The experiment was performed in a 140 m2 multi-span greenhouse covered with plastic film. The greenhouse was located at IRTA Centre of Cabrils (Cabrils, Barcelona, Spain, 41°25′ N, 2°23′ E, altitude 85 m).
Tomato (Solanum lycopersicum L.) seedlings obtained from a commercial nursery were cultivated in 60-L perlite bags. The particle size of perlite was between 0.1 and 5 mm. Each bag contained three plants. The experiment lasted for five months (from March to July 2008). Plants were fertilized by fertigation and the nutrient solution was applied with a drip irrigation system. Pollinating wasps (Bombus terrestris L.) were introduced at 50% opened flowers of the first truss.