[Effects of addition of sorghum stubble rhizosphere soil on growth and rhizosphere microbes of continuous cropping cucumber].

We explored the effects of addition of sorghum stubble rhizosphere soil on the growth of continuous cropping cucumber and rhizosphere microbial community in a pot experiment. The diffe-rences in soil bacterial and fungal community composition were analyzed with fluorescence quantitative PCR and high-throughput sequencing technology. There were four treatments: CK (no fertilization), T1(fertilizer only), T2(optimized fertilization), and T3(optimized fertilization + rhizosphere soil of sorghum stubble). The results showed that compared with other treatments, T3 promoted the growth and development of cucumber, and increased the abundance of 16S rRNA and ITS rRNA genes in soil. Compared with the T1 treatment, T2 and T3 significantly increased the richness and diversity of bacterial communities. There was no significant difference in fungal community richness and diversity among different treatments. Adding rhizosphere soil of sorghum stubble changed the composition of bacterial and fungal communities at both phylum and genus levels. For bacteria, it increased the abundances of Acidobacteria and Bacteroides, but decreased that of Proteobacteria, Firmicutes, Nitrospira and Bacillus. For fungi, it increased the abundance of Basidiomycota, Trichoderma and Pseudurotium, but decreased that of Fusarium and Metarhizium. Results of redundancy analysis showed that soil nitrate and organic matter were the key factors affecting the difference of bacterial and fungal community composition, respectively. In conclusion, addition of sorghum stubble rhizosphere soil improved the total abundance of soil microorganisms and bacterial diversity for continuous cropping cucumber. It increased the abundance of beneficial bacteria Trichoderma, reduced that of pathogenic Fusarium, and maintained the survival rate of cucumber, thus provided a feasible solution for alleviating the barriers for the continuous cropping of cucumber.