Tomatoes may have a great impact in the prevention of some types of cancer. This protective effect has been attributed to lycopene. The biosynthesis of lycopene is affected by environmental conditions. If the temperature of the fruits exceeds 30 • C, the synthesis of lycopene is inhibited. Strong direct radiation on fruits (∼2990 µmol m −2 s −1 for 1.5-4 h) is harmful. In 2002, we investigated the effect of temperature and photosynthetically active radiation (PAR) on lycopene content. Fruit samples were harvested three times during the growing phase. The average lycopene content of harvested fruits, picked on 18 June 2002, reached 64.9 mg kg −1 of fresh tomato. The fruits gathered on 25 June 2002 contained on average only 35.5 mg of lycopene per kilogram. The average lycopene content from the third harvest (on 9 July 2002) was 68.9 mg kg −1 . The values of PAR varied between 150 and 415 µmol m −2 s −1 , so they did not exceed the critical value. The average temperature preceding the second harvest was the highest (28-32 • C) and the maximum temperature ranged between 40 and 43 • C. This prolonged, extremely high temperature may have caused the low lycopene level in the second harvest. The lycopene content of six ripeness stages, from green to deep red stage, was measured in 2002 and 2003. The accumulation of lycopene accelerates from the pink stage and there is a high correlation (R 2 = 0.92) between lycopene content and colour values (a * /b * ). The higher the ratio of a * /b * , the higher was the lycopene content.

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Tomato is one of the most important sources of lycopene. The effect of water supply was investigated on lycopene content of Daniela F 1 tomato harvested in greenhouse. The lycopene content of fruits supplied with 50% of optimal water intake was higher (86.5 mg kg -1 f.w.) than that of fruits supplied with 100% of optimal water intake (62.5 mg kg -1 f.w.). Significantly higher lycopene content was observed in tomato harvested in greenhouse (83.0 mg kg -1 f.w.) than in field (59.2 mg kg -1 f.w.), at every harvesting time. The highest concentration of lycopene was detected in cherry tomato (77.4 mg kg -1 f.w.) while Daniela F 1 with 59.2 mg lycopene per kg and Delfine F 1 with 69.6 mg lycopene per kg had significantly lower level (under field conditions).

Tomato (Lycopersicon esculentum) fruit is an important source of antioxidants, which are important in the prevention of many cancer types and cardiovascular diseases. In ripe tomato fruit, one of the most significant antioxidant compounds is lycopene. In this study, effects of the cultivars and the environmental conditions on the lycopene content were investigated. Temperature effect was characterized by calculating growing degree-day (GDD). Relationships among lycopene, total polyphenols, organic acid, and total antioxidant status (TAS) were analyzed. A variation of more than 30% was found among the lycopene levels of five processing tomato cultivars. Lycopene content ranged from 79.7 to 155.0 mg·kg–1 fresh weight. There was a significant difference between the lycopene concentrations of fruit harvested at two different dates. The values were higher at the second harvest, probably due to the cooler weather conditions preceding that harvest. Total polyphenols correlated strongly with TAS but the other antioxidants did not have any relationship to TAS. GDD were strongly and positively correlated with hydroxymethylfurfural content in fresh tomatoes.