H. Vitoshkin,
M. Sacks,
V. Haslavsky

An experimental analysis was combined with numerical simulations to examine microclimate parameters and ventilation methods in a hydroponic greenhouse. The aim was to provide uniform airflow circulation in order to prevent tipburn injury in lettuce cultivation during the hot summer period. Experiments were conducted in a commercial hydroponic greenhouse located in Ben-Shemen, Israel. Two ventilation configurations have been evaluated and both demonstrated similar results. Factors such as greenhouse temperature and humidity, and leaf temperature were monitored. The results show that horizontal air circulation forced by industrial fans over the crop with a velocity of 2 m s^‑1 is capable of reducing tipburn occurrence to 30% in both plots using front or side ventilation. In following, three-dimensional flow in the greenhouse has been modeled using ANSYS Software to evaluate the airflow patterns and velocities inside and around the two-level unit. The results illustrate that among several ventilation configuration, the optimal configuration includes two fans above each canopy level providing satisfying air circulation with velocity of 2 m s^‑1 in order to prevent plant disorders, such as tipburn.