Response of winter wheat cultivars to N fertilization in grain yield and its components | Reakcia odrôd pšenice letnej f. ozimnej na N hnojenie v úrode zrna a v úrodotvorných znakoch

During two years 2004/05 and 2005/06 in the field experiment the set of 12 winter wheat cultivars originated from different regions of Europe was evaluated in the response to N fertilization in grain yield and its components. The experiment was established by alpha design method in 3 variants of N fertilization (0 – 100 – 200 kg N per ha). Besides grain yield from the parcel yield components were estimated from the plant sample. Years, N fertilization and cultivars had significant effect on the variability of all evaluated traits except HI, did not effect by years. Even though the cultivars originated from the geographically different regions only for single grain weight (SGW) interaction year × cultivar was found. For grain yield, SGW and HI significant interaction cultivar × N fertilization was found. The most cultivars reached the maximal grain yield at the rate 100 kg N per ha except for cultivars Evropa 90, Pobeda and Axis that had maximal yield at the highest N rate, even though cultivars Pobeda and Zlatka had under average grain yield. By the slopes of joint regression model and average yield, cultivars for low input system were detected (Sonata, Renan and Malyska, Vanda). The differences in grain yield among cultivars were the most explained by the variability of grain number per area (GN) (r = 0.703++) and ear number per area (r = 0.600++), while the variability of plant height, vegetative biomass were less and eventually for SGW none important. High negative correlation between GN and SGW was conditioned by genetically, when cultivars with high GN had low SGW (r = –0.810++) and by N fertilization, which increased GN, but decreased SGW. Increasing of N fertilization increased the sources for grain yield (biomass production, stand height, ear number) and potential sink capacity expressed by GN, but decreased effectiveness of distribution and translocation of assimilates in consequence of SGW and HI were decreased. In the paper selective advantage GN versus SGW is discussed.