|Authors: ||D. Hadad, V. Lukyanov, S. Cohen, Z. Gilad, E. Zipilevitz, A. Meir, D. Silverman, U. Adler, Y. Esquira, J. Tanny|
|Keywords: ||temperature, radiation, relative humidity, air velocity, Penman-Monteith|
The area of crops grown in protected environments, like greenhouses and screenhouses, is constantly increasing worldwide.
However, in the agricultural practice, most growers do not consider the difference in cover type in their irrigation management.
The objective was to study the effect of roof cover type, either plastic or porous screen, on microclimate, Penman-Monteith evapotranspiration (ET) models, and water use efficiency, to improve irrigation management.
A field study was carried out during the growing season 2016-2017 in two otherwise identical structures in which a pepper crop was grown.
One roof was a plastic sheet (hereafter denoted as the greenhouse) and the other an insect-proof 17-mesh screen (screenhouse). In both houses, microclimate was measured simultaneously above the canopy.
Outside meteorological conditions were measured by a nearby external weather station.
Evapotranspiration was estimated using 8 different versions of the Penman-Monteith model.
Transpiration was measured using the heat-pulse technique.
In four neighbouring houses, an irrigation trial was conducted with three treatments.
Linear regressions were derived between internal and external meteorological conditions, with R2 values between 0.13 and 0.99. Higher R2 values were obtained for the screenhouse.
Linear regressions between measured and modelled ET were derived with R2 between 0.48 and 0.84. Transpiration measurements were in high agreement with a PM model based on internal meteorological conditions and a boundary-layer resistance.
Water use efficiency for the irrigation treatment based on this model was larger by 31% (screenhouse) and 38% (greenhouse) than that obtained using regional recommended irrigation.
Download Adobe Acrobat Reader (free software to read PDF files)