Abstract

The objective of this work was to evaluate petiole extract as an indicator of the nutritional status of the table grapevine 'Red Globe', using the relationship between the contents of N, P and K in petiole extract and the ones of blades and roots. The study was done between December 2006 and February 2007. Three fertilization trials with N, P2O5 and K2O in one‑year‑old plants, grown in containers, were established. Nitrate, phosphate and potassium concentration were evaluated in the petiole extract, and nitrogen, phosphorus and potassium were determined in blades and roots. Petiole extract analysis was more sensitive than blade and root analysis to determine the nitrate status and nitrogen diagnosis, whereas blade analysis shows the plant response to increasing doses of phosphorus and potassium better than petiole extract and root analysis. Petiole extract analysis can reveal antagonism between nutrients under high doses of fertilization.