Energy efficiency in agriculture. Showcase and alternatives for wheat production in Portugal. - Baptista, F; Silva, LL; de Visser, C; Go?aszewski, J; Meyer-Aurich, A; Briassoulis, D; Mikkola, H; Murcho, D; Marques, C; Marques da Silva, JR; Rosado, M (University of Life Sciences, Lublin, Poland and University of Évora, Portugal, 2014)