1. International Maize and Wheat Improvement Center (CIMMYT); El Batán Mexico
2. INRA; UMR759 LEPSE; F-34060 Montpellier France
3. Agroscope; Forage Crop Breeding Group; 8046 Zürich Switzerland
4. Unitat de Fisiologia Vegetal; Facultat de Biologia; Universitat de Barcelona; Barcelona Spain