Castor bean (Ricinus communis L.) is an oleaginous of high economic value because its oil has numerous applications in the industry, such as in the manufacture of enamels and paints. Presently, its production is aimed at being used as a biodiesel. The main obstacle to a high production is the survival of the young plants in field in a no-tillage system. An alternative would be the production of seedlings. The objective of this research was to evaluate the initial growth of BRS Gabriela (R. communis L.) castor bean seedlings in function of different substrates and container volumes. The work was conducted at the nursery of the State University of Paraíba (UEPB), Catolé do Rocha, PB, Brazil. The experimental design was completely randomized (CRB) in a 4 × 2 factorial design with 6 replications. The factors consisted of 4 container volumes: 1, 0.5, 0.3, and 0.27 dm-3 and 2 substrates (S1 = 50% soil and 50% earthworm humus, and S2 = 40% soil, 30% earthworm humus and 30% sand). The analyzed variables were stem dry matter (SDM), root dry matter (RDM), plant leaf area (PLA), leaf biomass (LPM), stem biomass (SPM), water content (WC), plant height and stem diameter ratio (PHe/SD), root dry matter and dry shoot dry matter ratio (RDM/SDM), Dickson quality index (DQI) and succulence. The morphological characteristics were influenced by container volume and substrate. The largest container volume, together with the substrate S1 (50% soil and 50% earthworm humus), provided viable seedlings ready to be transplanted to the field.
Key words: Ricinus communis L., Initial growth, greenhouse, earthworm humus.