TRANSPIRATION OF GLASSHOUSE ROSE CROPS: EVALUATION OF REGRESSION MODELS

R. Baas, E. van Rijssel
Regression models of transpiration (T) based on global radiation inside the greenhouse (G), with or without energy input from heating pipes (Eh) and/or vapor pressure deficit (VPD) were parameterized. Therefore, data on T, G, temperatures from air, canopy and heating pipes, and VPD from both a lysimeter experiment and from a cut rose grower were analyzed. Based on daily integrals, all T models showed good fits due to the dominant effect of global radiation G (solar + supplementary radiation) inside the greenhouse on T. Similar G-T relations on high-light and low-light days indicated identical effects of solar radiation and radiation from supplementary light on T. For both data sets, similar regression coefficients of 0.3 l/MJ were obtained with models including G and VPDair, G and Eh, or G and a constant intercept. Including the difference between saturated pressure at leaf temperature and air vapor pressure (VPDleaf-air) did not improve the regression models. G accounted for 74% of latent heat transfer. The contribution of heating underneath the canopy on T was investigated by switching off the heating on days during the winter period, and was on average 13% or 0.2 l/m².day for an extra energy input by heating pipes of 3 MJ/m².day. Therefore, the efficiency of sub-canopy heating was smaller than 0.07 l/MJ, less than 23% of the efficiency of global radiation.
Baas, R. and van Rijssel, E. (2006). TRANSPIRATION OF GLASSHOUSE ROSE CROPS: EVALUATION OF REGRESSION MODELS. Acta Hortic. 718, 547-556
DOI: 10.17660/ActaHortic.2006.718.64
https://doi.org/10.17660/ActaHortic.2006.718.64
global radiation, heating, lysimeter, supplementary lighting
English

Acta Horticulturae