Nitrogen Type and Availability Drive Mycorrhizal Effects on Wheat Performance, Nitrogen Uptake and Recovery, and Production Sustainability.

Dario Giambalvo,Moisés A Sosa-Hernández,Gaetano Amato,Matthias C Rillig,Rosolino Ingraffia,Alfonso S Frenda

doi:10.3389/fpls.2020.00760

Abstract

Plant performance is strongly dependent on nitrogen (N), and thus increasing N nutrition is of great relevance for the productivity of agroecosystems. The effects of arbuscular mycorrhizal (AM) fungi on plant N acquisition are debated because contradictory results have been reported. Using 15N-labeled fertilizers as a tracer, we evaluated the effects of AM fungi on N uptake and recovery from mineral or organic sources in durum wheat. Under sufficient N availability, AM fungi had no effects on plant biomass but increased N concentrations in plant tissue, plant N uptake, and total N recovered from the fertilizer. In N-deficient soil, AM fungi led to decreased aboveground biomass, which suggests that plants and AM fungi may have competed for N. When the organic source had a low C:N ratio, AM fungi favored both plant N uptake and N recovery. In contrast, when the organic source had a high C:N ratio, a clear reduction in N recovery from the fertilizer was observed. Overall, the results indicate an active role of arbuscular mycorrhizae in favoring plant N-related traits when N is not a limiting factor and show that these fungi help in N recovery from the fertilizer. These results hold great potential for increasing the sustainability of durum wheat production.

Highlights

Durum wheat is a keystone crop in Mediterranean agroecosystems
arbuscular mycorrhizal (AM) fungal colonization was observed in the noninoculated treatments (–myc), the extent of the colonization was always less than 4%, very different from the values observed in the inoculated treatments (+myc; AM fungal inoculation treatment p < 2e−16; Figure 1 and Table 2)
The percentage of AM fungal colonization was higher in N0 than all other treatments, moderate differences were observed among all other treatments

Summary

Introduction

Durum wheat is a keystone crop in Mediterranean agroecosystems. Its performance is strongly dependent on the availability of soil nitrogen (N) throughout its development. Often only 50% or less of the N fertilizer applied to soil is recovered by cereals, and this percentage decreases as the rate of N fertilization increases (Foulkes et al, 1998; Raun and Johnson, 1999; Blankenau et al, 2002; Ruisi et al, 2015, 2016). This has important agro-environmental implications since, due to the high N mobility in the soil– plant–atmosphere system, N not used by plants contributes greatly to agriculture-related pollution through leaching, volatilization, and denitrification (Drinkwater et al, 1998; Limaux et al, 1999).

Methods

Results

Conclusion