Nitrogen fertilization disrupts the temporal dynamics of arbuscular mycorrhizal fungal hyphae but not spore density and community composition in a wheat field. Nitrogen fertilization disrupts the temporal dynamics of arbuscular mycorrhizal fungal hyphae but not spore density and community composition in a wheat field

 Elucidating the temporal dynamics of arbuscular mycorrhizal (AM) fungi is critical for understanding their functions. Furthermore, research investigating the temporal dynamics of AM fungi in response to agricultural practices remain in its infancy.  We investigated the effect of nitrogen fertilization and watering reduction on the temporal dynamics of AM fungi, across the lifespan of wheat.  Nitrogen fertilization decreased AM fungal spore density, extra-radical hyphal density, and intra-radical colonization rate in both watering conditions. Nitrogen fertilization rather than watering reduction affected AM fungal community composition in soil but not in roots. The temporal analysis revealed that AM fungal extra-radical hyphal density and intra-radical colonization rate were higher under conventional watering and lower under reduced watering in March than in other growth stages at low (≤ 70 kg N ha-1 yr-1) but not at high (≥ 140) nitrogen fertilization levels. AM fungal spore density was lower in June than in other growth stages and community composition varied with plant development at all nitrogen fertilization levels, regardless of watering conditions.  This study demonstrates that high nitrogen fertilization levels disrupt the temporal dynamics of AM fungal hyphal growth but not sporulation and community composition.