COMPARISON BETWEEN ANALYTICAL RESULTS OF PLANT SAP ANALYSIS AND THE DRY ASHING METHOD FOR TOMATO PLANTS CULTURED HYDROPONICALLY

Tomato plants (Lycopersicon esculentum Mill cv. Momotaro) were culture d in nutrient solutions of varying concentrations or of varying nitrat e (NO,) levels. The leaf blades and the main petioles including rachis were collected from the mixture of three successive leaves below each fruit truss at two growth stages. Comparisons were made between the n utrient concentration in the leaf blade and the petiole determined by plant sap analysis, and that in the leaf blade determined by the dry a shing method. Closely correlated relationships were found to exist bet ween the phosphorus (P), calcium (Ca), and magnesium (Mg) concentratio ns in the leaf blade and the petiole determined by plant sap analysis, and those in the leaf blade determined by the dry ashing method at tw o growth stages. For the concentration of potassium (K), there was no correlation between results of plant sap analysis and those determined by the dry ashing method at either growth stage.