SESAME CROP COEFFICIENTS USING CROP EVAPOTRANSPIRATION BY WATER BALANCE AND, REFERENCE EVAPOTRANSPIRATION BY PENMAN-MONTEITH1

Abstract

SESAME CROP COEFFICIENTS USING CROP EVAPOTRANSPIRATION BY WATER BALANCE AND, REFERENCE EVAPOTRANSPIRATION BY PENMAN-MONTEITH¹

JOSÉ RODRIGUES PEREIRA^*2; WHÉLLYSON PEREIRA ARAÚJO³; ÉRICA SAMARA ARAÚJO BARBOSA DE ALMEIDA⁴; JOSÉ RENATO CORTEZ BEZERRA⁵; HUGO ORLANDO CARVALLO GUERRA⁶ E JOÃO HENRIQUE ZONTA⁵

¹Thesis extract of the first author on the Campina Grande Federal University - UFCG, Campina Grande, Paraíba State, Brazil;

^*2Correspondent author; Agronomist, M. Sc., UFCG Agricultural Engineering Department/Doctor Degree Student; General Crops and Irrigation Department/Embrapa Cotton Researcher. Rua Oswaldo Cruz, 1.143, Centenário, Postal Code 58.428-095, Campina Grande, Paraíba State, Brazil. E-mail: jose.r.pereira@embrapa.br;

³Agronomist, M. Sc., UFCG Agricultural Engineering Department/Doctor Degree Student. Campina Grande, Paraíba State, Brazil. E-mail:wpacordao@hotmail.com;

⁴Agronomist. UFCG Agricultural Engineering Department/Master Degree Student. Campina Grande, Paraíba State, Brazil. E-mail: ericasamara@gmail.com;

⁵Dr., Irrigation Department/Embrapa Cotton Researcher. Campina Grande, Paraíba State, Brazil. E-mail: jose.cortez-bezerra@embrapa.br; joao-henrique.zonta@embrapa.br;

⁶Ph.D, UFCG Agricultural Engineering Department/Professor. Campina Grande, Paraíba State, Brazil. E-mail: hugo_carvallo@hotmail.com.

1 SUMMARY

To determine sesame BRS 196 CNPA G4 coefficients - Kc, at semiarid conditions, an experiment, irrigated with 100% of crop evapotranspiration - ETc, was installed at Embrapa Cotton, Barbalha County, Ceará State, Brazil, in 2012. It was measured, with a Diviner 2000® probe, each 10 cm soil depth, volumetric soil water content in three replications. The ETc (mm d^-1) was calculated by the soil water balance equation [ETc = I - Rs + D/C + ∆h, where I = irrigation flows (mm d^-1), Rs = runoff (mm d^-1), D/C = water drainage flows (mm d^-1) and, ∆h = soil water storage variation (mm d^-1)]. It was determined soil water retention curves and parameters (by Richards Plates and by van Genutchen method, respectively) and the saturated soil hydraulic conductivity (by infiltrometer method), too. To estimate the reference evapotranspiration – ET₀, data required by Penman-Monteith equation were obtained from the weather station of the National Meteorological Institute, Barbalha County, Ceará State, Brazil. It was concluded that the soil water balance method was able to determine the crop coefficient values for each phenological phase of the sesame BRS 196 CNPA G4, being equal to 0.63 (planting/establishment), 0.83 (growth), 0.97 (development/floration) and 0.56 (maturation).

KEYWORDS: Sesamum indicum L., water flows, water consumption.