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Front. Plant Sci. | doi: 10.3389/fpls.2019.01372

A Robust Automated Image-based Phenotyping Method for Rapid Vegetative Screening of Wheat Germplasm for Nitrogen Use Efficiency

 Giao N. Nguyen1*,  Pankaj Maharjan1,  Lance Maphosa1, Jignesh Vakani1, Emily Thoday-Kennedy1 and  Surya Kant1
  • 1Agriculture Victoria, Grains Innovation Park, Horsham, Australia

Nitrogen use efficiency (NUE) in crops is generally low, with more than 60% of applied nitrogen (N) being lost to the environment, which increases production costs and affects ecosystems and human habitats. To overcome these issues, the breeding of crop varieties with improved NUE is needed, requiring efficient phenotyping methods along with molecular and genetic approaches. To develop an effective phenotypic screening method, experiments on wheat varieties under various N levels were conducted in the automated phenotyping platform at Plant Phenomics Victoria, Horsham. The results from the initial experiment showed that two relative N levels; 5 mM and 20 mM, designated as low and optimum N, respectively, were ideal to screen a diverse range of wheat germplasm for NUE on the automated imaging phenotyping platform. In the second experiment, estimated plant parameters such as shoot biomass and top-view area, derived from digital images showed high correlations with phenotypic traits such as shoot biomass and leaf area seven weeks after sowing, indicating that they could be used as surrogate measures of the latter. Plant growth analysis confirmed that the estimated plant parameters from the vegetative linear growth phase determined by the “broken-stick” model could effectively differentiate the performance of wheat varieties for NUE. Based on this study, vegetative phenotypic screens should focus on selecting wheat varieties under low N conditions, which were highly correlated with biomass and grain yield at harvest. Analysis indicated a relationship between controlled and field conditions for the same varieties, suggesting that greenhouse screens could be used to prioritise a higher value germplasm for subsequent field studies. Overall, our results showed that this phenotypic screening method is highly applicable and can be applied for the identification of N-efficient wheat germplasm early at the vegetative growth phase.

Keywords: high-throughput phenotyping, Digital imaging, controlled environment, Plant growth analysis, Broken-stick model

Received: 28 Jun 2019; Accepted: 04 Oct 2019.

Copyright: © 2019 Nguyen, Maharjan, Maphosa, Vakani, Thoday-Kennedy and Kant. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Dr. Giao N. Nguyen, Agriculture Victoria, Grains Innovation Park, Horsham, Horsham, Victoria, Australia, giao.nguyen@agriculture.vic.gov.au