Effects of exogenous silicon on root morphology of Elymus nutans seedlings under simulant drought stress

In order to explore the effect of exogenous silicon (Si) on the root morphology of Elymus nutans seedlings under drought stress, the total root length, root surface area, root volume, average root diameter, and root branch number of seedlings were determined by adding exogenous Si under polyethylene glycol (PEG-6000) simulated drought conditions. The results showed that the total length, root biomass, root surface area, root volume, average root diameter, branch root numbers, and root tip numbers of seedlings were increased with increasing concentrations of exogenous Si when treated with 15% PEG for 7 days. Nevertheless, these indices first increased and then decreased under the condition of 15% PEG for 21 days as the concentration of Si increased, and 0.5 mmol·L^–1 was found to be the best concentration for Si. Meanwhile, the root index of seedlings with the diameter range of R₁ (0～0.5 mm) increased significantly (P < 0.05) with Si addition. These results indicate that Si addition enhanced the ability of fine root differentiation and alleviated the damage due to drought stress to the root system of E. nutans seedlings by adjusting the root morphology of seedlings to adapt to the arid environment. This study provides an important reference for drought resistance research and the production and utilization of E. nutans.