IMPACT OF WHITEWASH COATED POLYETHYLENE FILM COVER ON THE GREENHOUSE

Whitewash is a sustainable technique in Mediterranean greenhouses. where high radiation during spring and summer generates microclimate of high temperature and low Vapour Pressure Deficit (VPD). The aim ofthe present research was to study the effect of polyethylene film covering whitewashed and control on global radiation, VPD and air temperature. This study was conducted in a polyethylene multitunnel greenhouse without crop in the University of Almeria (Spain). The covering transmission coefficient in the greenhouse is not constant along the spectrum. Under whitewashed condition, greenhouse presented a reduction of the air temperature and global radiation of 32 and 41 per cent and an increase of 46 per cent in the VPD. Comparing with the external condition, the average reduction of radiation was 54.7 per cent and 29.6 per cent, the average increment ofVPD was -2.63 kPa and -1.42 kPa and the average diminution of temperature was 10.8 °C and 7.4 °C in the control greenhouse and with whitewash, respectively