Percorrer por autor "Antoniadis, Vasileios"
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- Chemical composition and antioxidant activity of Cichorium spinosum L. leaves in relation to developmental stagePublication . Petropoulos, Spyridon Α.; Fernandes, Ângela; Antoniadis, Vasileios; Ntatsi, Georgia; Barros, Lillian; Ferreira, Isabel C.F.R.In the present study, chemical composition and bioactivity of Cichorium spinosum leaves were examined at different growth stages for optimum harvest stage and end-use assessment. Total fresh weight and number of leaves were higher at 4th growth stage; however, at this stage the end-use is not indicated for raw consumption but mostly for pickled or dried products. Regarding chemical composition, the highest content of tocopherols and minerals was observed in the 1st growth stage, whereas sugars content was the highest in 3rd and 4th growth stage. Polyunsaturated fatty acids content was the highest during the first two growth stages, whereas antioxidant activity, phenolic acids and total phenolic compounds content in the 3rd stage. In conclusion, the results of this study indicate that chemical composition of C. spinosum is highly depended on development stage, and harvest stage should be considered for alternative uses of end-products with high bioactivity.
- Effect of ammonium fertilizer on growth and quality of Cichorium spinosum plantsPublication . Anesti, Stavroula; Fasoli, Konstantina; Petropoulos, Spyridon Α.; Ntatsi, Georgia; Antoniadis, Vasileios; Ferreira, Isabel C.F.R.In the present study, the effect of ammonium fertilizer rate on plant growth and quality of Cichorium spinosum L. was examined. Five fertilizer treatments were applied regarding the ammonium nitrogen percentage of total nitrogen, namely (1) 14%, (2) 24%, (3) 34%, (4) 43%, and (5) 53% of total nitrogen applied in the form of ammonium nitrogen. All the treatments received the same total nitrogen rate. Seeds of C. spinosum were sown in seed trays containing peat, and young seedlings were transplanted in 2L pots containing peat and perlite in a ratio 1:1. Plants were harvested twice during growing period and when rosettes reached the marketable size. On the harvest days, plant features regarding plant development (the number of leaves, the fresh and dry weight of leaves, and rosette diameter), as well as quality mineral composition, SPAD index of leaves) were recorded. From the results it is suggested that fertilizer composition had a significant effect on plant growth and quality. In particular, fresh weight for both harvests, as well total fresh weight were higher in treatments 4 and 5, where 43 and 53% of the total nitrogen was applied as ammonium nitrogen. Dry weight did not differ significantly in the first harvest, while in the second harvest treatment 1 had the lowest dry weight. Diameter and number of leaves were the lowest in treatments 2 and 3, respectively, while significant differences were also observed between treatments regarding the quality features.
- Effect of storage on quality features of local onion landrace ‘Vatikiotiko’Publication . Petropoulos, Spyridon Α.; Fernandes, Ângela; Barros, Lillian; Barreira, João C.M.; Ntatsi, Georgia; Antoniadis, Vasileios‘Vatikiotiko’ is a Greek landrace of Allium cepa L. of the Liliaceae family, cultivated only in the region of Vatika, in Lakonia prefecture as a short day onion. The dry bulbs are a quality product highly sought after in Greek market, since this is the earliest onion that comes out during Spring. However, so far the production is limited and the potential of this landrace is not fully developed. In the present study we examined the effect of storage at two temperatures (23±1 and 5±1°C) and 60-70% RH (relative humidity) on marketability and quality features of dry bulbs of ‘Vatikiotiko’ landrace and ‘Sivan F1’ which is also cultivated in the specific region. The experiments were carried out at the University of Thessaly, Greece during the period 2014-2015. The quality features that were recorded during storage included fresh weight loss, bulb firmness, antioxidants and sugar’s composition. The measurements were taken at regular intervals and the storage was completed when either bulbs had not marketable quality or sprouting occurred. So far the results have shown that ‘Vatikiotiko’ onion can be stored for 7 months at both temperatures, whereas at 5±1°C storage could be prolonged for almost 8 months without significant marketability and quality loss. Similarly, ‘Sivan F1’ sprouting occurred after 5 and 6 months at 23±1 and 5±1°C, respectively. Therefore, the fact that ‘Vatikiotiko’ landrace is a storage onion allows for further valorization in order to increase total production and yield, since the stored product could cover the market needs that arise throughout the year, whereas breeding is needed in order to minimize the genetic variability of the landrace and increase uniformity of the final product.
- The impact of fertilization regime on the crop performance and chemical composition of potato (Solanum tuberosum L.) cultivated in central GreecePublication . Petropoulos, Spyridon Α.; Fernandes, Ângela; Polyzos, Nikolaos; Antoniadis, Vasileios; Barros, Lillian; Ferreira, Isabel C.F.R.Potato cultivation is quite demanding in inorganic nutrients and adequate fertilization is a key factor for maximizing yield and producing tubers of high quality. In the present study, a field experiment was carried out to evaluate the effect of various forms of fertilization on crop performance and the nutritional value and chemical composition of two potato varieties (cv. Spunta and cv. Kennebec). For this purpose, five different fertilizer treatments were applied namely: control (C), standard fertilizer (T1), standard fertilizer + zeolite (T2), manure (T3) and slow release nitrogen fertilizer (T4). According to the results, it was observed that slow release treatment (T4) achieved the highest yield for both varieties, while the control treatment presented significantly lower yield compared to the studied fertilization regimes. The dry matter of leaves and shoots was higher in T1 treatment for cv. Kennebec and in T2 and T4 treatments for cv. Spunta, whereas the control treatment presented the highest dry matter content in tubers for cv. Kennebec and T2 and T3 treatments for cv. Spunta. A significant effect of the fertilization regime was also observed on the nutritional value of tubers and more specifically the protein, ash and fat content was increased by treatments T1 and T4, while carbohydrate content was also increased by T3 and T4 treatments for both varieties. Similarly, the total sugars, organic acids, β-carotene and lycopene content was increased in T3 treatment for the Spunta variety, while the antioxidant capacity showed a varied response depending on the fertilizer regime and the tested variety. In conclusion, the fertilization regime has a significant effect not only on the tuber yield but also on the quality of the final product and should be considered as an effective tool to increase the added value of potato crop.
- Long-term storage effect on chemical composition, nutritional value and quality of Greek onion landrace “Vatikiotiko”Publication . Petropoulos, Spyridon Α.; Ntatsi, Georgia; Fernandes, Ângela; Barros, Lillian; Barreira, João C.M.; Ferreira, Isabel C.F.R.; Antoniadis, VasileiosThe effect of storage at two temperatures (5±1 and 25±1 °C and 60-70±5% RH for both temperatures) on marketability and quality features of dry bulbs of local landrace "Vatikiotiko", "Sivan F1", "Red Cross F1" and "Creamgold" was examined. During storage measurements for fresh and dry weight of bulbs, tunic and flesh color, bulb firmness, nutritional value and mineral composition were taken at regular intervals. Storage concluded when either bulbs lost marketable quality or sprouting occurred. "Vatikiotiko" onion can be stored for at least 7months at 25±1 °C, whereas at 5±1 °C storage could be prolonged without significant marketability and quality loss. The fact that "Vatikiotiko" landrace can be considered a "storage" onion has to be capitalized in order to increase total production and yield, since storage could cover the market needs that arise throughout the year.
- Nutrient solution composition and growing season affect yield and chemical composition of Cichorium spinosum plantsPublication . Petropoulos, Spyridon Α.; Fernandes, Ângela; Karkanis, Anestis; Antoniadis, Vasileios; Barros, Lillian; Ferreira, Isabel C.F.R.Nitrogen fertilizer form may affect quality and yield of leafy vegetables. In the present study, the effect of ammonium nitrogen rates on yield and chemical composition of Cichorium spinosum L. was examined. Five fertilizer treatments with different amounts of ammonium nitrogen (F1: 14%, F2: 24%, F3: 34%, F4: 43% and F5: 53% NH 4 -0N of total N) were applied. Fertilizer treatments had a significant effect on both plant fresh weight and chemical composition, depending on growing period and harvest stage. For both harvests of the 1st growing period, yield was higher in treatments F4 (43% NH 4 -N) and F5 (53% NH 4 -N), whereas in the 2nd growing period yield was higher for treatments F1, F2 and F3. Moreover, the highest content of total phenolics were recorded in the 2nd growing period. Antioxidant properties were also affected by fertilization treatments and growing periods, with antioxidant potency being higher in the 2nd growing period and for treatments F1 and F2. According to the results of the present study, nitrogen fertilizer form should be considered together with growing period and harvest stage as a useful means towards increasing the quality of the final product without compromising total yield.
- The optimization of nitrogen fertilization regulates crop performance and quality of processing tomato (Solanum lycopersicum L. cv. Heinz 3402)Publication . Petropoulos, Spyridon Α.; Xyrafis, Eustratios; Polyzos, Nikolaos; Antoniadis, Vasileios; Fernandes, Ângela; Barros, Lillian; Ferreira, Isabel C.F.R.In this study, we evaluated the e ect of various fertilization regimes on processing tomato (Solanum lycopersicum L. cv. Heinz 3402) yield and quality by applying the following treatments: (i) control (C), (ii) conventional fertilizer (21-0-0, N-P-K) (CF), (iii) slow release nitrogen fertilizer 46-0-0 (SR), (iv) conventional fertilizer (21-0-0, N-P-K) + Zeolite (CFZ), and v) composted sheep manure (M). The results of the study showed that the SR and CFZ treatments resulted in the highest fruit yield per hectare compared to the rest of the fertilizer and the control treatments. Fruit firmness was higher for the treatments C,Mand SR, while color parameters (chroma and hue angle) were higher for the C and M treatments, respectively. Moreover, the total soluble solids content (TSS; Brix) was higher when manure (M) was applied. In terms of chemical composition, the total and individual tocopherols and sugars were the highest for the M and C treatments, respectively, whereas the oxalic, malic and total organic acid contents were the highest for the CFZ treatment. Moreover, the tested treatments showed a varied response in di erent antioxidant assays, although the M treatment exhibited a high antioxidant capacity in most of the assays, except for the -carotene/linoleate assay. The carotenoid and chlorophyll contents were the highest for the control treatment. The main detected fatty acid was linoleic acid, followed by palmitic, oleic and -linolenic acid, while the CFZ treatment had the highest content of polyunsaturated fatty acids (PUFA) due to its high content of linoleic acid. In conclusion, although the application of fertilizers increased yield, the quality parameters and chemical composition showed a varied response to the fertilization regime, especially the TSS content and juice pH and electric conductivity (EC), which are significant for the marketability of the final product.
- The effect of long-term storage on quality of “vatikiotiko” onionPublication . Petropoulos, Spyridon Α.; Fernandes, Ângela; Barros, Lillian; Barreira, João C.M.; Ferreira, Isabel C.F.R.; Ntatsi, Georgia; Antoniadis, VasileiosIn the present study the effect of long-term storage on “Vatikiotiko” onion in comparison to the “Sivan F1” hybrid. Dry bulbs of both genotypes were stored in two temperatures (5 and 25 °C) and 60-70% RH. During and after storage, weight loss (%), antioxidant activity, total soluble solids content, mineral composition and organic acid content were measured. According to the results, it was found that “Vatikiotiko” onion is suitable for long-term storage (at least 7 months) at both temperatures (5 and 25 °C), without significant weight loss and sprouting incidence, whereas for “Sivan F1” sprouting was observed after 5 and 6 months of storage at 25 and 5 °C, respectively. Total soluble solids content was not affected significantly during storage in both genotypes, whereas flavonoids content increased significantly only in “Sivan F1”. The rest of antioxidant activity parameters had similar responses in both genotypes and storage temperatures and either increased (β-carotene, reducing power) or decreased (TBARS). Regarding mineral composition, K content increased and Ca and Mg content decreased in both genotypes, whereas for the other mineral elements the responses differed according to the genotype. Organic acids content increased in “Sivan F1” during storage, whereas no significant changes were observed in “Vatikiotiko” onion. In conclusion, ‘Vatikiotiko’ landrace has a high potential for long-term storage, at either 5 or 25 °C.
- The effect of nutrient solution composition on development of Cichorium spinosum plantsPublication . Kolovou, Panagiota; Antoniadis, Vasileios; Karkanis, Anestis; Ferreira, Isabel C.F.R.; Petropoulos, Spyridon Α.In the present study, the effect of nutrient solution composition on plant growth and quality of Cichorium spinosum L. was examined. Five fertilizer treatments were applied through irrigation water differing in the nitrate: ammonium nitrogen ratio of total nitrogen, namely (1) 100:0, (2) 75:25, (3) 50:50, (4) 25:75, 5) 0:100 NO3:NH4, while an extra treatment (6) with total nitrogen only in urea form was applied. All the treatments received the same amount of fertilizer units (20-20-20 mg L-1 of N, P and K, respectively). Plants were grown in 2 L pots containing peat (Klassman-Deilmann KTS2) and harvested three times during the growing period, and when they reached marketable size. At each harvest day, plant development was assessed (number, fresh and dry weight of leaves, and rosette diameter). The results suggest that nitrogen form has a significant effect on plant growth and yield of C. spinosum plants. In particular, fresh weight and number of leaves, and rosette diameter were significantly increased when ratio of nitrate: ammonium nitrogen was 75:25 or 0:100, especially in the 1st harvest, while in the 3rd harvest treatment 100:0 showed the best results. However, this did not affect total fresh weight and number of leaves which were higher for treatments 100:0 and 75:25, respectively. Therefore, higher ammonium nitrogen rates seem to be beneficial for plant development only during the early stages, while at later growth stages nitrate nitrogen has better results. In any case, ureic nitrogen is not suggested since it has severe effects on plant development, probably due to toxicity issues.
- Yield and chemical composition of Cichorium spinosum L. in relation to nitrogen ratePublication . Ioannou, Andri; Petropoulos, Spyridon Α.; Fernandes, Ângela; Karkanis, Anestis; Antoniadis, Vasileios; Barros, Lillian; Ferreira, Isabel C.F.R.In the present study, the effect of nitrogen (N) application rate on plant growth and quality of Cichorium spinosum L. was examined. Four nitrogen rates were applied, namely: a) Control (no added N), b) 200 mg L-1 of total N, c) 400 mg L-1 of total N, and d) 600 mg L-1 of total N. Plant growth (rosette diameter, number of leaves, SPAD index, and fresh and dry weight) and chemical composition of leaves (sugars, organic and fatty acids, tocopherols, minerals and nitrates content) were recorded. Fresh weight increased up to 400 mg L-1, whereas dry weight was not affected by N rate. Plants treated with N formed larger rosettes and more leaves comparing to control treatment, except for the rate of 600 mg L-1 where number of leaves did not differ from control. SPAD index was higher at the rate of 600 mg L-1. The application of N resulted in higher content of sugars, whereas tocopherols showed a significant decrease. In conclusion, the application of nitrogen rates up to 400 mg L-1 is suggested for high yields without compromising the quality of the final product.