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

Abstract

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 (Nmass) and validated against laboratory-based measurements. Although spectral reflectance could accurately estimate Nmass, the PLSR-based Nmass-spectra predictive model was found to be organ-specific, organs at the top canopy (chaff and top three leaves) received the best predictions (R2 > 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 (ΔNmass) with an R2 of 0.90. ΔNmass 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.

The end-use quality of wheat can be enhanced by optimal water management without incurring yield loss

“…Similarly, Santis et al. (2021) found that drought stress could lead to poor grain sets and yields, and Li et al. (2021) recorded low yields in plants subjected to low-level irrigation.…”

“…adequate supply of water. Similarly, Santis et al (2021) found that drought stress could lead to poor grain sets and yields, and Li et al (2021) recorded low yields in plants subjected to lowlevel irrigation. However, it has previously been reported that a slight or moderate water deficit prior to the stem elongation stage and slight water deficit during the grain-filling stage did not significantly reduce grain yield, which lead to a significant water conservation (Meng et al, 2016).…”

“…The accumulation of grain N occurs almost simultaneously with the decrease of leaf N content. It has also been reported that water deficit enhances N remobilization efficiency in wheat (Li et al, 2021). Consequently, a better understanding of the effects of water deficit on the changes in sucrose and N concentrations in different organs is important for clarifying the physiological mechanism whereby RDI influences grain filling and N accumulation characteristics.…”

Characterization of N distribution in different organs of winter wheat using UAV-based remote sensing

“…The operation of nitrogen varies in different growth stages and different organs in crops (Ohyama Takuji, 2010). Studies have indicated that different organs could have different effects on the crop spectral features (Li et al, 2015(Li et al, , 2021. However, few investigations under field conditions address the differences of estimated the NC in different organs when using UAV-based multispectral data.…”