Relationship between nutrient accumulation in broomcorn millet (Panicum miliaceum L.) and microbial community under different salinity soils

Background and aims

Increased soil salinization is the major cause of soil degradation. With the increase in soil salinization, accompanied by nutrient deficiency, the mechanisms of improving nutrient uptake and utilization by rhizosphere microorganisms under saline-alkaline conditions are largely unknown.

Methods

The growth parameters and accumulation of nutrients by broomcorn millet (Panicum miliaceum L.) were assessed under saline-alkaline conditions. Furthermore, the soil physicochemical properties and the types of rhizosphere microorganisms were determined.

Results

Broomcorn millet adapted to high saline-alkaline conditions by reducing its height and leaf area and increasing its root-shoot ratio. Salinity is an important factor that regulates the composition of the microbial community. Under high salinity (HS) treatment, the rhizosphere reshaped the microbial communities by recruiting specific beneficial microbes, namely Nocardioides, Saccharimonadal, and Nitriliruptoraceae bacteria that promote soil nutrient cycling and Operculomyces, Alternaria and Cryptococcus fungi that are involved in the decomposition of organic matter and the absorption of nutrients. In addition, the microbial community is influenced by the rhizosphere compartment, and more unique fungal operational taxonomic units (OTUs) are recruited in the high salinity rhizosphere (HS_R) compared to the high salinity non-rhizosphere (HS_NR). The changes in the microbial communities may promote the cycling of soil nitrogen (N) and phosphorus (P) in high salinity soil and ultimately promote the accumulation of P in all the organs and improve the N use efficiency of the plants.

Conclusion

The findings of this study reveal the mechanism of the adaptation of broomcorn millet to different levels of salinity stress and provide insights into microbial and fertilizer management in saline-alkali land.