Variation for Nitrogen Use Efficiency Traits in Wheat Under Contrasting Nitrogen Treatments in South-Eastern Europe

Abstract

Wheat cultivars differ in their response to nitrogen (N) fertilizer, both in terms of its uptake and utilization. Characterizing this variation is an important step in improving the N use efficiency (NUE) of future cultivars while maximizing production (yield) potential. In this study, we compared the agronomic performance of 48 diverse wheat cultivars released between 1936 and 2016 at low and high N input levels in field conditions to assess the relationship between NUE and its components. Agronomic trait values were significantly lower in the low N treatment, and the cultivars tested showed a significant variation for all traits (apart from the N remobilization efficiency), indicating that response is genotype-dependent, although significant genotype × environment effects were also observed. Overall, we show a varietal improvement in NUE over time of 0.33 and 0.30% year–1 at low and high N, respectively, and propose that this is driven predominantly by varietal selection for increased yield. More complete understanding of the components of these improvements will inform future targeted breeding and selection strategies to support a reduction in fertilizer use while maintaining productivity.

Improved Bread and Durum Wheat Cultivars Showed Contrasting Performances in N-Efficiency and N-Responsiveness

“…Similar to the present findings, an overall positive relationship between grain yield and N levels among wheat cultivars was reported by Nehe et al [8], Gaju et al [14], Mansour et al [16], and Ivić et al [41]. Nehe et al [8] stated that the growth in grain yield under high N compared with low N conditions was 1.49 t•ha −1 (+29.6%) and 1.43 t•ha −1 (+26.7%) in 2014 and 2016, respectively, with an average rise across years of 1.46 t•ha −1 (+28.1%).…”

“…Similarly, Gaju et al [14] also reported an overall 10.1% increase in grain yield among the 15 wheat cultivars under high N (743.6 g•m −2 ) compared with low N (665.6 g•m −2 ) conditions. A similar 10% increase in grain yield under high compared with low N conditions in southeastern European environments was also reported in a panel of 48 winter wheat cultivars by Ivić et al [41]. Belete et al [5] and Tyagi et al [42] also observed significant grain yield difference among wheat cultivars and N condition, showing that the cultivars also contrasted in terms of responsiveness to N supply, which is similar to the results of the current study.…”

“…According to Nehe et al [8], Ranjan et al [11], and Gaju et al [14], and consistent with our data, genetic variations in NUE among wheat cultivars was more strongly linked to NUpE than NUtE under both high N and low N conditions. e significant effects of genotype, N, and their interaction on NUpE were reported in a number of works (e.g., [11,14,15,41]). In agreement with the current results, Fatholahi et al [15] reported that NUpE of all types of wheat, which ranged from 1.72 to 7.14 kg•N in plant kg −1 N applied, was decreased with increase in the N supply.…”

“…In agreement with the present study, Fatholahi et al [15] stated that NUtE of majority of the wheat cultivars did not indicate a particular trend. A number of studies (e.g., [8,11,14,16,41]) documented a significant and positive linear relationship between NUtE and grain yield of wheat cultivars at low N and high N, which shows the importance of these traits in varietal response to N fertilization recommendations. Overall increased NUtE of wheat under low N (33.9 and 44.6 kg DM•kg −1 N) compared with high N (26.3 and 44.6 kg DM kg•N −1 ) conditions were reported by Nehe et al [8] and Gaju et al [14], respectively.…”

Genetic Control of Efficient Nitrogen Use for High Yield and Grain Protein Concentration in Wheat: A Review

“…Understanding historical trends in N use-related traits during wheat breeding is important to design strategy in improving the NUE of future varieties while maximizing yield potential and GPC [13]. Although wheat breeding was in most cases not targeted to improve NUE [7], significant genetic gains have been observed for N use-related traits around the world (Table 1).…”