Screening of saline-alkali tolerant microorganisms and their promoting effects on rice growth under saline-alkali stress

Soil salinization poses a global challenge, and cultivating rice on saline-alkali lands is a recognized strategy for exploiting and ameliorating these challenging environments, however, the yield and quality of rice are significantly lower compared to cultivation on non-saline lands. This study focused on the utilization of saline-alkali tolerant plant-growth-promoting microorganisms (PGPRs) and organic matter. Four PGPR strains were identified and subsequently fermented and propagated, and then combined in equal proportions and mixed with cow manure compost to prepare a PGPR amendment. This amendment was applied to rice cultivated in pots under saline-alkali stress. Agronomic traits were monitored at various growth stages to assess the amendment's impact on rice development. The results showed that under moderate saline-alkali stress, PGPR amendments significantly improved the physicochemical indicators of rice. Compared with the control group, rice plant height, root length and chlorophyll content increased by 113.56%, 43.19% and 95.43%, respectively. The antioxidant enzyme increased by 39.86%, and the levels of soluble sugars and proteins increased by 20.91% and 27.28%, respectively. Notably, rice under moderate saline-alkali stress showed greater improvements in response to the amendment compared to rice under mild stress conditions. These findings suggest that the amendments effectively mitigate the adverse effects of saline-alkali stress on rice growth, thereby offering a viable strategy for enhancing crop productivity in affected areas. [Display omitted] •Four strains of saline-alkali tolerant PGPR were isolated.•Rice growth was inhibited by varying degrees of saline-alkali stress.•Integrating PGPR with organic substrates avoided the limitations of individual use.•The application of PGPR amendment alleviated stress and increased rice biomass.•The synergy between PGPR and cow dung promoted rice development in saline soils.