Abstract
The effect of a previous heat shock (HS) on growth and development of different tomato (Lycopersicon esculentum Mill.) cultivars under defined heat stress (HSt) conditions were investigated. Plants were grown under two day/night temperature regimes (26/20 ºC and 37/27 ºC, respectively) in growth chambers at the Department of Vegetable Crops, Institute for Horticultural Sciences, Faculty of Agriculture and Horticulture, Humboldt University of Berlin. The experiments were conducted twice and were set up in a randomized design with five replicates. The reproductive processes in tomato were more sensitive to high temperatures than the vegetative ones. The number of pollen grains, number of fruits and fruit fresh masses produced by the heat tolerant cultivars were higher than those of the heat sensitive cultivars. However, HS pretreatments had no positive effects on tomato growth and development.