CHANGES OF NUTRIENT VALUES IN HIDROPHONIC TOMATO GROWING SYSTEM PUBLISHED

Tibor Terbe - Barbara Schmidt-Szantner tterbe@gmail.com
As consumer demands change, beside early availability of fruits and vegetables, high content value becomes more and more expected. Health-enhancing impacts of tomato are, among others, attributed to lycopene, thus varieties containing higher amount of lycopene are sought-after in production. Outdoor plants obtain the necessary amount of carbon dioxide from the atmosphere that has a CO2 concentration of approximately 300 ppm (0.03 vol%). In tightly sealed greenhouses the required amount of carbon dioxide can be provided by ventilation. However, the issue of CO2 fertilisation has been emerged in the 1950s in connection with vegetable forcing. This practice has become an integral part of forcing in numerous countries during the past 20 to 25 years. In our experiment we tried to learn how the growing conditions of vegetable forcing, CO2 content in particular, influence content value, with special attention paid to lycopene content. In 2017 we have examined the content values of Aruba F1 vine tomato grown in the greenhouse of St István University Galambos educational facility. We used the data of plant monitoring (leaf area etc.). The climate computer controlling the greenhouse made it possible to record and assess different sets of data such as outer and inner temperature, insolation, CO2 level etc. One of the outstanding characteristics of Aruba F1 tomato is its deep red colour. Based on the measurements it is due to its high content value – especially to lycopene. However, content values showed considerable fluctuations during the examined growing period of 2017. The difference between the highest and lowest recorded values was approximately 50%. Remarkable distinction was also observed between the highest peak in August and the lowest value in September. It can only partly be explained by the decreasing temperature and insolation, since samples from May had higher content values despite the same amount of total insolation and lower weekly mean temperatures. By examining the 60-day-long ripening period it can be concluded that the considerable (-39%) decrease of temperature implied the reduction of leaf area (-30%). Therefore, it can be presumed that these two changes together led to the notable alteration of content values. The overall conclusion is that, beside the variety, environmental conditions dominantly influence the amount of lycopene even in case of soilless cultivation. Although these environmental factors can, in certain extent, be adjusted in greenhouses, plants react in a sensitive way to changes occurring in light conditions, temperature and CO2 level. These reactions affect content values of the plants, including the amount of lycopene that is an important quality indicator.
hydroponics, tomato, temperature, insolation, artificial regulation of carbon dioxide, content value, lycopene
Biology applied in Agriculture
Presentation: poster

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