1. USDA-ARS, Plant Science and Entomology Research Unit; Dep. of Agronomy; 2001 Throckmorton Plant Science Center, Kansas State Univ. Manhattan KS 66506
2. Pioneer Hi-Bred Intl.; P.O. Box 328 Hamel IL 62046
3. USDA-ARS, Plant Physiology and Genetics Research Unit; Dep. of Crop Sciences; 1101W. Peabody Dr., Univ. of Illinois Urbana IL 61801
4. CIMMYT Applied Biotechnology Center; Lisboa 27, Apdo Postal 6-641 06600 Mexico DF Mexico