Root growth angle and root hairs differentially regulate nitrous oxide emissions and nitrate leaching

Le résumé fourni par la source

Root growth angle and root hairs are key root traits that shape nitrogen capture, yet their effects on nitrous oxide (N₂O) emissions and nitrate leaching remain poorly understood; this study tested how these traits regulate nitrogen loss pathways in barley (Hordeum vulgare).Barley mutants with steeper root angles (Steep 1, Steep 2) or lacking root hairs (RHL), together with the wild-type cultivar Morex, were grown for seven weeks in soil mesocosms under recommended (160 kg N ha⁻¹) and reduced (80 kg N ha⁻¹) nitrogen rates; N₂O fluxes, nitrate leaching, plant traits and soil mineral nitrogen were quantified.Steep root growthangle mutants reduced root biomass allocation and root length density (RLD) in the top 10 cm and increased N₂O emissions, without affecting leaching; the hairless mutant (RHL) reduced nitrogen uptake, biomass and root diameter while elevating both N₂O and nitrate leaching.Steeper root systems elevate N₂O by depleting roots in the topsoil where most emissions originate, whereas root hairs reduce both N₂O and leaching by enhancing nitrogen uptake; breeding strategies should therefore treat these traits as context-dependent strategies for nitrogen-loss mitigation.

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