Dynamic changes in cellulose content and biomechanical properties of mycorrhizal roots during growth and decay

Aims Arbuscular mycorrhizal (AM) fungi have been found to increase plant biomass, cellulose content, and the associated root biomechanical properties, but little is known about how AM fungi affect the in situ root decay process in terms of the changes in the chemical and biomechanical properties. Methods In this study, we inoculated AM fungi to Bermuda grass ( Cynodon dactylon L.) and measured the biomass, the contents of cellulose and lignin, and the biomechanical properties, including tensile strength and Young’s modulus of the grass roots as they grew for 180 days and then decayed for 360 days after burning or for 60 days after the herbicide application. Results Results show that the AM fungi accelerated the accumulation of grass biomass and root cellulose content compared with non-mycorrhizal grass during the growth period. This effect of AM fungi made mycorrhizal grass generally maintained more biomass and cellulose content than non-mycorrhizal grass at every decaying stage. Inoculation of the AM fungi did not significantly change the root tensile strength or Young’s modulus, but it altered the correlations between tensile strength and root diameter, and Young’s modulus and root diameter. Mycorrhizal effects during the root decaying process appeared to diminish under herbicide treatment, compared with normal growth and burning treatments. Conclusion Our study highlights the important role of AM fungi in maintaining in situ root biomass (a proxy for carbon content) from decaying or decomposing.