Acknowledgments
This work was financed by the ‘Ministerio de Ciencia y
Tecnología’ INIA-RTA04-007. The authors thank Albert
Fontquerna, Mª José Bautista, Agustí Quintana and Albert
Rossell for their technical assistance.We thank the ‘Departament
d'Universitats, Recerca i Societat de la Informació of Generalitat de
Catalunya’ and ‘Fons Social Europeu’ for the grant awarded to
Núria Panella-Riera to finance her doctoral studies at IRTA.