Water consumption of pepper grown in an insect proof screenhouse

Insect-exclusion screenhouses have become popular among growers because they reduce the need for pesticide application, cost much less than greenhouses and are believed to have a relatively minor effect on the microclimate of the crop. Although the total area of screenhouses around the world is steadily increasing, there is minimal data on the water consumption of crops grown within such structures. The present study is focused on measurements of crop water consumption and evapotranspiration in a 50-mesh commercial screenhouse cultivated with sweet pepper. The heat pulse technique was used to measure stem water flow rate and the eddy correlation method was utilized to measure crop evapotranspiration above the canopy. The two independent techniques had results that were in agreement. Indirect measurements implied that soil evaporation was negligible in the screenhouse under study. Daily water consumption was 1.8 - 2.1 mm during August 2001 and 1.4 - 1.6 mm during September 2001. The measured water consumption is about 1/3 of the potential evapotranspiration calculated for a pepper crop grown in the open field. As of yet, it is impossible to provide specific recommendations for irrigation in screenhouses; this requires further experiments including the monitoring of plant water status and total screenhouse water balance.