Shift of allelochemicals from Sorghum halepense in the soil and their effects on the soil's bacterial community

Abstract

Johnsongrass (Sorghum halepense [L.]Pers.), an exotic invasive weed in China, secretes the phenolic compounds, p‐hydroxybenzoic acid (p‐HBA) and p‐hydroxybenzaldehyde (p‐HBAL), as the dominant allelochemicals in the root exudates. To better understand how these two allelochemicals affect the soil microbial community in the rhizosphere of S. halepense, the fate of these compounds in the invaded soil and the effect of these phytotoxins on the soil bacterial community were evaluated. The concentrations of the allelochemicals in the soil were determined by a high‐performance liquid chromatography‐ultraviolet/photodiode array after 1, 2, 4, 6, 12 and 24 h of treatment. MiSeq sequencing was undertaken to understand how the bacterial populations in the soil were affected by the allelochemicals. The HPLC results indicated that p‐HBA was degraded by the microorganisms that were present in the soil after 1 h and disappeared after 6 h of incubation. The compound, p‐HBAL, initially was converted to p‐HBA and then the p‐HBA broke down, disappearing after 12 h of incubation in non‐sterile soil. Both p‐HBA and p‐HBAL were stable under sterile soil conditions for up to 24 h. The relative abundance of Proteobacteria was significantly inhibited. However, those of Acidobacteria, Chloroflexi, Verrucomicrobia and Cyanobacteria were increased by the p‐HBAL treatment. These findings suggest that allelochemicals from S. halepense might affect the bacterial community composition in the soil.

Regulation of photosynthetic material production by inter-root microbial extinction and metabolic pathways in sorghum under different nitrogen application patterns

“…With the increasing crop yield and fertilizer application, the impact of fertilizer application on the ecological environment of farmland has received much attention from researchers, especially the quality of soil environment and quality and safety of agricultural products caused by fertilizer application has attracted wide attention worldwide 12 , 13 . In this context, scholars have carried out experimental research on chemical fertilizer alternative technology, straw return, precision fertilizer application and formula fertilizer application, and agreed that chemical fertilizer alternative technology is the most effective, and the study shows that the combination of chemical fertilizer and organic fertilizer is an important means to solve the excessive use of chemical fertilizer, improve the soil environment and enhance crop yield 14 , 15 .…”