Impact of Intercropping on the Diazotrophic Community in the Soils of Continuous Cucumber Cropping Systems

Abstract

Diazotrophs are important soil components that help replenish biologically available nitrogen (N) in the soil and contribute to minimizing the use of inorganic N fertilizers in agricultural ecosystems. However, there is little understanding of how diazotrophs respond to intercropping and soil physicochemical properties in cucumber continuous cropping systems. In this study, using the nifH gene as a marker, we have examined the impacts of seven intercropping plants on diazotrophic community diversity and composition compared to a cucumber continuous cropping system during two cropping seasons. The results showed that intercropping increased the abundance of the nifH gene, which was negatively correlated with available phosphorous in the fall. Diazotrophic diversity and richness were higher in the rape–cucumber system than in the monoculture. Multivariate regression tree analysis revealed that the diversity of the diazotrophic communties was shaped mainly by soil moisture and available phosphorous. Skermanella were the dominant genera in all of the samples, which increased significantly in the mustard–cucumber system in the fall. There was no effect of intercropping on the structure of the diazotrophic community in this case. Non-metric multidimensional scaling analysis showed that cropping season had a greater effect than intercropping on the community structure of the diazotrophs. Overall, our results suggest that intercropping altered the abundance and diversity rather than the structure of the diazotrophic community, which may potentially affect the N fixation ability of continuous cropping systems.

Response of Cucumis sativus to Neighbors in a Species-Specific Manner

“…Continuous monoculture adopted in the cultivation of Cucumis sativus , an important horticultural crop, has caused problems such as yield reduction and quality deterioration [ 32 , 33 ]. Intercropping has proved to be a sustainable way to solve these problems [ 34 ].…”

Soil-plant-microbiota interactions to enhance plant growth

“…Additionally, the authors also noted that the abundance of the nifH gene was increased when soybean and corn were cropped in rotation compared to continuous cropping. Similarly, Gao et al (2021) showed that rape-cucumber intercropping increased the abundance of the nifH gene, diazotrophic diversity, and richness, which were higher than in the monoculture. However, cropping season had a more significant effect than intercropping.…”