Source of nitrogen affects the yield and quality of spinach cultivars grown for autumn harvest
2014
Krężel, Jan | Kołota, Eugeniusz
Spinach can be grown for early harvest in the spring mainly for fresh market supply or for autumn harvest, used on a large scale for processing. The experiment was carried out in 2007–2009, and its aim was the determination of the effect of different nitrogen fertilizers (ammonium nitrate, calcium nitrate, ammonium sulfate, and Entec-26) on yielding and nutritional value of seven spinach cultivars (Greta F ₁, Industra, Markiza F ₁, Matador, Olbrzym Zimowy, Rembrandt F ₁, and Spokane F ₁), cultivated in foil tunnel for autumn harvest. The obtained data indicated that the highest marketable yield was provided by application of Entec-26 fertilizer. Similar yielding was also recorded for plants fertilized with ammonium or calcium nitrate, whereas significantly lower one resulted from fertilization with ammonium sulfate. Olbrzym Zimowy appeared to be the best – yielding cultivar, although Spokane F ₁ and Rembrandt F ₁ gave the results at comparative level. The application of ammonium sulfate and calcium nitrate contributed the least to the accumulation of nitrates in spinach leaves, whereas comparison of cultivars revealed the lowest nitrates accumulation in Matador. Furthermore, this cultivar also contained the highest amount of vitamin C, which was particularly apparent when Entec-26 fertilization was applied. The use of Entec-26 was associated with the highest accumulation of potassium and the lowest content of magnesium. The highest levels of potassium were found in Industra, magnesium – in Olbrzym Zimowy, and Greta F ₁ featured the highest content of calcium. Ammonium sulfate, assuring the best quality of the crop expressed by a high content of vitamin C and lower nitrates accumulation than other sources of nitrogen, can be recommended for the use in practice.
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