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Due to the climate change and increasing prices for fossil fuels, a new climate strategy for closed greenhouses was developed at the Humboldt-Universität zu Berlin and compared to a conventional climate strategy. One of the main objectives of this study was to investigate the effects of climate conditions in a closed greenhouse on plant growth, fruit yield and quality characteristics of tomatoes. The first results of the start-up phase showed, that the total yield of marketable fruits harvested in the closed greenhouse without CO2 enrichment was significantly increased by 8.6% compared to the reference greenhouse. Compared to the conventional climate strategy, non-marketable fruits yield was significantly decreased by the influence of the closed operation mode. The results of this study have also shown that the climate conditions in the closed greenhouse increased the leaf area per plant, influenced the formation of fruit sets positively, and significantly affected health-promoting properties of tomatoes. It was demonstrated that the contents of lycopene and ß-carotene of tomatoes were increased significantly in the closed greenhouse. The increase of carotenoids also significantly increased the antioxidant activity by 30% compared to the tomatoes harvested in the reference greenhouse. http://www.actahort.org/books/952/952_65.htm
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... In tomato, yield was also increased as a result of better product quality and a reduction in the share of unmarketable waste products that were too small or affected by BER (Dannehl et al., 2012). Moreover, closed greenhouses produced tomato fruits containing larger amounts of lycopene, β-carotene, phenolics, and ascorbic acid, with better sensory attributes in terms of sweetness, juiciness, and firmness (Dannehl et al., 2014). ...
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... In tomato, yield was also increased as a result of better product quality and a reduction in the share of unmarketable waste products that were too small or affected by BER (Dannehl et al., 2012). Moreover, closed greenhouses produced tomato fruits containing larger amounts of lycopene, β-carotene, phenolics, and ascorbic acid, with better sensory attributes in terms of sweetness, juiciness, and firmness (Dannehl et al., 2014). ...
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Antioxidants are believed to be important in the prevention of diseases such as cancer and cardiovascular disease. Lycopene is one of the main antioxidants to be found in fresh tomatoes and processed tomato products. The lycopene content also accounts for the redness of the fruit, which is one of the main qualities for which industry and consumers now look. Other carotenes (such as β-carotene), vitamin C, vitamin E and various phenolic compounds are also thought to be health-promoting factors with antioxidant properties. Since the antioxidant content of tomatoes may depend on genetic factors, the choice of variety cultivated may affect the results at harvest. To be able to control the antioxidant content of tomatoes at the field level when growing a given variety, it is necessary to know the effects of both environmental factors and the agricultural techniques used. Temperatures below 12 °C strongly inhibit lycopene biosynthesis and temperatures above 32 °C stop this process altogether. The effects of the temperature on the synthesis of other antioxidants have not yet been properly assessed. The effects of light have been studied more thoroughly, apart from those on vitamin E. The effects of water availability, mineral nutrients (nitrogen, phosphorus, potassium and calcium) and plant growth regulators have been studied, but results are sometimes contradictory and the data often incomplete. During the ripening period, lycopene content of tomatoes increases sharply from the pink stage onwards, but no sufficient attempts have been made so far to assess the changes in the other antioxidants present in the fruit. This paper reviews the present state of the art. Copyright © 2003 Society of Chemical Industry
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summary‘Tiny Tim’ tomato plants were exposed to five CO2 treatments (375 (ambient), 450, 525, 600 or 675 μmol mol−1) in combination with 03 (0 or 80 nmol mol−1. Biomass was evaluated following 3,5,7 and 13 wk exposure. Biomass following 13 wk exposure also included weekly harvests of mature tomato fruit beginning week 8. Carbon dioxide enrichment significantly enhanced total vegetative plant d. wt at each harvest, as well as cumulative yield of mature fruit, whereas O3 significantly suppressed total vegetative plant d. wt at each harvest and reduced total cumulative fruit yield. The magnitude of these changes varied with the development of tomato from early growth to mature fruit yield. Carbon dioxide enrichment reduced the detrimental effects of O3 on total vegetative plant d. wt of tomato following 3, 5, 7 and 13 wk exposure. Final mature fruit yield was 24% higher under enriched GO2 treatments than in ambient CO2. Ozone suppressed final yield by 31%, following exposure to 80 nmol mol−1 O2, when compared with exposure to charcoal-filtered (CF) air. The impacts of both CO2 and O3 on yield were, however, dependent upon the presence or absence of the other gas. In the absence of O3, yields were very similar for the ambient and elevated CO2 treatments, but in the presence of O3, yields under ambient CO2 were greatly suppressed whereas yields under elevated CO3 were similar to those in the absence of O3. Thus, enriched CO2 ameliorated most of the suppressive effect of O3 on yield of mature fruit.
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BACKGROUND: A greenhouse experiment was performed to study the effect of cumulative air temperature and photosynthetically active radiation (PAR) on tomato quality. Tomato plants were subjected to two different shading treatments causing a 30 and 50% reduction in incoming PAR respectively (plants were exposed to 70 and 50% of incoming PAR respectively). Control plants (exposed to 100% of incoming PAR) were also included in the experiment. The experiment was carried out under unheated greenhouse conditions. To minimise the dependence of temperature on PAR, only a small area inside a large greenhouse was shaded, thereby allowing air currents to homogenise temperature all over the enclosure. Parameters of tomato quality were correlated with cumulative temperature (Tcum) and cumulative PAR (PARcum) for a period of 45 days before harvest. RESULTS:Tcum was strongly correlated with firmness, electrical conductivity, soluble solids content and total phenolic compounds and weakly correlated with pH, dry weight, titratable acidity and vitamin C content. PARcum was only weakly correlated with firmness, dry weight, soluble solids content and total phenolic compounds. CONCLUSION:Tcum has a stronger influence on tomato quality than PARcum. Growers could obtain tomatoes of similar quality under lower PAR than that provided by natural sunlight. Copyright