NPK fertilization and sowing time for castor plant. II - reproductive and vegetative stages components

Abstract

The objective of this work was to investigate the components of reproductive and vegetative stages of the castor bean cultivars submitted to mineral fertilizer, sowing times and locations. The experiments were conducted at the CCA/UFC in Pentecoste and the CENTEC in Limoeiro do Norte, Ceará, Brazil. The treatments consisted on four doses of NPK fertilizer (00-00-00; 40-25-15; 80-50-30 and 120-75-45 of N-P₂O₅-K₂O), two castor bean cultivars (BRS Nordestina and Mirante 10); two sowing times (early sowing and dry sowing) and two locations (Pentecoste and Limoeiro do Norte), in a randomized block design with four replications of a factorial arrangement 4x2³. In Pentecost the cv. Mirante 10 increases in height growth, stem diameter, number of racemes and prolong its flowering when there is an increase in the supply of nutrients combined with supplemental water in early sowing. In Limoeiro do Norte the cv. BRS Nordestina produces racemes largest in dry sowing due to the lower number of racemes produced, less chance of competing in the same plant. The smallest amount of water available to plants in the cultivation of drought, most evident in Limoeiro do Norte, affects the vegetative and reproductive structures of castor beans and is a most important factor in altitudes below 300 m.