Abstract
Introduction: The mechanical properties of plant roots, such as tensile strength and force, play a crucial role in anchoring plants and stabilizing soil against mechanical stresses like wind, compaction, and erosion. These properties directly influence plant survival and ecosystem stability. Therefore, identifying factors affecting the improvement of root mechanical properties is of particular importance. Among biological factors, arbuscular mycorrhizal fungi have been proposed to enhance root physiological function. However, their impact on root mechanical properties remains underexplored, particularly in native woody species of Iran. This study aimed to evaluate the effects of the arbuscular mycorrhizal fungi Rhizophagus irregularis and Funneliformis mosseae on the root mechanical properties of Pistacia atlantica Desf. and Celtis caucasica L.
Materials and Methods: For this purpose, ten four-year-old seedlings of each of the two studied species were selected, including five control plants and five plants inoculated with arbuscular mycorrhizal fungi Rhizophagus irregularis and Funneliformis mosseae. Seedlings were selected based on uniform growth status and overall health condition to minimize the influence of confounding factors and to ensure a reliable assessment of the AMF treatment effect. Following the complete excavation of the root systems from the soil, intact root samples were carefully collected. In total, between 42 and 66 healthy root samples were obtained per species. Subsequently, tensile strength and tensile force tests were conducted on the collected root samples to evaluate their mechanical properties.
Results: Analysis of covariance showed that in the P. atlantica, mycorrhizal treatment had no significant effect on tensile force and tensile strength (p > 0.05), considering root diameter as a covariate. However, in C. caucasica, mycorrhizal treatment significantly increased tensile force (p < 0.001), such that the average tensile force in the mycorrhizal treatment was 146.77 N and 138.03 N in the control, and the maximum tensile force in the mycorrhizal treatment reached 940.7 N. Moreover, in both species, positive and negative power function relationships were found between root diameter and mechanical properties, indicating that an increase in root diameter resulted in increased tensile force and decreased tensile strength, respectively
Conclusion: Although mycorrhizal treatment is generally applied with the purpose of increasing the resistance of plants against biological and climatic stresses, its effect on root mechanical properties can be significantly dependent on the plant species. In this respect, depending on the species, mycorrhizal fungi treatment of seedlings in bioengineering and forest restoration programs can be of major importance.