Abstract
Optimising nitrogen fertiliser management in combination with using high nitrogen efficient wheat cultivars is the most effective strategy to maximise productivity in a cost-efficient manner. The present study was designed to investigate the associations between nitrogen utilisation efficiency (NUtE) and the allelic composition of the NAM genes in Australian wheat cultivars. As results, the non-functional NAM-B1 allele was more responsive to the nitrogen levels and increased NUtE significantly, leading to a higher grain yield but reduced grain protein content. Nitrogen application at different developmental stages (mid-tillering, booting, and flowering) did not show significant differences in grain yield and protein content. The NAM-A1 allelic variation is significantly associated with the length of the grain-filling period. While the NAM-A1 allele a was associated with a short to moderate grain-filling phase, the alleles c and d were related to moderate to long grain-filling phase. Thus, selection of appropriate combinations of NAM gene alleles can fine-tune the duration of growth phases affecting sink-source relationships which offers an opportunity to develop high NUtE cultivars for target environments.
Highlights
Breeding cultivars with high nitrogen use efficiency (NUE) is essential for sustainable wheat production
The timing of the N application was synchronised to several Zadoks growth stages: T1 = 100% of N rate was applied at NAM gene allelic composition and nitrogen utilisation efficiency of Australian wheat
3.1.1 Grain yield, protein content, N use efficiency (NUE), and its components were influenced by NAM gene allelic composition
Summary
Breeding cultivars with high nitrogen use efficiency (NUE) is essential for sustainable wheat production. NUE comprises two aspects, including nitrogen uptake efficiency (NUpE) that represents the capacity of plants to absorb nitrogen (N) from soil and nitrogen utilisation efficiency (NUtE) that represents the plant’s ability to use absorbed N to produce grain [1, 2]. Understanding the mechanisms regulating these two processes is essential to improve NUE in crop plants. The NUpE, and NUtE metabolic pathways are strongly influenced by genetic variation and environmental factors [3, 4].
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