15N Natural Abundance Evidences a Better Use of N Sources by Late Nitrogen Application in Bread Wheat.

Teresa Fuertes-Mendizábal,Ana Aizpurua,José M Estavillo,Ander Castellón,María Begoña González-Moro,Ximena Huérfano,Miren K Duñabeitia,Carmen González-Murua

doi:10.3389/fpls.2018.00853

Abstract

This work explores whether the natural abundance of N isotopes technique could be used to understand the movement of N within the plant during vegetative and grain filling phases in wheat crop (Triticum aestivum L.) under different fertilizer management strategies. We focus on the effect of splitting the same N dose through a third late amendment at flag leaf stage (GS37) under humid Mediterranean conditions, where high spring precipitations can guarantee the incorporation of the lately applied N to the soil-plant system in an efficient way. The results are discussed in the context of agronomic parameters as N content, grain yield and quality, and show that further splitting the same N dose improves the wheat quality and induces a better nitrogen use efficiency. The nitrogen isotopic natural abundance technique shows that N remobilization is a discriminating process that leads to an impoverishment in 15N of senescent leaves and grain itself. This technique also reflects the more efficient use of N resources (fertilizer and native soil-N) when plants receive a late N amendment.

Highlights

Nitrogen is one of the essential nutrients required for crop productivity, which is mainly provided in form of fertilizers
The specific objectives of the present work were: firstly, to explore whether the natural abundance of N isotopes technique could be used to understand the movement of N within the plant during vegetative and grain filling phases in wheat crop and, secondly, to evaluate the potentiality of δ15N value in tissues as a physioagronomic indicator to assess the effect of different fertilizer managements on nitrogen use efficiency (NUE) by wheat
A third late N-fertilizer application in wheat crop at GS37 has been proposed as an agronomic management aimed to increase the NUE by the crop; and this application results interesting in our region (Fuertes-Mendizábal et al, 2010a), with a monthly average rainfall of 70 mm from March to

Summary

Introduction

Nitrogen is one of the essential nutrients required for crop productivity, which is mainly provided in form of fertilizers. The overuse of fertilizers in nowadays agriculture is often associated with a low nitrogen use efficiency (NUE) by the crop, since most crop plants absorb only 30–50% of the N fertilizer supplied, depending on the soil or the environment (Tilman et al, 2002; Ladha et al, 2005). This N overapplication of fertilizer derives in a risk of negative impacts to the environment. Gate (1995) and Oury et al (2003) proposed the application of a third amendment in the flag leaf stage (GS37), which would

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