Rhizosphere Fungal Communities Under Conservation Tillage Shift in Response to Plant Growth.

Conservation tillage represents an extensively used agriculture practice in northern China that alters soil texture and nutrient conditions, causing changes in the soil microbial community. However, how conservation tillage affects both of rhizosphere and bulk soil fungal community during plant growth remains unclear. Our present study was intended to investigate the effect of 6-year conservation (chisel plough, zero) tillage and conventional (plow) tillage on the soil rhizosphere fungal community during wheat growth using high-throughput sequencing of 16S rRNA genes and quantitative PCR. We showed that soil fungal alpha diversity was significantly higher under zero till treatments during tillering, while tillage had no significant effect during the flowering stage. Instead, the alpha diversity was significantly different between rhizosphere and bulk soils during flowering, with the highest diversity seen in the bulk soil. This was also reflected in the phylogenetic structure of the communities, which showed that the communities in the rhizosphere underwent a greater shift from tillering to flowering compared to bulk soil communities. In general, less variation in community structure was observed under zero tillage compared to plow and chisel plow treatments. Changes of relative abundance fungal order (Capnodiales, Pleosporales, Xylariales) contributed most to the dissimilarities observed. Structural equation models (SEM) revealed that the soil fungal community under three tillage regimes were likely influenced by the changes in soil properties associated with plant growth. This study suggested that (1) the difference of nutrients resources between rhizosphere and bulk soil can select for different types of fungi thereby increasing community variation during plant growth; (2) tillage can alter the amount of variability in fungal communities, with zero tillage promoting more stable communities. This work suggests that long-term changes in tillage regimes may result in unique soil fungal ecology that may have influences on other aspects of soil functioning (e.g. decomposition).