Response of Water Stress and Bacterial Fertilizer Addition to the Structure of Microbial Flora in the Rhizosphere Soil of Grapes Under Delayed Cultivation

Abstract

ABSTRACT The objectives of this study were to reveal the soil microbial structures in the rhizosphere soil of the delayed cultivation and to evaluate the effects of water stress and bacterial fertilizer on major bacteria. The experiment was conducted in 2019 in Yongdeng County, Gansu Province. Three treatments of water regulation were set, including the moderate water stress, mild water stress and adequate water supply treatment with the bacterial fertilizer added at the levels of no addition (0 g), small addition (75 g) and large addition (150 g), respectively. The results showed that the relative abundance of dominant species of soil microorganisms was significantly higher under sufficient water supply and mild water stress treatment than under moderate water stress treament. Under the mild water stress condition, the relative abundance of the most dominant species in each classification level sequentially decreased with the bacterial fertilizer added increasingly. Adding a small amount of bacterial treatment fertilizer to moderate water stress can improve the overall abundance of soil microbial communities during the growth period of new shoots. It was found that Proteobacteria, Bacteroidetes, Gemmatimonadetes, Actinobacteria, Firmicutes, Acidobacteria, Chloroflexi, Planctomycetes, Thaumarchaeota, Verrucomicrobia, and the other bacteria were the major bacterial phyla in the rhizosphere soil of delayed cultivation grapes, among, which Proteobacteria were the most dominant group. Therefore, adding a small amount of bacterial fertilizer under the mild water stress treatment can not only improve the diversity and richness of soil microorganisms during the fruit expansion period, but also significantly save water resources compared with the traditional irrigation regimes.