1. Agricultural & Biological Engineering Dep.; Univ. of Florida; Gainesville FL 32611
2. LEPSE, Univ. Montpellier, INRA, Montpellier SupAgro; 34060 Montpellier France
3. Institute of Crop Science and Resource Conservation INRES; Univ. of Bonn; Bonn 53115 Germany
4. CSIRO Agriculture and Food; 203 Tor St. Toowoomba QLD 4053 Australia
5. Prairie and Boreal Plain Ecozone; Science and Technology Branch; Agriculture and Agri-Food Canada/Agriculture et Agroalimentaire Canada; PO Box 3000, 5403-1 Ave. South Lethbridge AB T1J 4B1 Canada
6. CIMMYT Int. Adpo; Mexico City 06600 Mexico
7. Univ. of Adelaide; Adelaide SA Australia
8. GDEC, INRA, UCA; 63000 Clermont-Ferrand France
9. Dep. of Agronomy and Horticulture; Univ. of Nebraska; 1875 N. 38th St. Lincoln NE 68583-0915