Arbuscular Mycorrhizal Fungi Can Increase Nitrogen Use Efficiency in Aerobically Grown Rice Under Water‐Limited Conditions

Summary

This field trial evaluated the potential of arbuscular mycorrhizal fungal inoculation to improve nitrogen use efficiency and water relations in aerobically grown rice across three commercial varieties and multiple nitrogen and water availability scenarios. The authors found that whilst water availability was the primary constraint on grain biomass, AM fungal inoculation selectively improved grain nitrogen concentration and nitrogen use efficiency under water stress in certain varieties. The findings suggest AM fungi could support transitions to aerobic rice production, though benefits are likely constrained by low soil nitrogen availability.

Regional applicability

This study was conducted in Australia and tested commercial rice varieties adapted to aerobic systems. The findings are potentially relevant to United Kingdom rice trials or research into alternative cereals and mycorrhizal inoculation, though UK rice production is limited and environmental conditions differ substantially. The methodology and insights on AM fungi support for water-stressed aerobic cereal production may inform UK research into drought-resilient grain systems.

Key measures

Grain biomass, grain nitrogen concentration, nitrogen use efficiency, plant water use, stomatal conductance, carbon assimilation, across three nitrogen application rates (160 kg urea ha⁻¹, 320 kg urea ha⁻¹, and split 160 kg urea ha⁻¹ twice), AM fungal inoculation (Rhizophagus irregularis), and three rice varieties (Reiziq, Topaz, Viand)

Outcomes reported

The study measured grain biomass production, grain nitrogen concentration, nitrogen use efficiency, plant water use, stomatal conductance, and carbon assimilation across different watering and nitrogen application treatments with and without AM fungal inoculation. Results showed that water availability was the strongest determinant of grain biomass, and AM fungal inoculation increased grain N concentration and N use efficiency in some rice varieties under water-limiting conditions.

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