ISHS Acta Horticulturae 659: VII International Symposium on Protected Cultivation in Mild Winter Climates: Production, Pest Management and Global Competition
INFLUENCE OF AN EXTERNAL GREENHOUSE MOBILE SHADING ON TOMATO CROP TRANSPIRATION |
| Authors: | E. Medrano, P. Lorenzo, M.C. Sánchez-Guerrero, M.L. García, I. Caparrós, M. Giménez |
| Keywords: | Irrigation control, soilless culture, lysimeter. |
| Abstract:
The effect of an external mobile shading on the transpiration rate of a tomato crop (vs. Boludo) was studied in multispan greenhouses during spring. Measurements were conducted during ontogeny in two greenhouses (i) with an external mobile shading activated when the air greenhouse temperature was higher than 27°C and (ii) without shading. Transpiration rate was determined by weighing plants with an electronic balance. The use of external mobile shading reduced canopy transpiration rate, reaching at solar midday values of 350 J m-2 s-1 in the reference greenhouse and 150 J m-2 s-1 in the shaded greenhouse, with a reduction of the incident solar radiation from 700 to 200 W m-2 and the air VPD from 2.5 to 1.25 kPa. The response of the leaf transpiration to the incident radiation was lower in the shaded greenhouse because the on-off status of the shade screen around noon generated a lower VPD for similar radiation values. A multiple regression analysis, based on the simplified Penman-Monteith formula, was established between the measured transpiration rate and the radiative and advective components. Either with or without shading, the model had a good prediction of the hourly water consumption, using the same multiple regression coefficients. | |
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