**4. Aknowledgments**

This work was conducted within the framework of ''Progetto interregionale OLVIVA'' funded by Programma Interregionale - ''Sviluppo rurale - Innovazione e Ricerca'' D.M. n. 25279 of 23/12/03'' and of "Progetto Strategico PS59" funded by Regione Puglia, Italy .
