MICRONUTRIENT COMPOSITION OF XYLEM SAP AND NEEDLES AS A RESULT OF P-FERTILIZATION IN MARITIME PINE

Xylem sap and foliar compositions (P, Cu, Zn, Mn) were examined over 4 months in control and P-fertilized maritime pine in a 7-year-old plan tation. The absorption of copper, zinc, and boron appears to be reduce d by phosphate fertilization. Manganese concentrations are positively related to P-supply increase. Foliar analysis and sap provides the sam e type of information in terms of antagonism or synergism between elem ents but the response to treatment is more often significant with sap throughout the seasons and is completely non-existent on a single clas sical autumn diagnosis with foliar concentration (i.e. Zn and Cu). In consequence foliar analysis is not sensitive enough for copper or zinc deficiency diagnoses in young plantations where nutritional growth di sorders appear in a short period of spring, and xylem chemistry appear s to be a convenient tool in monitoring micronutrient disorders in pin e plantations.