Responses of Bacterial Community, Root-Soil Interaction and Tomato Yield to Different Practices in Subsurface Drip Irrigation

The objective of this study was to reveal the regulatory mechanisms underlying the soil bacterial community of subsurface drip irrigation (SDI). The effect of different buried depths of drip tape (0, 10, 20, 30 cm) on the soil bacterial community in a tomato root-zone was investigated using high-throughput technology. Furthermore, the mutual effects of root growth, tomato yield and soil bacterial community were also analyzed to explore the response of root-soil interaction to the buried depth of drip tape. The results indicated that SDI (i.e., 10, 20 and 30 cm buried depths of drip tape) changed the soil bacterial community structure compared to surface drip irrigation (a 0 cm buried depth of drip tape). SDI with a 10 cm buried depth of drip tape significantly reduced the relative abundances of Proteobacteria, Chloroflexi, Gemmatimonadetes, Acidobacteria, Firmicutes and Planctomycetes, but significantly increased the relative abundances of Actinobacteria, Candidate_division_TM7 and Bacteroidetes. SDI of 20 and 30 cm buried depth significantly decreased the relative abundances of Roteobacteri, Actinobacteria and Planctomycetes, however, increased the relative abundances of Chloroflexi, Gemmatimonadetes, Acidobacteria, Firmicutes, Candidate_division_TM7 and especially some trace bacteria (for example Nitrospirae). Furthermore, under 20 cm or 30 cm of buried depth, the abundances of nitrogen metabolism and phosphonate and phosphinate metabolism based on the PICRUSt (Reconstruction of Unobserved States) method were significantly improved as well as soil porosity and root forks at 0-10 cm. These changes strengthened root-soil interaction and improved tomato yield per plant by 22.47% and 19.38% under 20 cm and 30 cm of buried depth, respectively, compared to surface drip irrigation. Therefore, the responses of bacterial community and root-soil interaction to drip tape buried depth of 20 cm and 30 cm are proven to be beneficial for the increasing of tomato production.