Mycorrhizal roles in plant growth, gas exchange, root morphology, and nutrient uptake of walnuts

Arbuscular mycorrhizal fungi (AMF) are one of the most important endophytic fungi in plants that form arbuscular mycorrhizas with roots.Arbuscular mycorrhizas can absorb mineral nutrients for plant partners through forming extensive networks of AMF hyphae in the soil in exchange of photosynthetically fixed carbon and lipids (Walder and van der Heijden 2015, Wu et al. 2019a).As a result, mycorrhizas promote plant growth under various abiotic and biotic stress conditions (Gąstoł and Domagała-Świątkiewicz 2015, He et al. 2019, Wu et al. 2019b, Zhang et al. 2019, 2020).Plant roots have a high degree of phenotypic plasticity, and its morphology is affected by numerous factors, including soil microorganisms.Previous studies indicated that AMF affected the root morphology and photosynthetic rate of host plants (Heinonsalo et al. 2016).In trifoliate orange, inoculation with Acaulospora scrobiculata or Funneliformis mosseae could improve root morphological traits than noninoculation (Wu et al. 2016).In tea plants, AMF remarkably improved total root length and volume, while decreased root hair length and number (Shao et al. 2018).However, AMF colonisation had no sig-Mycorrhizal roles in plant growth, gas exchange, root morphology, and nutrient uptake of walnuts