MULTINUTRIENT DIAGNOSIS OF NITROGEN STATUS IN PLANTS

The nitrogen (N) status of conifer seedlings, onion, and potato was di agnosed using the Critical Value Approach and the Compositional Nutrie nt Diagnosis (CND). The multinutrient CND N indices (IN) accounted for the phosphorus (P) and potassium (K) concentrations in tissues. For c onifer seedlings, a linear-plateau relationship with well defined defi ciency and excess zones was shown between dry matter yields and IN, wh ile the yield-N response curve was distorted. The yield-IN relationshi p for onion and potato was improved as compared to the yield-N curve. Correlation coefficients with yields were higher for IN values than fo r raw concentration values. Critical IN values were -1.8 for conifers, -0.8 for potato, and -0.7 for onion.