Abstract

This study evaluates five methods to estimate crop evapotranspiration in greenhouse conditions. It compares their performance in relation to the evapotranspiration directly determined from water balance measurements (ET(lys)) in an irrigated lettuce (Lactuca sativa L.) crop during 9 weeks. Daily values of the reference evapotranspiration (ETo) from Class A pan (CAP), Piche atmometers (ATM), Andersson evaporimeters (ANE), FAO-Radiation (FRE) and FAO-Penman-Monteith (PME) equations were compared. The methods showed similar temporal variations but at different ranges as follows: ANE < CAP < FRE < PME < ATM. Furthemore, ETo had a clear correlation with solar radiation. Crop coefficients (Kc = ET(lys)/ETo) varied somewhat amongst the methods, but trends were identified for two periods: in the first week, the overall mean Kc was 0.3 (+/- 0.1) and in weeks 2 to 9 on average 0.6 (+/- 0.3). The greenhouse values of Kc were lower than those generally adopted for lettuce in field conditions. In terms of irrigation design, crop evapotranspiration can be estimated by the methods in this study, on the condition that the appropriate crop coefficients are applied. The fact that ANE showed values closest to those of ETlys, along with cost and management convenience, makes it an advantageous alternative as compared to the other methods.

Keywords

evapotranspiration; greenhouse; lettuce; lysimeter; Lactuca sativa

Published in

Chilean Journal of Agricultural Research
2009, Volume: 69, number: 1, pages: 60-70
Publisher: INST INVESTIGACIONES AGROPECUARIAS

SLU Authors

• Messing, Ingmar

  • Department of Soil Sciences, Swedish University of Agricultural Sciences
    

• Joel, Abraham

  • Department of Soil Sciences, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Horticulture
Food Science
Environmental Sciences related to Agriculture and Land-use


Permanent link to this page (URI)

https://res.slu.se/id/publ/61662