The Effect of Mean Daily Temperature and Relative Humidity on Pollen, Fruit Set and Yield of Tomato Grown in Commercial Protected Cultivation

The research trial was carried out in the Mediterranean region where high summer temperatures have been proved to have a detrimental effect on the delicate tomato fruitset process. The flower to fruit set process was simultaneously monitored in fogged and unfogged shelters during the three-month Mediterranean summer season. Comparisons of pollen quality, fruit set rates and fruit yield revealed that mean daily temperatures of 25–26 °C are the upper limit for proper fruit set and fruit yield for tomatoes grown in protected cultivation during the hot Mediterranean summer period. A moderate reduction of 1–1.5 °C in mean daily temperatures together with the increased RH (relative humidity) from 50% to 70% during day time improved the pollen grain’s viability. Suggestions concerning more efficient controls on the fogging system considering those findings are discussed.