Soil Microbial Communities Altered by Titanium Ions in Different Agroecosystems of Pitaya and Grape

Titanium (Ti) is an element beneficial to plant growth. Application of titanium to roots or leaves at low concentrations can improve crop yield and performance. However, the effect of titanium ions on the bulk soil microbial community of planted crops remains unclear. This study aimed to explore the effects of titanium on soil bacterial and fungal communities. Field surveys were conducted to determine the effect of titanium ions on bulk soil microbial communities in pitaya and grape plantations of Panzhihua and Xichang areas, respectively. Full-length 16S rRNA and internal transcribed spacer (ITS) amplicon sequencing were performed using PacBio Sequel to further explore the composition and structure of soil microbiota. The application of titanium ions significantly altered the composition and structure of soil microbiota. Root irrigation with titanium ions in pitaya gardens reduced the diversity of soil fungi and bacteria. However, the decline in bacterial diversity was not statistically significant. Meanwhile, foliar spray of titanium ions on grapes greatly reduced the soil microbial diversity. The bulk soil microbiota had a core of conserved taxa, and titanium ions significantly altered their relative abundances. Furthermore, the application of titanium increased the interaction network of soil fungi and bacteria compared with the control group. Thus, titanium ions potentially improve the stability of the soil microbial community. IMPORTANCE Pitaya and grape are important cash crops in the Panzhihua and Xichang areas, respectively, where they are well adapted. Titanium is a plant growth-promoting element, but the interaction between titanium and soil microorganisms is poorly understood. Titanium ions are still not widely used for growing pitaya and grape in the two regions. Thus, we investigated the effects of titanium ions on soil microbial communities of the two fruit crops in these two regions. Microbial diversity decreased, and the community structure changed; however, the addition of titanium ions enhanced cooccurrence relationships and improved the stability of the community. This study provides a basis for the importance of titanium ion application in crop cultivation.