Arbuscular mycorrhizal fungi indicators
The AMF spores were isolated through the process of wet sieving and
sucrose centrifugation method (McKenney and Lindsey, 1987). The
extraradical hyphae were extracted and stained with trypan blue
(Jakobsen et al., 1992), and hyphal length density was quantified using
a microscope with a gridded reticule at 250x magnification (Zhang et
al., 2016). The root samples were cleared with 10% (w/v) KOH at 90 °C
for 30 min then stained with trypan blue (Phillips and Hayman, 1970).
And the degree of AMF colonization was estimated according to the method
used a previous study (Mei et al., 2019).
To quantify the effect of GCF on AMF, we calculated the response index:
\begin{equation}
Response\ index=\ln{\left(X_{\text{with\ global\ change\ factor}}\right)-ln(X_{\text{without\ global\ change\ factor}})}\nonumber \\
\end{equation}Where X was AM fungal root colonization, soil hyphal length
density, and spore density. The response index of AM fungal indicators
under each GCF treatment was calculated separately. If the index
> 0, the treatment has a positive effect on AM fungi. On
the contrary, if the response index < 0, the GCF has a
negative effect on AM fungi (Xu et al., 2024).