1. Institute of Field and Vegetable Crops, M. Gorkog 30, 21000 Novi Sad, Yugoslavia
2. Corresponding author. E-mail: mladenov@ifvcns.ns.ac.yu Phone: 381 21 411 888. Fax. 381 21 621 212.
3. Agricultural Research Institute, Center for Small Grains, 34000 Kragujevac, Yugoslavia.