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Arbuscular mycorrhizal fungi colonization facilitates nitrogen uptake in cotton under nitrogen-reduction condition

Summary

This study shows that beneficial soil fungi (arbuscular mycorrhizal fungi) can help cotton plants absorb more nitrogen from soil, especially when nitrogen fertilizer is reduced. The fungi form partnerships with cotton roots and extend into the soil with thread-like structures that absorb nitrogen and transport it to the plant. The research demonstrates that reducing nitrogen fertilizer while using these beneficial fungi could improve crop growth while reducing environmental pollution from fertilizer runoff.

Background

Cotton is an economically important crop whose yield and quality are strongly influenced by soil nitrogen availability. Low nitrogen use efficiency is a major challenge in cotton cultivation, with only 25-50% of applied nitrogen being assimilated by crops. Arbuscular mycorrhizal fungi (AMF) have been proposed as an effective solution to improve nitrogen uptake efficiency, particularly under nutrient-deficient conditions.

Objective

To investigate whether symbiosis between arbuscular mycorrhizal fungi and cotton roots could improve nitrogen absorption capacity under different nitrogen application rates, and to quantify the contributions of mycelium versus roots to nitrogen uptake of different nitrogen forms.

Results

AMF colonization contributed 5.89-24.35% to root NO₃⁻-N uptake and 12.37-13.16% to NH₄⁺-N uptake depending on nitrogen level. Under nitrogen-reduction conditions, mycelial contributions to nitrogen uptake increased significantly. AMF colonization significantly increased root tissue density, cotton biomass, and soil microbial activity while being negatively correlated with soil total organic carbon.

Conclusion

Under nitrogen-reduction conditions, cotton roots become more dependent on mycelial contributions to NO₃⁻-N uptake. AMF colonization improves root structure and tissue density, potentially prolonging root functional lifespan and reducing carbon and nitrogen consumption in root reconstruction, though this mechanism requires further verification through direct measurement of root turnover rates.
  • Published in:BMC Plant Biology,
  • Study Type:Experimental Study,
  • Source: PMID: 40859120, DOI: 10.1186/s12870-025-07204-3
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