niracts. The probable reasons for the suppression of mycoflora and the adverse effect on seed germination and seedling vigour are discussed in the paper.