Folia Horticulturae

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The effect of nitrate and urea forms of nitrogen on the metabolism of tomato plants grown by the nutrient film technique

S. Rożek*, W. Sady**, J. Myczkowski*

**Department of Plant Physiology
**Institute of Vegetables and Ornamental Plants
**Faculty of Horticulture, Agricultural University
**29 Listopada 54, 31-425 Kraków, Poland

The effect of the nitrate and urea forms of nitrogen and of a mixture of these two forms on the activity of nitrate reductase, as well as on the content on nitrates, nitrites, and saccharides and K, Ca, and Mg, were investigated in the leaves of a greenhouse tomato Ostona F1 cultivar grown by the nutrient film technique.

In separate nutrients a rapid change of urea into the nitrate form was observed, which may be confirmed by a high level of nitrates in the leaves of plants grown even on the nutrient containing nitrogen only in the urea form. The highest activity of nitrate reductase and also the content of nitrates were determined in the leaves of plants grown on the nutrient containing 75% nitrogen in the amide form and 25% of that in the nitrate one. The nutrients used in the experiment, differentiated in respect of the fraction of particular nitrogen forms, also affected the content of nitrites, saccharides, K, Ca, and Mg in the tomato leaves.

Rożek S., Sady W., Myczkowski J., 1990. The effect of nitrate and urea form of nitrogen on the metabolism of tomato plants grown by the nutrient film technique. Folia Horticulturae II/2: 13-27.