Growth and physiological characteristics of forage bermudagrass in response to salt stress

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.