Contrasting Nitrogen Fertilisation Rates Alter Mycorrhizal Contribution to Barley Nutrition in a Field Trial.

Tom Thirkell,Duncan Cameron,Angela Hodge

doi:10.3389/fpls.2019.01312

Tom Thirkell, Duncan Cameron + Show 1 more

Open Access

https://doi.org/10.3389/fpls.2019.01312

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Abstract

Controlled environment studies show that arbuscular mycorrhizal fungi (AMF) may contribute to plant nitrogen (N) uptake, but the role of these near-ubiquitous symbionts in crop plant N nutrition under natural field conditions remains largely unknown. In a field trial, we tested the effects of N fertilisation and barley (Hordeum vulgare L.) cultivar identity on the contribution of AMF to barley N uptake using 15N tracers added to rhizosphere soil compartments. AMF were shown capable of significantly increasing plant 15N acquisition from root exclusion zones, and this was influenced by nitrogen addition type, N fertiliser application rate and barley cultivar identity. Our data demonstrate a previously overlooked potential route of crop plant N uptake which may be influenced substantially and rapidly in response to shifting agricultural management practices.

Highlights

Nitrogen (N) is usually the most limiting mineral nutrient to plant growth (Agren et al, 2012) and maintaining modern agricultural production requires frequent and substantial application of fertiliser to farm soils
Adding 15N isotope tracers to mesh-walled soil compartments in a field trial, we examined the role of arbuscular mycorrhizal fungi (AMF) in the N acquisition by barley (Hordeum vulgare L.) cultivars “Meridian” and “Maris Otter”
The enrichment of 15N in barley shoots suggests a role for AMF-facilitated N acquisition by crop plants, a phenomenon not previously observed in a field setting

Summary

Introduction

Nitrogen (N) is usually the most limiting mineral nutrient to plant growth (Agren et al, 2012) and maintaining modern agricultural production requires frequent and substantial application of fertiliser to farm soils. There is economic and ecological pressure on farmers to optimise the N uptake efficiency of crop plants (Hawkesford, 2014) and by reducing the reliance on non-renewable inputs, improve the sustainability of agriculture (Pretty, 2008). This progress will require the integration of biological and ecological processes into agriculture, and better understanding of soil microbial communities and their roles in nutrient cycling (Rillig et al, 2016, Pretty, 2018). While the role of AMF in biogeochemical cycles is undoubtedly complex, of pressing need is Mycorrhiza-Mediated Barley Nitrogen Nutrition to determine the extent to which plants rely on these symbionts for mineral nutrient acquisition

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