Response of grass interplanting on bacterial and fungal communities in a jujube orchard in Ningxia, northwest China.

Orchard grass is an important soil management method that improves pest resistance in fruit trees and it reduces the usage of chemical fertilizer to protect the environment. In this study, we investigated the bacterial and fungi communities in the rhizosphere of Ziziphus jujuba Mill cv. 'lingwuchangzao' by high-throughput sequencing to test the effects of different sward types. The soil organic matter, available phosphorus, available potassium, and total nitrogen contents were higher with cleared tillage compared with the other planting grass treatments. Ascomycota, Basidiomycota, and Mortierellomycota were the dominant fungal groups. Most of the soil nutrient levels were lower in the treatments with grass (except for planting with ryegrass and pea grass) than cleared tillage, but there were no significant differences in the bacterial and fungi diversity. pH and total phosphorus were the main contributors to variations in the bacterial communities. The variations in the fungal communities were mainly attributed to the soil nutrient levels. The changes in the titratable acids and vitamin C contents were clearly correlated with the dynamics of the bacterial and fungi communities. Network analysis showed that 60% of the bacteria had close connections with fungi, including the dominant bacteria comprising Proteobacteria, Actinobacteria, and Bacteroidetes. Our findings demonstrated that different types of grass treatments affected the abundances of microbes rather than their composition.