Prof. Lajos Helyes did his PhD in Horticultural Science at Hungarian Academy of Science, Hungary.He is currently working as Vice-rector for science at Szent Istvan University and the Director of Horticultural Institute, Szent Istvan University. He is an elected member of Production of vegetables for processing ISHS working group1998 and also the member of the International Society for Horticultural Sciences. His main research areas: Effect of water supply, irrigation on yield quantity and quality of vegetable crops (tomato, sweet pepper, eggplant, broccoli, carrot, onion). Irrigation scheduling and timing. His research activities have been supplemented - parallel with nutritional and international research expectations - with the evaluation of determinants of vegetable quality and organoleptically important components (special regards to biologically active components). The number of scientific publications: 186, independent citations: 817.
In tomato fruit cells the lycopene molecule is an intermediate of the biosynthesis of ß-carotene. Tomato fruit ripening is a complex, genetically programmed process that culminates in dramatic changes in texture, colour, flavour, and aroma of the fruit flesh. The tomato has climacteric respiration. The biosynthesis of lycopene is affected by abiotic (temperature, light, water- and nutrition supply, etc.) and biotic (mycorrhization, grafting, genotype) conditions and the context of these factors, the growing methods (forcing, open-field growing etc.), date of harvest, maturity stage, also significant factors. In the mature green stage the fruit contained small amount of lycopene which was hardly detectable. In subsequent maturity stages, lycopene content of the fruits increased. Almost half of the total lycopene content is synthesized and accumulated in the deep red stage. Lycopene synthesis by various tomato cultivars was completely inhibited above 32°C. We found significant differences (p=0.001) between shaded (SF) and non-shaded (NS) fruit surface temperatures and so the lycopene content as well. Solar exposure caused overheating above the optimal temperature of lycopene synthesis, resulted less lycopene content of fruits than shading by canopy. We have found strong negative correlations between the lycopene concentration and optimum water supply. In fact, many experiments have found evidence that small fruits contain more lycopene than larger ones. We did not find a positive relationship between the concentration of lycopene and mycorrhization. But for example, according to other works tomato plants inoculated with AMF increase lycopene and β-carotene content in fruits compared to those without inoculation. Contrary to the results of other researchers, grafting in our experiment caused a significant (P<0.05) decrease in lycopene content of fruits in all the three years. According to the experimental results significantly higher lycopene content was observed in glasshouse-grown tomatoes than in field-grown. Under the same environmental conditions, processing tomatoes had significantly higher lycopene concentration (P<0.05), compared to indeterminate fresh market round type.