AUTHOR=Li Wei , Zhou Xiaonan , Yu Kang , Zhang Zhen , Liu Yang , Hu Naiyue , Liu Ying , Yao Chunsheng , Yang Xiaoguang , Wang Zhimin , Zhang Yinghua 

TITLE=Spectroscopic Estimation of N Concentration in Wheat Organs for Assessing N Remobilization Under Different Irrigation Regimes

JOURNAL=Frontiers in Plant Science

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2021.657578

DOI=10.3389/fpls.2021.657578

ISSN=1664-462X

ABSTRACT=<p>Nitrogen (N) remobilization is a critical process that provides substantial N to winter wheat grains for improving yield productivity. Here, the remobilization of N from anthesis to maturity in two wheat cultivars under three irrigation regimes was measured and its relationship to organ N concentration was examined. Based on spectral data of organ powder samples, partial least squares regression (PLSR) models were calibrated to estimate N concentration (<italic>N</italic><sub>mass</sub>) and validated against laboratory-based measurements. Although spectral reflectance could accurately estimate <italic>N</italic><sub>mass</sub>, the PLSR-based <italic>N</italic><sub>mass</sub>-spectra predictive model was found to be organ-specific, organs at the top canopy (chaff and top three leaves) received the best predictions (<italic>R</italic><sup>2</sup> &gt; 0.88). In addition, N remobilization efficiency (NRE) in the top two leaves and top third internode was highly correlated with its corresponding N concentration change (Δ<italic>N</italic><sub>mass</sub>) with an <italic>R</italic><sup>2</sup> of 0.90. Δ<italic>N</italic><sub>mass</sub> of the top first internode (TIN1) explained 78% variation of the whole-plant NRE. This study provides a proof of concept for estimating N concentration and assessing N remobilization using hyperspectral data of individual organs, which offers a non-chemical and low-cost approach to screen germplasms for an optimal NRE in drought-resistance breeding.</p>