Abstract:

To explore the impact of organic fertilizer on the physiological growth of flax and the rhizosphere bacterial communities,and to investigate green high-yield cultivation techniques for flax in dryland,a field experiment was conducted using Baxuan No.3 as the material.The study examined the effects of four different fertilization treatments(T0:no application; T1:low quantity of cow manure; T2:medium cow manure; T3:high quantity of cow manure)on the physiological growth changes,nitrogen utilization,dry matter accumulation,and the diversity,community composition,co-occurrence networks,and metabolic pathways of the rhizosphere bacteria of flax,as well as discussing the environmental factors driving the differences in bacterial communities.The results showed that the T3 treatment resulted in higher flax production. Compared to the control, this fertilization condition also had the highest indicators for plant height, capsule fruit number per plant, thousand-grain weight, and nitrogen use efficiency, which form the physiological basis for stable yield following the application of organic fertilizer.The application of organic fertilizer significantly affected the diversity and richness of the rhizosphere soil bacteria of flax,and there were significant differences in the structure of the rhizosphere bacterial community.The population structure of the rhizosphere bacteria of flax was influenced by organic matter,total nitrogen,and available phosphorus.The dominant flora in the rhizosphere of flax was the same across different treatments,but the relative abundance of each dominant flora varied significantly.The rhizosphere of flax was dominated by the phyla Proteobacteria,Actinobacteria,Acidobacteria,Chloroflexi,and Bacteroidetes.The relative abundance of Proteobacteria and Actinobacteria increased with the increase of organic fertilizer treatments,while that of Acidobacteria decreased with the increase of organic fertilizer treatments.WGCNA analysis identified 15 co-expression modules,with the Red and Pink modules showing a significant positive correlation with organic matter content.The application of organic fertilizer increased the complexity of the bacterial network,and seven key OTUs were identified through combined WGCNA analysis.In conclusion,the application of organic fertilizer promoted the growth of flax and altered the structure and network complexity of the bacterial community in the rhizosphere soil of flax.

Key words: Oilseed flax, Organic fertilizer, Rhizosphere microbiome, Co-network construction, Bacterial diversity