EVALUATION OF A SIMPLE SAP NITRATE TEST FOR BLANCHING CELERY (APIUM GRAVEOLENS)
Periole sap nitrate concentration was measured with the use of Merckoquant strips. As nitrate contents of plant sap exceed the colour maximum of 500 pmm, the time from wetting to colour maximum was used as an index. For use under practical conditions, a clear insight is needed in the distribution of nitrate in the plant and in the variability in nitrate content among neighbouring plants grown under similar conditions. With data obtained in a phytotron and in field experiments, a quick sap test is proposed for blanching celery (Apium graveolus).