Effects of corn stalk biochar on soil physicochemical properties and fungal community structure in the rhizosphere of Gaillardia pulchella Foug.

【Objective】To clarify the effects of corn stalk biochar treatment on the changes of environmental factors such as soil nutrient content, enzyme activity and rhizosphere fungus community in Gaillardia pulchella Foug. and its mechanism, and provide theoretical basis for the utilization of corn stalk.【Method】Applied 20, 40, 60 and 80 g/kg corn stalk biochar into the soil of potted G. pulchella. Used no corn stalk biochar treatment as control(CK), and measured contents of available nutrients(available phosphorus, available potassium, alkali-hydrolyzable nitrogen and organic matter) and the activities of catalase(CAT) and urease in rhizosphere soil of G. pulchella during the full bloom period. Highthroughput sequencing technology was used to determine the fungal community diversity in rhizosphere soil, and the correlation between the physical and chemical properties of the rhizosphere soil and soil fungal community structure under the action of corn stalk biochar was analyzed.【Result】Compared with CK treatment, applying 20-60 g/kg corn stalk biochar into the soil could significantly increase the content of available phosphorus in the rhizosphere soil of G. pulchella(P<0.05, the same below), and extremely significantly increase available potassium, alkaline nitrogen and organic matter content(P<0.01, the same below). In terms of soil enzyme activity, the application of 20-80 g/kg corn stalk biochar in the soil had no significant effect on CAT activity(P>0.05, the same below). Application of 40 g/kg corn stalk biochar extremely significantly increased urease activity, but application of 80 g/kg corn stalk biochar extremely significantly reduced urease activity. That was to say, corn stalk biochar could effectively change the physical and chemical properties of the rhizosphere soil of G. pulchella, and the effect of 40 g/kg was the best. The application of corn stalk biochar could regulate the fungal community structure in the rhizosphere soil of G. pulchella, and the relative abundance of fungal species at 40 g/kg was higher, and the effect of biochar was the most obvious. At the level of phyla classification, Ascomycota was the absolute predominance in the structure of the fungal flora in the rhizosphere soil of the corn stalk biochar treatment, followed by Basidiomycota, Zygomycota, Chytridiomycota and Glomeromycota. At the level of family classification, the dominant family of bacteria were six families of Ascomycota:Chaetomiaceae, Microascaceae, Nectriaceae, Lasiosphaeriaceae, Ascomycoceae, Coniochaetaceae, and Mortierellaceae of the phylum Mortierellaceae. In the all six dominant bacteria families(Lasiosphaeriaceae, Microascaceae, Nectriaceae, Ascomycoceae, Mortierellaceae and Coniochaetaceae) in rhizosphere soils, the relative abundance of each corn stover biochar treatment was higher than that of CK treatment. The physicochemical characteristics of the rhizosphere soil of G. pulchella were closely related to the relative abundance of Ascomycota and Zygomycota, Ascomycocaceae, Mortierellaceae and Chaetomium.【Conclusion】Corn stalk biochar can activate the physicochemical properties and enzyme activity of the rhizosphere soil of G. pulchella, change the structure of soil fungi community, and improve soil fertility. Among them, 40 g/kg corn stalk biochar has the best effect, and can be promoted and applied in production.