Evapotranspiration and crop coefficients of melon plants measured by lysimeter and estimated according to FAO 56 methodology

Talyana K De Melo,José E Sobrinho,Paulo S De Souza,José F De Medeiros,Vladimir B Figueiredo

doi:10.1590/s0100-69162013000500005

Abstract

Aiming at contributing to an adequate management of water resources, this study aimed to analyze and compare evapotranspiration (ETc) and crop coefficients (Kc) of melon plants measured by a lysimeter and estimated according to the FAO 56 methodology, in the city of Mossoró, state of Rio Grande do Norte (RN), Brazil. In order to measure ETc, weighing lysimeters with an area of 2.25m² were used, with two repetitions. The Penman-Monteith equation parameterized by FAO was used to estimate the reference evapotranspiration, and crop coefficients were those recommended in FAO-56 Bulletin adjusted to local climatic conditions. The required climatic data and lysimeter measurements were collected by an automatic weather station installed at the site. The results were compared by means of statistical indicators: of precision (r), of accuracy (d), and performance (c), in daily and weekly intervals. The data estimated by the FAO 56 methodology were adjusted optimally to the values measured by the lysimeters in accordance with index "c" in the two time scales assessed, indicating the potential of the method proposed by FAO to irrigation management in the climatic conditions of Agripole Assú-Mossoró.

Highlights

The semiarid region of Brazil has a recognized potential of being a major producer of tropical fruits
It becomes necessary to use suitable coefficients, crop coefficients (Kc), determined based on the crop evapotranspiration (ETc) and reference evapotranspiration (ETo), whose estimates allow the assessment of the amounts of water to be applied in crops
There is very few research data related to these coefficients, especially in the semiarid region, constituting an aggravating factor with regard to the rational allocation of water to crops (SANTOS et al, 2009)

Summary

Introduction

The semiarid region of Brazil has a recognized potential of being a major producer of tropical fruits. There is very few research data related to these coefficients, especially in the semiarid region, constituting an aggravating factor with regard to the rational allocation of water to crops (SANTOS et al, 2009). It becomes necessary, in irrigated plantations, the conduction of a proper management of irrigation, meeting the needs of the crop, to allow the manifestation of their productive potential, which basically consists in defining as precisely as possible how much to irrigate, which depends crucially on the knowledge of evapotranspiration (FREITAS et al, 2007)

Objectives

Methods

Results

Conclusion