EM biofertilizer affects growth and rhizosphere bacterial community of pigment pepper in Xinjiang of China

Abstract:

[Background] Effective microorganisms (EM) have been widely used in the farming in China, while the available information is limited regarding the impacts of EM biofertilizer on the growth and rhizosphere bacterial community structure of pigment pepper. [Objective] To clarify the growth-promoting effect of EM biofertilizer on pigment pepper in Xinjiang of China and uncover the influence of the biofertilizer on rhizosphere bacterial community structure. [Methods] The EM biofertilizer was inoculated into the roots of pigment pepper plants through irrigation. We determined the growth indexes, soil nutrient levels, and enzyme activities at the harvest stage to assess the impacts of EM biofertilizer on the pepper growth and soil quality. High-throughput sequencing of 16S rRNA was employed to investigate the impacts of EM biofertilizer on the composition and structure of rhizosphere bacterial community. [Results] Compared with the control group, the application of EM biofertilizer increased the plant height, fresh weight, single fruit weight, and number of fruits per plant by 23.89%, 85.41%, 42.31%, and 46.04%, respectively. Moreover, it increased the available nitrogen, the available phosphorus, and the activities of urease, sucrase, and peroxidase in the soil by 5.83%, 13.39%, 11.47%, 9.42%, and 21.43%, respectively. The application of EM biofertilizer significantly altered the alpha and beta diversity of bacteria in the rhizosphere soil and increased the relative abundance of beneficial bacteria including Proteobacteria, Acidobacteria, Gemmatimonadetes, Actinobacteria, and Firmicutes. Especially, the relative abundance of Xanthomonadaceae belonging to Proteobacteria was increased by 119.32%. At the genus level, the application of EM biofertilizer increased the relative abundance of Luteitalea, Luteimonas, Sphingobacterium, and Halomonas. Among them, the relative abundance of Luteimonas was increased by 244.17%, whereas that of Flavobacterium was lower than that in the control group. The microbial taxa showing positive correlations with soil physicochemical indices presented significantly increased relative abundance after the application of EM biofertilizer. [Conclusion] The application of EM biofertilizer regulates the rhizosphere microbial community structure by changing soil nutrient levels and enzyme activities, which further enriched beneficial bacteria with strong survival ability in saline-alkali land and promoted the growth of pigment pepper.

Key words:EM biofertilizer;pigment pepper;growth-promoting effect;rhizosphere bacterial community structure;soil enzyme activity