# Influence of Suillus grevillea on the Root Morphology, Growth and Rhizosphere Soil Properties of Quercus variabilis Blume Seedlings with Root Pruning

## TL;DR

This study shows that the fungus Suillus grevillea helps Quercus variabilis seedlings recover from root pruning by improving root growth and soil conditions.

## Contribution

The novel finding is that Suillus grevillea inoculation compensates for the negative effects of root pruning on oak seedlings.

## Key findings

- Inoculated plants showed higher shoot and root dry weights and nutrient contents compared to noninoculated plants.
- Root pruning altered hormone levels and root morphology, but these effects were mitigated by Suillus grevillea.
- Soil properties improved with Suillus grevillea, enhancing the rhizosphere microenvironment.

## Abstract

Root pruning affects the ability of roots of Quercus variabilis Blume to absorb water and nutrients. Suillus grevillea can form a mutualistic symbiosis with Quercus variabilis Blume. A pot experiment in three compartments with two inoculation treatments (inoculation with Suillus grevillea and noninoculation control) and four different root pruning treatments (0, 1/4, 1/3, and 1/2 of the main root length pruned) was conducted. The shoot dry weight, root dry weight, shoot and root N, P and K contents, root morphological and physiological parameters of Quercus variabilis Blume seedlings, and soil properties were measured. The results showed that root pruning affected root endogenous hormone levels, root morphology, shoot and root nutrient absorption, and biomass accumulation. Compared with those without inoculation, the shoot dry weight, root dry weights, shoot and root N, and P and K contents of inoculated plants were greater, regardless of the degree of root pruning. The root length, root projection area, root surface area, root average diameter, root density, root volume, and root tip number increased in response to Suillus grevillea. The root auxin (IAA), cytokinin (CTK), gibberellin (GA), zeatin riboside (ZR), and salicylic acid (SA) contents were greater in inoculated Quercus variabilis Blume seedlings than in noninoculated plants. Inoculation with Suillus grevillea improved the soil microenvironment around the seedlings. Suillus grevillea can compensate for the adverse effects of root pruning on nutrient absorption, root morphological and physiological growth and the soil properties of Quercus variabilis Blume seedlings.