ISHS Acta Horticulturae 797: International Workshop on Greenhouse Environmental Control and Crop Production in Semi-Arid Regions
EFFECTS OF VAPOUR PRESSURE DEFICIT AND RADIATION ON THE TRANSPIRATION RATE OF A GREENHOUSE SWEET PEPPER CROP |
| Authors: | J.C. Gázquez, J.C. López, E. Baeza, J.J. Pérez-Parra, M.D. Fernández, A. Baille, M. González-Real |
| Keywords: | irrigation control, ventilation, fan ventilation, fog-system, whitening, lysimeter |
| Abstract:
The effects of air vapour pressure deficit (VPD) and radiation reduction by whitening on the transpiration rates of a greenhouse sweet pepper crop (transplanted in July) under a semi-arid climate (Almería, south-eastern Spain) were studied. Measurements were carried out during ontogeny in three analogue multi-span curved greenhouses: (i) without air VPD control and no whitening ii) with a fog-system operating when air VPD was higher than 1.5 kPa and iii) without air VPD control and with whitening (about 30% reduction in greenhouse solar radiation transmission). Leaf transpiration vs. inside solar radiation, air VPD and leaf area index were studied and analysed. A model has been developed (multiple regression analysis), based on the simplified Penman-Monteith formula, between the measured transpiration rate and the radiative and advective components, equation: λE = A f1(LAI)Rg + B f2(LAI)VPD, which for different conditions of air VPD and inside radiation, gave a good prediction of the hourly water consumption. This simplified transpiration model can be used to manage irrigation with different conditions of VPD and incoming radiation. | |
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