CONTRIBUTION OF PLANT-BREEDING TO LONG-TERM AGRONOMIC TRAIT CHANGES IN MAIZE HYBRIDS FAO-100 AND FAO-200

The purpose of this study was to assess improvements in performance of maize hybrids during a 20-year period. Data on FAO 100 and 200 hybrid s, released by the former Yugoslay Committee for Releasing Varieties, were utilized. For FAO 100 hybrids group, yield increased 0.0015 Mg ha (-1) year(-1), but was not significant. Breeding resulted in a signifi cant decrease in days to silking. In the FAO 200 group, yield increase d on the average 0.046 Mg ha(-1) year(-1). The genetic gain was not si gnificant. A performance index, based on yield and several other trait s, increased significantly during the period for both groups of hybrid s, but the increase due to breeding was significant for the FAO 200 hy brids only.