Management of Nitrogen and Phosphorus in Castor Bean Culture

Abstract

: The castor bean ( Ricinus comunis L.), also known as carrapateira, is demanding in nutrients, presenting good response in productivity to fertilization. Preferably, planting is recommended in well-prepared, fertile, deep and loose soils, to allow the development of the root system. This work aimed to evaluate the response of a cultivar (BRS Energy) and a lineage (CNPA 2009-7) of castor bean to increasing doses of N and P in the soil in two locations in the northeastern semi-arid region: rural areas of the municipalities of Apodi (RN ) and Barbalha (CE). The doses of N tested were: 0, 50, 100, 150 and 200 kg/ ha and those of P, 0, 50, 100, 150 and 200 kg/ha. The experiments were distributed in randomized blocks with four replications, making a total of 40 plots. The cv. BRS Energy showed a greater absorption of nitrogen in the soil and, consequently, synthesized more crude protein than the CNPA 2009-7 genotype. In addition, it showed greater efficiency in calcium absorption. On the other hand, the genotype proved to be more efficient in the absorption of phosphorus and magnesium. The cultivar naturally showed a higher castor bean production, as evidenced by the significantly higher variables related to the production of fruits and seeds. It also had a higher oil content in relation to the genotype. In both locations, the content of N and, consequently, of proteins, in castor bean leaves increased as a function of the dose of nitrogen fertilizer.