Effects of Micro-sprinkler Irrigation under Plastic Film on Bacterial Community and Enzyme Activity of Tomato Rhizosphere Soil in Greenhouse

The response mechanism of bacterial community and enzyme activity in rhizosphere soil of vegetables under irrigation measures for new water-saving micro-sprinkling irrigation under plastic film (MSPF) in facility agriculture is unclear. Therefore, a completely randomized experimental design was used to study the effects of different irrigation frequencies (F, F1: irrigation frequency 3d, F2: irrigation frequency 5d, F3: irrigation frequency 7d ) and irrigation amount (I, I1: 0.7 Epan, where Epan is the cumulative evaporation of Φ20 cm standard pan, I2: 1.0 Epan, I3: 1.2 Epan ) on bacterial community and enzyme activity in rhizosphere soil of greenhouse tomatoes. The results showed that with the increase of F or I, the total number of soil bacteria in spring tomatoes and autumn tomatoes increased first and then decreased at the OTUs classification level. The irrigation frequency of 5 d can optimize the bacterial community, increase the abundance of functional genes related to nitrogen and phosphorus metabolism of soil bacteria, and increase the activity of nitrogen, carbon and phosphorus metabolism-related enzymes. With the increase of I, the diversity of soil bacterial community structure increased first and then decreased. The 1.00Epan under MSPF helps to increase the abundance of nitrogen and phosphorus metabolism functional genes of soil bacteria, and ensure that tomato rhizosphere soil has high nitrogen, carbon and phosphorus metabolism-related enzyme activities. With the increase of F or I, the yield of tomato increased first and then decreased, among which the I had the greatest influence on the yield of tomato. If the I is increased by 1.00%, the yield of tomato increases by at least 39.24%. There was a positive interaction between soil bacterial community, soil enzyme activity and yield of greenhouse tomatoes under the control of MSPF irrigation measures. Considering comprehensively, the F2I2 combined irrigation mode is recommended for MSPF in Northwest China.