High-throughput phenotyping of nitrogen and biomass partitioning of central European wheat cultivars and breeding lines during grain filling in different climatic zones

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The challenge to phenotyping - one of the bottlenecks in breeding research in improvement of agricultural practices - is to develop high-throughput precision phenotyping techniques. To ensure wheat yield stability and grain quality, the key physiological traits for genetic improvement are to obtain high grain protein content without a decrease in grain yield of wheat. Therefore, our hypothesis is that high-throughput spectral phenotyping of plant traits of biomass and grain yield formation over time during grain filling can assess the relationships between Nrem/Nup and sink/source relations to achieve high N use efficiency and to improve selection efficiency for yield and protein content in wheat breeding. The ultimate objective is to obtain sufficient knowledge to identify the potential traits of Nrem (N remobilization), Nup (N uptake), Nsto (N storage) and sink-source relations which control the processes of grain N deposition during grain filling, thereby providing the key physiological traits for genetic improvement of grain protein concentration without affecting grain yield of wheat using high-throughput and cost-effective phenotyping techniques. The specific objectives are: i) to assess the sensitivity of spectral indices and/or other algorithms for detecting genotypic effects on total grain N deposition, Nrem, Nup, Nsto and sink-source relations during the grain filling at optimal soil N levels and under a range of climatic zones; ii) to evaluate the validity of spectral indices and other algorithms as a potential high-throughput phenotyping technique for total grain N deposition, Nrem, Nup, Nsto and sink-source relations; iii) to compare with image-based approaches; and iv) to link spectral indices/best algorithms with the genetic map of the wheat genome allowing a better understanding of the importance of loci for grain yield and N use efficiency of winter wheat during grain filling. Significance: i) This knowledge will ultimately lead to a more rational and effective approach to high-throughput phenotyping using spectral sensors for a better understanding of grain N deposition mechanisms and to find the suitable measures for the desired traits in order to obtain high yielding potential and high N concentrations of winter wheat within the context of climate changes; ii) The successful implementation of high-throughput precision phenotyping technologies in field-oriented breeding will narrow the gap between our current genotyping and phenotyping capabilities; and iii) Plant traits identified in different climatic zones for high yielding potential and high grain protein concentration will meet the challenges ahead, which requires the scale of quantum advances for the physiological changes being seen in future climate changes.