Folia Horticulturae

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The effect of some factors on the content of nitrate and nitrite in lettuce leaves grown with the nutrient film technique. I. The effect of light and growth regulators

S. Rożek*, J. Myczkowski*, W. Sady**, T. Wojtaszek**

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

In order to eliminate excess nitrate and nitrite from greenhouse lettuce leaves, an attempt at using growth regulators (GA3, kinetin, and GA3/kinetin mixture) was made in conjunction with the prolongation of light period to 16 hrs per day. The reduction of nitrate content on lettuce harvest day was achieved with the use of GA3/kinetin mixture and, when employing the 16-hr light period, also under the influence of kinetin alone. In all combinations employed, the growth regulators decreased the nitrite content on harvest day, irrespective of lighting conditions. Growth regulators combined with the effect of light stimulated the growth of fresh weight in lettuce heads and increased soluble-saccharide content in leaves.

Rożek S., Myczkowski J., Sady W., Wojtaszek T., 1989. The effect of some factors on the content of nitrate and nitrite in lettuce leaves grown with the nutrient film technique. I. The effect of light and growth regulators. Folia Horticulturae I/1: 31-43.