Phenolic acids alleviated consecutive replant problems in lily by regulating its allelopathy on rhizosphere microorganism under chemical fertiliser reduction with microbial agents in conjunction with organic fertiliser application

Abstracts Phenolic acids play a crucial role in regulating soil microecosystem functions, and their accumulation is a significant factor contributing to the problems associated with consecutive replant problems. Soil quality can be enhanced significantly by reducing chemical fertiliser usage and by incorporating bio-organic fertilisers. In this study, we designed two types of fertiliser reduction treatments, with reductions of 30 % and 50 %, supplemented with microbial agents and organic fertilisers, respectively. To investigate the effect of phenolic acids on the growth of perennial vegetables (edible lily) by regulating their allelopathic interactions with microorganisms in replanted soil under reduced fertiliser mode. The results indicated that these fertiliser reduction treatments led to improvements in soil physicochemical indices and reductions in total phenolic acid content. Furthermore, the treatments slowed the loss of soil microbial diversity and optimised microorganism structures, namely important functional bacteria (such as Proteobacteria phylum, the genus Sphingomonas, Bacillus, etc.) and endophytic fungi accumulated, whereas pathotrophic fungi and plant pathogenic fungi reduced. PICRUSt2 analysis suggested an enhancement in bacterial metabolism related to phenolic acid degradation. Correlation analyses highlighted that the allelopathic inhibition of total phenolic acid and some of its fractions (such as vanillin, benzoic acid, and cinnamic acid) on endophyte colonisation and plant autotoxicity, and allelopathic enhancement of Sphingomonas colonisation by phthalic acid, contributed to microorganism structure optimisation. Thus, phenolic acids influenced soil function by modulating their allelopathic effects on microorganisms. Reducing fertiliser by 30 %, supplemented with microbial agents and appropriate organic fertilisers, is an effective strategy to improve the yield and quality of lily bulbs. With the use of organic fertilisers and suitable microbial agents, this fertiliser mode can be effectively utilised to promote the sustainable production of economic perennial crops in the mountainous regions of northwestern China. •Proteobacteria and Sphingomonas could be considered indicators of soil health under a continuous cropping system.•30 % chemical Fertiliser reduction with microbial agents can enhance the degradation metabolic pathway of phenolic acid substances by bacteria.•Under the 30 % chemical fertiliser reduction mode, the reducing t