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The effect of fertilization with nitrate and urea forms of nitrogen on quality and storage ability of lettuce grown in a foil tunnel. I. Content of certain nutritive compounds

Stanisław Rożek, Maria Leja, Jan Myczkowski, Anna Mareczek

Department of Plant Physiology
Faculty of Horticulture, Agricultural University
29 Listopada 54, 31-425 Kraków, Poland

The results are presented of a two-year investigation concerning the effect of nitrate nitrogen (N-NO3) and urea nitrogen (N-NH2) forms, applied in fertilization of lettuce cultivated in a foil tunnel on changes in certain quality indices of the yield and their changes during the storage of heads at low (5°C) and high (20°C) temperatures.

The applied form of nitrogen did not affect the yield of freshly harvested lettuce, the level of dry matter, soluble sugars, and starch or the content of total protein and ascorbic acid. A lower level of free amino acids was found in the samples of the Prado cultivar treated with urea in comparison with those treated with nitrate. In the case of the cultivar Oresto an opposite effect was observed. A significantly lower ATP level was determined in the leaves of Oresto treated with urea in relation to samples treated with nitrate.

A more significant variability in the content of particular compounds was observed between cultivars than between treatments. The effect of the form of applied nitrogen was more distinct during storage of the lettuce leaves both at room temperature (20°C) and in a cold chamber (5°C).

Rożek S., Leja M., Myczkowski J., Mareczek A., 1995. The effect of fertilization with nitrate and urea forms of nitrogen on quality and storage ability of lettuce grown in a foil tunnel. I. Content of certain nutritive compounds. Folia Horticulturae 7/1: 91-105.