Comportamento e necessidades hídricas do gergelim sob diferentes regimes de irrigação.

Abstract

Behavior and water requirements of sesame under different irrigation regimes. In order to determine lhe growth and production behavior and the water consumption of the sesame BRS 196 CNPA G4 crop on different irrigation regimes, it was carried out, at Embrapa Cotton, Barbalha County, Ceará State, Brazil, in 2012, an study outlined in randomized blocks with four irrigation treatments (irrigation depths of 305, 436, 567 and 698 mm on the cycle, being the 567 mm irrigation depth equal de 100% of the ETc), distributed in plots with three replications. The crop evapotranspiration (ETc), used to calculated the irrigation depths, was calculated multiplyng the reference evapotranspiration (ETo) calculet by the Penmann Monteith method with climatological data obtained from an Station located in the Nacional Meteorological Institute, Barbalha County, CE State, by the crop coefficients (Kc) recommended by FAO. The in situ sesame crop evapotranspiration (ETc) was obtained by the soil water balance. The plant variables analyzed were plant height, stem diameter, leaf area, leaf area index ant the absolute and relative growthe rates of plant heigth, stem diameter and leaf area. At harvest it was measured capsules/fruits number and determined the yield, the oil content of the seeds, the water stress response factor (Ky) ant the water usa efficiency (WUE). Sesame plant heigthe, steam diameter, leaf area and leaf area and leaf area indez increased with irrigation being obtained the greatest values antil 70 or 75 days after emergence (DAE) in general on the 698 mm irrigation depthe . The highest yeld and oil content of the seeds was obtained with the irrigation deph of 698 mm and the 305 mm proportionated the best WUE. The medium sesame Kc was 0.45 for the establishmente phase, 0.62 for the growth, 0.97 for the floration and 0.57 for the maturation phase. The Ky (0.77) indicated that sesame plants are tolerant to lack of soil water.