MESQUITA, E. F.; http://lattes.cnpq.br/3678539134744796; MESQUITA, Evandro Franklin de.
Resumo:
The fertilization is a practice that normally increases the productivity of the cultures.
Considering that the NPK needs of the castor bean are still unknown an study was
conducted aiming to evaluate the effects of nitrogen, phosphorus and potassium on the
growth and production of castor bean (Ricinus communis L.) cultivar BRS 188
Nordestina and BRS 149 Paraguaçu. For this, two experiments were installed in a
greenhouse using a 2 x 2 x 2 factorial design completely randomized subjected to two
leveis of nitrogen (Ni=200 and N2=300 kg ha"1), two leveis of phosphorus (Pi=150 and
P2=250 kg ha"1) and two leveis of potassium (Ki=150 and K2=250 kg ha'1) with three
replicates, totalizing 24 experimental units. The testimony corresponded to the
treatment with the lowest leveis of NPK (N1P1K1). Soil water content was maintained at
field capacity and monitored daily using a DIVTNER probe inserted into the soil
throughout an access tube installed in each vase. Plant height, stem diameter, number
and length of leaves were measured at 20, 40, 60, 80, 100,120, 140 and 160 days after
planting. Castor bean production was evaluated measuring the length and weight of the
raceme, the number of fruits, the amount of seeds by raceme, weight of 100 seeds, and
oil and protein content of the seed. The combined application of the highest leveis of
nitrogen, phosphorus and potassium was not enough for the plants to develop its
productive potential. Nitrogen was the nutrient that promoted the highest growth,
development and yield of the two cultivars. On fructification, both castor beans
cultivars presented low content of nitrogen, phosphorus, potassium, calcium and sulfur
and high contents of magnesium. Independently of the NPK leveis studied, the oil
content of the seeds was under the ideal and admitted levei. Although the oil content of
the seed was low, the nitrogen application increased the seed oil content. The
application of nitrogen increased significantly the protein production.