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Fertilizing cultivable plants is an effective way of improving yield quantity and quality. The studies conducted in the years 2008–2009 were aimed at determining the relationship between the kind of nitrogen fertilizer, manner of its application, as well as the dose of calcium carbonate and the plant unit weight, as well as chemical composition of spinach beet, grown in glasshouse in the spring period. Nitrogen was applied in the form of ammonium sulphate and urea in a localized form (N-deposit) and in the form of solution. Calcium was administered in the form of calcium carbonate in the doses of 5 and 15 g · dm-3 of substratum. The length of leaves, plant unit weight and selected parameters of beet leaf utility value were assessed. The substratum was also analyzed after plant harvest. The highest unit weight of plants was obtained with the application of ammonium sulfate in the form of a solution with a lower calcium carbonate dose, compared to the remaining combinations. The examined spinach beet plants were distinguished by high contents of dry matter, protein, total nitrogen, potassium, calcium and magnesium The chemical composition of leaves was significantly differentiated, depending on the examined factors. The contents of nitrates in the leaf dry matter ranged from 0.26 to 0.45%, depending on the kind of nitrogen fertilizer and manner of its application. The applied nitrogen fertilization to a small extent influenced the concentration of nitrates in beet leaves. More nitrates were contained in plants fed by a higher dose of calcium carbonate, compared to the plants which were given a lower dose of CaCO3. The highest content of vitamin C and the lowest share of nitrates in leaf dry matter were obtained with the application of urea in the form of deposit with a lower dose of calcium carbonate.
In a field experiment conducted in 2004-2006, the influence of the harvest term on yield and crop quality of cv. Lukullus Spinach beet was examined. Seeds were sown to the field in the second decade of April and after thinning left at a spacing 45x25 cm. First harvest of leaves was conducted in mid-July and 2 subsequent harvests occurred in two week’s intervals. The content of dry matter, vitamin C, phosphorus, potassium, calcium and magnesium were determined in samples of leaf blades and petioles. The results proved that the yield of Spinach beet increased from 42.46 t.ha-1 in the first term of harvest to 72.04 t.ha-1 and 105.61 t.ha-1 in the subsequent terms. Delayed harvest date appeared to be beneficial for the content of dry matter and vitamin C, and resulted in the decrement of the amounts of potassium and magnesium as well as in the accumulation of nitrates in plants. Plants harvested later also contained a lower level of phosphorus in leaf blades. Generally, higher amounts of dry matter, potassium and magnesium were observed in leaf blades, while petioles contained more phosphorus, calcium and nitrates.
The examinations were aimed at determining the dependence between form and rate of applied nitrogen fertilizer vs. yield and chemical composition of leaves of Swiss chard cultivated in greenhouse in spring. Nitrogen was applied in a form of urea, potassium nitrate, and ammonium nitrate at three amounts: 0.2; 0.4; 0.6 g N·dm⁻³ of substrate. Following items were assessed: yield, nutrients contents, as well as chemical analyses of substrate after plant harvest were made. Increase of nitrogen rate in objects with potassium nitrate and ammonium nitrate resulted in the decrease of fresh matter yield, while in objects with urea, the yield remained at constant level. The highest yield of above ground parts (356 g·plant⁻¹) was achieved by fertilizing the plants with the lowest nitrogen rate (as ammonium nitrate). Contents of nitrates in leaf dry matter was within the range of 0.59–1.27% depending on nitrogen rate and form. The highest nitrate levels were found when potassium nitrate was applied as fertilizer, whereas the lowest – when applying ammonium nitrate; however, regardless the fertilizer type, higher rates caused the increase of nitrate contents. Studies revealed that at increasing nitrogen concentration in a substrate, level of vitamin C also increased. Contents of N, P, K, Ca, and Mg in Swiss chard’s leaves depended on nitrogen fertilizer type. Comparison of studied factors influence on potassium concentration in plants indicated that increasing nitrogen rates in objects with urea and ammonium nitrate was accompanied by the decrease of this element content. An inverse dependence was recorded in objects with potassium nitrate, where content of potassium in Swiss chard’s leaves increased along with the nitrogen level increase. Application of 0.2 g N· dm⁻³ substrate appeared to be the most profitable in spring cultivation of Swiss chard, because the largest yields of fresh matter and the lowest share of nitrates in dry matter of studied plant were found.
Swiss chard is recognized as valuable leafy vegetable species with short growing period suitable for cultivation as forecrop and aftercrop in crop rotation .Till now is still a minor crop in Poland and there are not existing any data describing the response of this species to nitrogen fertilization and the effect of this nutrient on plant composition. In a field experiment conducted in 2004–2006, the influence of nitrogen fertilization applied as a single or split dose in the amounts of 50, 100, 100 + 50, 150, 150 + 50 and 200 kg∙ha-1 on yield and crop quality of Swiss chard was examined. Seeds of Lukullus cv. were sown directly into the field in the half of April in spacing 45 × 25 cm, and single harvest of leaf rosettes was conducted on 8–10 July. In separate samples of leaf blades and petioles there was evaluated the content of dry matter, vitamin C, sugars, total N, nitrates, P, K, Ca, and Mg. Results of the study indicate that the increment of N dose from 50 to 100 kg∙ha-1 had positive effects on Swiss chard yield but the efficiency of higher nitrogen doses was rather small and not significant. Heavy nitrogen fertilization caused the increment of total N and nitrates in both edible parts and magnesium in leaf petioles, while reduction the sugar content in leaf blades. On the average blades contained higher amounts of dry matter, sugars, total N and Mg, while petioles – calcium and nitrates.
Zawartość azotanów w buraku liściowym zależała od części użytkowej i wynosiła w blaszkach liściowych 1422-2723 mg NaNO3 / 1000 g i w ogonkach liściowych 2429-4198 mg NaNO3 / 1000 g świeżej masy, osiągając swoje maksimum w 3 zbiorze. Nie stwierdzono obecności azotynów. Proces technologiczny mrożenia i przechowywanie mrożonek w temp. -20°C i -30°C nie powodowały znaczących zmian w poziomie tych związków, z wyjątkiem blanszowania, które obniżało zawartość azotanów o 10-29% w zależności od części liścia.
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