Folia Horticulturae

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Effect of light and growth regulators on the circadian rhytmicity of nitrate reductase and nitrite reductase activities in greenhouse lettuce leaves

Stanisław Rożek, Renata Wojciechowska

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

Circadian rhytmicity of nitrate reductase and nitrite reductase in two greenhouse lettuce cultivars (Columbus and Alka) has been definitely confirmed. Nitrate reductase is most active at the noon hours and in the case of the Alka cultivar this process has double intensity. This supports the opinion that nitrate reductase activity is conditioned genetically.

Great discrepancies in the reduction rate of nitrites appeared in GA3 and kinetin treated plants, while an increase in enzyme activity in the morning hours and its maximum activity during the afternoon were observed.

These observations permit the conclusion that nitrite reductase in greenhouse lettuce is strongly affected by growth regulators.

Rożek S., Wojciechowska R., 1990. Effect of light and growth regulators on the circadian rhytmicity of nitrate reductase and nitrite reductase activities in greenhouse lettuce leaves. Folia Horticulturae II/1: 53-64.