Study on root architecture characteristics of wild Lespedeza bicolor in flatland and sloped sites

Our objective was to study the root differences of Lespedeza bicolor under natural conditions in flatland and sloped sites, and to reveal the root changes and adaptive strategies of plants growing in different sites. The root distribution and fractal characteristics of two years old L. bicolor growing in flatland and sloped conditions (24°, 35°, 45°) in Jiufeng Forest Farm were compared by excavating whole root systems and using a Win-RHIZO root analysis system. 1) There were significant differences in the root distribution range and number of base roots growing in different directions between the four sites (P < 0.05). Root systems tended to occur in the surface layer in flatland sites, while vertical expansion of L. bicolor root systems tended to be enhanced in sloped sites. 2) Sloped sites had more significant effects on root biomass and root-shoot ratio than flatlands, and root biomass was the highest in 35° sloped sites. 3) The root depth-width ratio and root-shoot ratio of L. bicolor tended to increase with increasing slope. 4) Different site conditions had certain effects on the root architecture of L. bicolor. The changes in root length, root fractal dimension, and root abundance were consistent between the four site conditions, which showed as 35° > flatland > 45° > 24°. Root volume and root surface area differed between the sites (35° > 45° > flatland > 24°). The root length, root surface area, root volume, fractal dimension, and root abundance of L. bicolor were the highest in the 35° sloped sites and the root systems were more developed. The results show that different site conditions affect root morphogenesis in varying degrees, and plants form unique root adaptation strategies, which shows the plasticity of plant roots to adapt to heterogeneous environments.