N-STATUS OF POT PLANTS AS EVALUATED BY MEASUREMENT OF SUBSTRATE AND PLANT SAP NITRATE
N-Status of Begonia - Elatior - Hybr., Cyclamen pers. and Saintpaulia ion. supplied by fertigation could not be determined by substrate analysis. Optimum growth as well as N-deficiency were observed at 10–15 mg N/1 substrate. Nitrate content in petiole press sap reflected N-supply of cyclamen and saintpaulias. For begonias, however, nitrate content of petiole sap didn't vary significantly with N-supply because the nitrate concentration was below 200 ppm. This could be related to a high nitrate reductase activity in the root.
The nitrate concentration in petiole press sap was hardly influenced by the NO3 : NH4 ratio of the fertigation.
Schenk, M.K. (1988). N-STATUS OF POT PLANTS AS EVALUATED BY MEASUREMENT OF SUBSTRATE AND PLANT SAP NITRATE. Acta Hortic. 221, 253-260