Background Bermudagrass (Cynodon dactylon) has a long history as an excellent forage grass, and salt stress will inhibit its growth and development. In order to minimize the damage, it is necessary to continuously develop innovative technologies and management strategies. Results This study evaluated the salt tolerance of new Bermudagrass strains 'FB2019R101' and 'FB2019R105' compared to commercial varieties 'Wrangler' and 'A12359' under simulated soil salinity conditions through seawater irrigation. Through correlation analysis of growth, physiological, and nutritional indicators, and principal component analysis, core indicators and weights for salt tolerance evaluation were identified. The salt-tolerant varieties were 'FB2019R101' and 'FB2019R105'. Under salinity stress, the plants of Bermudagrass varieties with salt tolerance suffered less damage as a whole, which could better regulate the osmotic balance inside and outside cells, accumulate more nutrients and have stronger ability to resist salt damage. The expression level of salt-tolerant variety CdCINV1, CdSPS1, CdSUS5, and CdSWEET6 was up-regulated under salt stress. CdCINV1, CdSPS1, CdSUS5 can promote the transformation of sucrose into glucose and fructose in Bermudagrass under salt stress, and CdSWEET6 can promote the accumulation of fructose. Conclusions 'FB2019R101' and 'FB2019R105' exhibited higher salt tolerance, with minimal impact on their biomass, physiological, and nutritional indicators under salt stress. The comprehensive evaluation revealed a salt tolerance ranking of 'FB2019R105' > 'FB2019R101' > 'Wrangler' > 'A12359'. This study provides significant reference for the bioremediation of coastal saline soils and promotes research on the application of Bermudagrass under salt stress conditions. CdCINV1, CdSPS1, CdSUS5, and CdSWEET6 can improve the salt tolerance of plants by regulating the changes of carbohydrates.

AimsEnvironmental stresses can influence root mechanical strength, the impact of submersion of the water level fluctuation zone on the root mechanical strength of Cynodon dactylon was evaluated in this study.MethodsVariations in the physicochemical properties (root weight density and root activity), mechanical strengths (tensile and pullout strength) and failure types of C. dactylon roots were investigated using a submersion experiment with 8 durations (0, 15, 30, 60, 90, 120, 150, 180 d), with a treatment without submersion serving as the control (CK). Additionally, corresponding variation in the microstructure of the roots was observed.ResultsThe root weight density, root activity, root tensile strength and pullout strength of C. dactylon rapidly decreased, followed by a gradual decrease with increasing duration, and the reductions during the first 15 d of submersion accounted for 65.15%, 75.86%, 61.14% and 68.26% of the maximum reduction during the submersion process, respectively. Negative power function relationships were found between root mechanical strength and root diameter. Submersion increased the proportion of fracture failures during the pullout process. Moreover, the influence of submersion on root mechanical strength and failure type was regulated by a reduction in root activity.ConclusionsSubmersion deteriorates the mechanical properties of C. dactylon roots and alters their failure type.

Wave erosion is the main erosion type in the water -level fluctuation zone (WLFZ) of the Three Gorges Reservoir Area (TGRA). Despite vegetation can effectively mitigate wave erosion in the WLFZ, its influence on the wave force and wave erosion remains unclear. Therefore, the wave experiments were conducted under 3 Cynodon dactylon coverage rates (0, 30% and 60%) and 9 wave conditions (3 wave heights of 4, 6 and 8 cm combined with 3 wave periods of 1, 2 and 3 s) to analyse the wave force (expressed as the wave pressure on the slope surface and the pore water pressure in the slope) and wave erosion rate, and the factors influencing wave erosion were identified. The results indicated that the wave pressure, pore water pressure and wave erosion rate increased by 19.14%-104.75%, 16.84%-65.04% and 23.33%-91.64%, respectively, as wave height increases. The wave pressure decreased by 1.50%-31.23% followed by an increase by 22.05% to 87.10% with the increase of wave period, whereas the pore water pressure and wave erosion rate decreased by 28.33%-53.59% and 20.46%- 63.59%, respectively. However, these quantities decreased by 2.10%-50.84%, 17.06%-40.23% and 17.28%- 82.18%, respectively, with the increase of Cynodon dactylon coverage rate. It was also discovered that the pore water pressure and Cynodon dactylon coverage rate attained the highest positive and negative correlation coefficients with the wave erosion rate, respectively. In addition, pore water pressure accumulation is the most critical influence factor on wave erosion, and Cynodon dactylon could effectively reduce the pore water pressure via its roots, thus improving the slope wave erosion resistance. This study could be useful to understand the mechanism of plants on controlling wave erosion and could provide a scientific reference for wave erosion control and the ecological construction in the WLFZ.

The stability of riverbank slopes is crucial in watershed ecology. The morphology and tensile strength properties of plant roots play a significant role in slope stability, which is of great importance for the ecological stability of riverbanks. The Jinsha and Yalong River basins are the largest hydropower bases in China and are in the ecologically fragile areas of the dry and hot river valleys, yet fewer studies are available on these basins. Further studies on the growth morphology and root mechanical properties of plant roots in the riparian zone at different elevations have not been reported. Therefore, we selected the dominant species of Cynodon dactylon root as the research subject, analyzed the root morphology, and conducted indoor single-root tensile tests to study its root structure and mechanical properties at various elevations. The results showed that the root morphology of Cynodon dactylon was positively correlated with elevation. Compared to low elevations (L and M), the root length increased by 57.3% and 21.47%, the root diameter increased by 24.85% and 13.92%, the root surface area increased by 93.5% and 67.37%, and the total root volume increased by 119.91% and 107.36%. As the elevation gradient increased, the flooding time decreased, leading to more developed plant roots for Cynodon dactylon. The Young's modulus ranged from 148.43 to 454.18 MPa for Ertan Cynodon dactylon roots and 131.31 to 355.53 MPa for Guanyingyan Cynodon dactylon roots. The maximum tensile strength, ultimate tensile strength, ultimate elongation, and Young's modulus of the plant root of the Cynodon dactylon showed a power function relationship with the diameter. The maximum tensile strength increased as the diameter increased, while the remaining properties decreased following a power function relationship. The maximum tensile strength, ultimate tensile strength, and Young's modulus of Cynodon dactylon were positively correlated with elevation, while the ultimate elongation was negatively correlated with elevation. The results elucidate the influence of elevation on the root morphology and mechanical properties of dominant riparian species. This provides a theoretical basis for managing and protecting riparian slopes in ecologically fragile areas.