Consumo hídrico e exigência térmica da palma forrageira em ambiente semiárido

The objective of this study was to evaluate water consumption and establish the thermal requirement of three varieties of forage palm in different stages of development in a semiarid environment. The experiment was carried out under field conditions in the municipality of Santa Luzia, PB, Poco Redondo Farm. To determine the culture evapotranspiration (ETc), three drainage lysimeters located in the center of the experimental area were used. Each lysimeter contained four plants with similar characteristics and under the same management system as the external plants. A fourth lysimeter was used with grass to determine the reference evapotranspiration ET0. Each lysimeter represents an effective evaporation area of 1.17 m2. By the order of emission of the cladodes together with the sum of degrees days, the four phenophases of the forage palm were determined. The reference evapotranspiration was 7.2 mm dia-1. The evapotranspiration values of ETc culture and cultivation coefficient (Kc), were respectively: 4.8; 4.8 and 4.6 mm dia-1 and 0.72; 0.70 and 0.70, for Orelha the Elefante, Baiana and Miuda varieties. The basal temperature was 18 °C and the thermal sum accumulated in the period was over 4000 °C.