1. Dep. of Crop Sciences; Univ. of Illinois; 1102 S. Goodwin Ave. Urbana IL 61801
2. Institute of Agronomy and Plant Breeding II; Justus Liebig Univ.; Heinrich-Buff-Ring 26-32, D-35392 Giessen Germany
3. Dep. of Agronomy; Purdue Univ.; 915 W. State Street West Lafayette IN 47907