Halophilic and halotolerant bacteria as sustainable bioinputs to improve quinoa (Chenopodium quinoa) growth in saline soils

Context Soil salinization represents a significant threat to agricultural productivity, particularly in arid and semi-arid regions. Quinoa (Chenopodium quinoa Willd.), a facultative halophyte with high nutritional value and tolerance to abiotic stresses, is a promising crop for saline agriculture. Aims In this study, we evaluated the potential of halophilic and halotolerant plant growth-promoting bacteria (PGPB), previously isolated from hypersaline environments, to enhance quinoa performance under saline stress. Methods A greenhouse experiment was conducted with quinoa plants (cv. Titicaca) subjected to three salinity levels (electrical conductivities of 0.5, 6.5 and 13 dS m−1) and eight bacterial treatments, including five single strains and two consortia. Physiological, morphological, and biochemical parameters were assessed over 87 days. Key results Bacterial inoculation enhanced cumulative photosynthesis, pigment content, and soil biological activity, while reducing proline accumulation compared with non-inoculated controls under saline conditions. The strains Kushneria sp. T3.7 and Bacillus sp. HX11 significantly mitigated the impacts of salinity, maintaining physiological function and biomass accumulation similar to that of unstressed plants. Principal component analysis showed different mechanisms of stress alleviation for specific strains, depending on salinity level. Conclusions Our findings support the potential of halophilic and halotolerant PGPB for the development of bioinputs for improving the growth and the physiological status of halophyte crops as quinoa under saline stress. Implications These results offer an agricultural strategy for salt-affected soils using extreme-environments-adapted microbial inoculants.