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.
Highlights
Climate change, competition for land, limited natural resources, and the co-occurrence of abiotic and biotic stresses all threaten global wheat production
The difference (% of high N (HN)) for production traits, including grain yield (GY), Grain protein content (GPC), GNY, and HI, were all significantly higher at HN compared to low N (LN), whereas N use efficiency (NUE), N utilization efficiency (NUtE), NUtE_PROT, NUE_PROT, and BPE were reduced at HN
For PH, NHI, and BPE, the lowest mean values were recorded in Osijek, whereas the highest values were obtained in Zagreb with higher values of PH and NHI recorded at LN compared to HN, as opposed to Osijek and GY PH GPC (%) GNY NTA HI (% DM) NHI (% N) NUE N uptake efficiency (NUpE) (%) NUtE NUtE_PROT (% protein kg−1 N ha−1) NUE_PROT (% protein kg−1 N ha−1) NRE (%) BPE PANU
Summary
Competition for land, limited natural resources, and the co-occurrence of abiotic and biotic stresses all threaten global wheat production. Wheat productivity is increasing at a global rate of 1.1% per year (Dixon et al, 2009) against a predicted demand requirement of 1.7% year−1 until 2050 (Rosegrant and Agcaoili, 2010). Current wheat production demands a range of agrochemical inputs, including nitrogen (N) fertilizer. Between 85 and 90 million tons of N fertilizers are added to agricultural soils worldwide each year, and current predictions based on projected food demand show that this could increase to 240 million tons by 2050 (Good et al, 2004). N fertilizer represents the single most expensive input into wheat production and accounts for more than 70% of its associated greenhouse gas emissions (Mortimer et al, 2004). Excessive usage has a range of negative impacts on the environment, and it is estimated that 50−70% of applied N is lost from the plant–soil system through a combination of leaching, surface run-off, denitrification, volatilization, and microbial consumption (Peoples et al, 1995)
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