Adubação NPK no comportamento agronômico da mamona cultivar BRS 149 nordestina em ambiente protegido.

Abstract

The castor bean plant is known in Brazil under many names such as: mamoneira, ricin,tick, bafureiro, berry and palm of Christ. The oil is the most important constituent obtamed from the castor bean. From its extraction, pies remain the most relevant byproduct so far made. It's a plant that requires many nutrients, showing a high concentration of oil and proteins in its seeds, which leads to a demand of essential elements, especially nitrogen, potassium, phosphorus, calcium and magnesium. The balance of the nutrients, when considering crop production, is indispensable to soil fertility. The aim of this paper was to evaluate the performance of the Northeastern castor bean cultivar, grown in a greenhouse, in relation to increasing dosages of nitrogen (N), phosphorus (P) and potassium (K). For the first experiment, conducted under a greenhouse, five increasing doses of nitrogen (Di=40; D2=80; D3=120; D4=160 and D5=200 Kg of N/ha) were used along with fixed doses of phosphorus and potassium. As for the second experiment, five increasing doses of phosphorus (Di=30; D2=6U; D3=90; D4=120 e D5= 150 Kg of P/ha) and fixed doses of N and K, were applied. Finally, the third experiment was conducted applying five increasing doses of potassium (D,=30; D2=60; D3=90; D4=120 e D5= 150 Kg of K/ha) in addition to fixed doses of N and P. The castor bean plants' heights were influenced by the increasing doses of phosphorus. The number of leaves, leaf area, stem diameter, number of capsules, phytomass, seeds and seeds weight showed significant yield once applied higher doses of nitrogen fertilizer. As for the amount of oil in ali fertilizers and dosages studied, the results were lower than the ones found in the studied literature.