THE EFFECT OF FERTILIZATION ON THE YIELD OF SUNFLOWER HYBRIDS IN DIFFERENT CROPYEARS ON CHERNOZEM SOIL

As the number of hybrids requiring new and more intensive cultivation methods is growing, the importance of fertilization has significantly increased in sunflower production; the determination of the exact fertilizer need as a hybrid specific cultivation method is becoming more important. In 1999 the capability for nutrient uptake of hybrids showed great differences, the control yield ranged between 3300-3600 kg ha(-1). In the case of Arena hybrids, the yield enhancing effect of fertilization was significant. Yield maximum was achieved at 90 kg ha(-1) N+PK dose by the examined hybrid. However, the fertilizer response curve of Pixel was distinct and decreased from N-30+PK fertilizer dose. In the crop year of 2000 the control hybrids were significantly different. From among the hybrids, the fertilizer response curve of Alexandra and Arena PR reached the highest yield-level, however, the response on increasing fertilizer doses was much lower in 2000 than in the previous year. In 2001, the yield surplus attained with fertilization exceeded 1200 kg ha(-1), the average yield increase was 910 kg ha(-1). These values lead to the conclusion that the fertilization effect was significant. In 2008, hybrid NX 65001 reached the highest absolute surplus yield (1047 kg ha(-1)). At N-30+PK dose each hybrid reached the maximum yield. The depressive effect of nutrient increase had most significant effect on hybrid NK Neoma, in the case of which the yield decrease started already at N-60+PK fertilizer dose. To summarize the results of the four years, we can conclude that on chernozem soil in different years the nitrogen dose belonging to the yield maximum changes in the range of 30 to 90 kg/ha N+PK depending upon the hybrid, higher fertilizer dose was applied in drier years.