Effect of climatic conditions and fertilization on structure of grain yield of winter wheat (Triticum aestivum L.) | Vplyv klimatických podmienok a hnojenia na štruktúru úrody zrna pšenice letnej f. ozimnej (Triticum aestivum L.)

Winter wheat variety Viginta was evaluated in long-term stationary experiment in Research - breeding station Vígľaš-Pstruša on twelve fertilization variants with increasing nitrogen doses (0 - 40 - 80 - 120 - 150 kg per ha) combined with P and K fertilizers (60 kg P2O5 and 60 kg K2O) in four years (2001/02 to 2004/05). Grain yield, one thousand grain yied and grain number per square m were evaluated. Variability of grain yield was conditioned by years as well as fertilizations. Average grain yields varied among four years in the same range (4.56-7.41 tons per ha) as among twelve fertilization variants (4.66-7.41 tons per ha). Precipitation and temperature during grain filling determined differences among years in grain yield. Reasons of low grain yield in 2003 (4.56 tons per ha) were low precipitations and high temperatures in June and on the contrary high grain yields in 2004 and 2005 were conditioned by average precipitations and below average temperature during grain filling period. Fertilization only by PK fertilizers increased grain yields compared to permanently unfertilized variant by 16%. The highest grain yield was at N 80 kg and 60 kg P2O5 (155.7%). Increasing of N fertilizers above 80 kg N for grain yield was not effective. Among fertilization variants N versus N plus PK fertilization no significant differences were found. On the level N fertilization 80 kg N per ha more effective was combination N + P, at which the highest grain yield was raised, than combinations N + K or N + PK. Number of grains had more effect on the grain yield variability than one thousand grain yield. Increasing N doses increased number of grains per area, however decreased one thousand grain yield. Lack of sources from continuous assimilation or translocation was cause of low one thousand grain yield at higher grain number on the variants with higher intensity of fertilization.