Progress in Accumulation and Translocation of Nitrogen in Winter Wheat Cultivars Released in the Years 1921–2003

Ten winter wheat cultivars released in the years 1921–2003 in Slovakia were evaluated in pot experiment in 4 variants of N fertilization and in 2 terms of harvest (heading — a, maturity — m). Biomass N concentration at heading, grain N concentration (Ng), straw N concentration (Nv), and biomass N concentration at maturity were determined. N uptake and characteristics of N translocation, accumulation in grain and utilization were estimated. The year of cultivar release (YCR) was in relationships with nitrogen translocation efficiency (NTRE) (r = 0.720++) and with decreasing N% in vegetative biomass during grain filling (RNT) (r = −0.614). Strong correlation between YCR and N uptake in grain (r = 0.796), YCR and N harvest index (NHI) (r = 0.816++), and YCR and N utilization for grain (NUTg) (r = 0.877++) indicated that the modern cultivars more intensive accumulated N in grain and utilised N for grain than old ones. YCR was in negative correlation with N uptake in biomass at heading (r = −0.790++), N utilization for biomass (r = −0.678+) and with ratio Ng to Nv (relative N accumulation RNA) (r = −0.710+). Modern cultivars, in spite of their higher grain N uptake (NUP), lower N concentration in straw, higher N accumulation in grain (NHI) and higher efficiency of N translocation (NTRE) and (RNT), had lower N grain concentration than old cultivars. At the same or lower total N uptake they had considerably higher grain yield and therefore between Ng and NUTg was strong negative correlation (r = −0.977++). This is a result of the unilateral selection on grain yield. Selection should be concentrated not only on increasing of N uptake efficiency, but also on increasing of total N uptake by increasing of biomass N concentration. RNT and RNA are also recommended for selection on increasing of N grain concentration. Hypothetic models of cultivars with different NUP, NUTg and different relationships between NUTg and Ng were discussed.