生物炭对西瓜连作土壤真菌群落结构和功能类群的影响

为明确生物炭施入后对西瓜连作土壤真菌群落结构及功能类群的长期影响,以西瓜成熟期根区土壤为研究对象,借助Illumina NovaSeq高通量测序技术和 FUNGuild平台,探究不同用量（7.5、15.0和30.0 t·hm^-2）生物炭施用3 a后西瓜连作土壤真菌群落组成、多样性及功能的差异,并分析土壤环境因子与真菌群落结构间的关联性.结果表明,添加生物炭3 a后提高了土壤pH、有效磷、速效钾、全氮、有机质和阳离子交换量,降低了土壤碱解氮含量.生物炭的施用改变了西瓜连作土壤真菌群落结构,提高了土壤真菌的丰富度和多样性.所有土壤样本共获得922个OTU,子囊菌门、担子菌门、被孢菌门、壶菌门和球囊菌门为优势真菌类群,占土壤真菌群落的85.70 %~92.45 %,生物炭的施入降低了子囊菌门和担子菌门的相对丰度,增加了被孢菌门和球囊菌门的相对丰度；属水平上,随着生物炭的施用,被孢霉属和囊根壶菌属的相对丰度增加,而镰刀菌属相对丰度降低.Mantel检验分析发现,速效钾、碱解氮、有机质和pH是影响土壤真菌群落结构的主要环境因子.真菌主要营养类型为腐生营养型、病理营养型和共生营养型,中、高剂量生物炭处理显著降低了土壤中病理营养型真菌的相对丰度,显著增加了共生营养型真菌的相对丰度.综上,生物炭施用3 a后可改变西瓜连作土壤理化性质,促进土壤真菌群落结构和功能类群向健康有益方向发展.

Effects of Biochar Application on the Structure and Function of Fungal Community in Continuous Cropping Watermelon Soil

This study was conducted to clarify the long-term effects of biochar application on the structure and function of the fungal community in continuous cropping watermelon soil. Taking watermelon root soil as the research object, Illumina NovaSeq high-throughput sequencing and FUNGuild platform were used to analyze the differences in soil fungal community composition, diversity, and function after 3-year biochar additions of 7.5, 15.0, and 30.0 t·hm^-2 and to explore the correlation between soil environmental factors and fungal community structure under the control of biochar. The results showed that compared to that in the absence of biochar (control), the soil pH, available phosphorus, available potassium, total nitrogen, organic matter, and cation exchange capacity increased, but available nitrogen decreased with biochar addition. High-throughput sequencing results showed that biochar amendment improved the fungal community structure in continuous cropping watermelon soil and increased the richness and diversity of soil fungi. A total of 922 OTU were obtained from all soil samples, and the species annotation results indicated that the dominant fungal groups were Ascomycota, Basidiomycota, Mortierellomycota, Chytridiomycota, and Glomeromycota, with these phyla accounting for 85.70 %-92.45 % of the total sequences.The relative abundance of Ascomycota and Basidiomycota decreased, whereas the abundance of Mortierellomycota and Glomeromycota increased with biochar addition.At the genus level, the application of biochar increased the relative abundance of Mortierella and Rhizophlyctis but decreased the abundance of Fusarium. The Mantel test showed that soil available potassium, available nitrogen, organic matter, and pH were the main environmental factors leading to the shift in the soil fungal community composition.The functional prediction with FUNGuild showed that the many nutrient types among the different treatments were saprotrophic, pathotrophic, and symbiotrophic. The relative abundance of pathotrophs significantly decreased, but the abundance of symbiotrophs significantly increased with the medium and high doses of biochar treatment. In conclusion, the application of biochar changed the soil physicochemical properties, promoted the development of soil fungal community structure and functional groups in a healthy and beneficial direction, and improved the quality of continuous cropping watermelon soil.