Yield Response of Castor (Ricinus Communis L.) to Different Nitrogen and Phosphorus Fertilization

Castor (Ricinus communis L.) is considered to be one of the most promising nonedible oil crops, due to its high annual seed production and yield and adaptability to semiarid climate and adverse growing conditions. Castor shows a great potential as a bioenergy and industrial feedstock due to its high oil content, wide range of environmental adaptation including the ability to growth on marginal soils. The aim of this study was to investigate the response of castor to different doses of mineral macronutrients in order to increase seed yield. The experiment was arranged in a randomized block design and two experimental factors were studied: three mineral Nitrogen fertilization rates (0, 120 and 180 kg N ha-1) and three mineral Phosphorus fertilization rates (0, 60 and 120 kg P2O5 ha-1), with three replicates per block. The highest seed yield was obtained by P120 N180 treatment; however, the combination of a high soil nitrogen level (N180) and medium phosphorus availability (P60) resulted in satisfactory seed yield. The higher N and P supply (N180 - P120) led to longer phenological stages, which delayed the physiological maturation of primary and secondary racemes in comparison to others treatments.