1. Dep. of Agricultural Biotechnology Univ. of Padua viale dell'Università 16 35020 Legnaro PD Italy
2. Dep. of Agricultural and Environmental Sci. Univ. of Udine Via delle Scienze 208 33100 Udine Italy
3. CRA‐Experimental Institute for Crop Sci. viale Caduti in Guerra 133 44100 Modena Italy
4. CRA‐Experimental Institute for Industrial Crops viale Amendola 82 45100 Rovigo Italy
5. USDA‐ARS, 494D Plant and Soil Sci. Bldg., Michigan State Univ. East Lansing MI 48824‐1325
6. USDA‐ARS Crop Research Laboratory 1701 Center Avenue Fort Collins CO 80526