Evapotranspiration and crop coefficients for green-dwarf coconut in the coastal area of Ceará State, Brazil.

Abstract

There is little information about evapotranspiration and crop coefficient values for dwarf coconut irrigation scheduling. The study was carried out aiming to estimate crop evapotranspiration (ETc) and crop coefficients (Kc) during the coconut crop development and mid-season stages, in the coastal region of Ceará, Brazil. Plants of the Jiqui´s green dwarf coconut variety were used, which were planted on a 7.5 x 7.5 m triangular spacing, and irrigated using microsprinklers. ETc was estimated using the soil water balance method from the 11th to the 41th month after planting, using mercury tensiometer readings. ETo was estimated using the FAO Penman-Monteith equation. For the conditions where the study was performed, the green dwarf coconut ET varied from a minimum of 0.52 mm.d-1, at the 11th month after planting, to a maximum value of 5.01 mm.d-1, at the 36th month after planting. The crop development stage lasted until the 680th  day after planting (23th month after planting), when Kc values increased from 0.63 to 1.00. During the mid-season stage (flowering and fruit development stage) the average Kc value was 1.02.