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The effect of fertilization with different forms of nitrogen on yield and nitrate metabolism in leaves of greenhouse lettuce. II. Effect of growth regulators

J. Myczkowski*, S. Rożek*, W. Sady**

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

The selected indices of the metabolism of lettuce plants, fertilized with nitrate and the ammonium and urea forms of nitrogen using growth regulators, were investigated.

The ammonium and urea forms of nitrogen decreased the activity of nitrate and nitrite reductase, as well as the content of nitrate and nitrite, and increased the content of water-soluble saccharides and dry weight in the leaves and the lettuce yield as compared with the nitrate form.

The results testify to the usefulness of reduced forms of nitrogen for improvement of the biological value of lettuce grown with the nutrient film technique.

The growth regulators (GA3 + kinetin) caused a decrease in nitrite and an increase in water-soluble saccharides in the leaves as well as in the lettuce yield, especially when the urea form was applied for fertilization.

Myczkowski J., Rożek S., Sady W., 1991. The effect of fertilization with different forms of nitrogen on yield and nitrate metabolism in leaves of greenhouse lettuce. II. Effect of growth regulators. Folia Horticulturae III/1: 13-25.