Regulation of nitrogen application on peanut seed germination and spermosphere bacterial community structure under salt stress

[Objective]Salt stress affects seed germination and peanut growth, and increasing seed germination rate and healthy seedling rate under salt stress by fertilization application is one of the important strategies of high-yield and high-efficiency cultivation of peanut in saline-alkali soil. The bacterial community structure of spermosphere soil is closely related to seed germination and plant growth. [Methods] In this study, we set up three nitrogen levels of 0 kg.m-2, 90 kg.m-2, and 180 kg.m-2 with a salt-tolerant peanut variety (Huayu 25, HY25) as experimental materials. Potted experiments and high-throughput sequencing techniques were used to study the effects of nitrogen fertilizer application on the spermosphere bacterial community structure, germination and yield of peanut under salt stress. [Results] Salt stress significantly inhibited the peanut seeds germination and decreased the peanut yield. The application of nitrogen fertilizer increased the germination rate and peanut yield, and the optimal nitrogen application was 90 kg.m-2. Proteobacteria, Actinobacteria, Firmicutes, Acidobacteria, Bacteroidetes, Chloroflexi, and Gemmatimonadetes were the dominant phyla in peanut spermosphere soil of different groups. At the genus level, salt stress increased the relative abundance of beneficial bacteria Bacteroides, but induced a large number of harmful Streptococcus, whereas the relative abundance of the beneficial bacteria genera Bacillus, Sphingomonas, and Lysobacter were decreased. Nitrogen application under salt stress can improve the spermosphere soil microenvironment and increase the relative abundance of beneficial soil bacteria Bacteroides, Bacillus, and Sphingomonas, which is helpful to soil restoration and fertility improvement, and can also enhance the stress resistance of peanuts. [Conclusion] The study can provide important reference for improving the spermosphere soil bacterial environment, increasing the rate of peanut emergence and salt tolerance, and provide theoretical and technical basis for improving the production capacity of peanut in saline-alkali soil.