Um experimento foi conduzido em estufa, na UFCG, com plantas de mamona (Ricinus communis L.), cv BRS Nordestina, para avaliar os efeitos do nitrogênio, fósforo e potássio no crescimento das mesmas. Utilizou-se delineamento inteiramente casualizado com três repetições e quinze tratamentos, em distribuição de matriz baconiana, com as doses de referência: 40:90:60 kg ha-1 de N:P2O5:K2O. Dados sobre a altura da planta, diâmetro caulinar, número e comprimento das folhas foram medidos aos 20, 40, 60, 80, 100, 120 e 140 dias após o plantio (DAP). A adubação desbalanceada afetou o desenvolvimento da mamoneira, tendo, as melhores respostas das plantas, sido observadas com as doses de 200 kg ha-1 de N; 150 kg ha-1 de P2O5 e 150 kg

A trial was carried out in a greenhouse located at the Federal University of Campina Grande, in Campina Grande, Paraiba State, Brazil, with castor bean plants (Ricinus communis L.), cv BRS Nordestina, in order to evaluate the effects of nitrogen, phosphorus and potassium on the growth. A completely randomized design with three replications and 15 treatments originated from a baconian matrix was adopted. Reference doses were 40:90:60 kg ha-1 of N:P2O5:K2O, respectively. Plant height, stem diameter, number and length of leaves were measured at 20, 40, 60, 80, 100, 120 and 140 days after planting (DAP). The unbalanced fertilization affected the development and seed production of castor bean, and the best response of the plants was observed at levels of 200 kg ha-1 de N; 150 kg ha-1 de P2O5 and 150 kg ha-1 de K2O. Key-words: Ricinus communis L., mineral nutrition, fertilization.