EVAPOTRANSPIRATION ESTIMATE OF CASTOR BEAN (Ricinus communis L.) cv. BRS ENERGIA IRRIGATED WITH DIFFERENT SALINE WATER LEVELS

In the Federal Institute of Bahia State, City of Senhor do Bonfim, northeastern Brazil, it was conducted a study of verification of saline stress of the shrubby castor bean (Ricinus communis L.) cv. BRS Energia. This plant usually grows in rainfed agriculture, an important characteristic for family small farmers in this typically semiarid region, and was chosen because it is a source of raw material for extraction of biodiesel. The average growth cycle of this variety is 120 d. Plants were grown in drainage lysimeters and irrigated with water with seven levels of salinity (electrical conductivity, ECa): 0.12 (control), 0.8, 1.6, 2.4, 3.2, 4.0 and 4.8 dS m(-1), to quantify the absorbed water and evapotranspiration (ET). The experiment began in September 2008, and ended at 79 d after germination (DAG). A completely randomized design was used with three replicates and 21 experimental units. Data analysis was performed using the program SISVAR (p <= 0.05). There was a gradual influence on water absorption by plants according to the saline level; thus, the higher absorption (2134.67 L) was with the treatment with lower ECa and the lowest (1051.12 L) with treatment with higher ECa, throughout the study period.