Intergovernmental Panel on Climate Change (IPCC) announced that

this global average temperature rise can cause significant changes in the natural ecosystems, such as higher frequency of drought and increases in heavy rainfall. Many researchers have been studying this rise in the temperature and reported its effect as a serious threat to global agricultural production (Sato et al., 2006; Kamel et al., 2010). In the latest years, all over the world, an increase in planting of various crops has been noticed, including tomato, in high temperature regions or environments, either in the field or greenhouse. The stress caused by high temperatures in these environments causes a reduction in the number of pollen grains in susceptible tomato genotypes, reducing fruit set (Firon et al., 2006). The temperature considered optimal for the production of tomato ranges from 21 to 28°C during the day and from 15 to 20°C during the night. Considering that the night temperature is also considered a limiting factor to good fruit set in tomato (Filgueira, 2008). Traits such as pollen grains viability, osmotic pressure, production of fruits per plant and fruit set are suggested by some authors (Abdul-Baki & Stommel, 1995; Hanson et al., 2002; Saeed et al., 2007) for evaluation and selection of heat tolerant genotypes. For this, the use of experiments in field and greenhouse still stands as the most appropriate SANTOS LS; MELO RA; SANTOS PR; CARVALHO FILHO JLS; MENEZES D. 2014. Tolerance to high temperature in F5 inbred lines of tomato. Hor