Analysis of characteristics and influencing factors of plant ash on soil fungal community of Morchella

Abstract :[ Objective ] To analyze the characteristics of fungal community and its influencing factors with different addition amounts of plant ash in Morchella esculenta cultivation soil, so as to provide scientific basis for soil improvement, soil health enhancement and prevention and control of soil-borne diseases by using plant ash. [ Method ] Taking Morchella liumeiensis as the experimental material, the lllumina Nextseq PE300 high-throughput sequencing technology combined with statistical analysis method was used to analyze the relative abundance, Alpha diversity index, Beta diversity, inter-group differences, functional prediction and correlation between microbial community and physical and chemical properties of Morchella cultivated soil with 1 %, 3 % and 5 % ash addition in primordium period ( 40 days after sowing ). Finally, the microbial community structure and functional characteristics were revealed by multivariate statistical methods and visualization techniques. [ Result ] The results of diversity analysis showed that the physical and chemical properties of soil and the structure of fungal community changed significantly under different addition amounts of plant ash. With the increase of plant ash addition, the pH value and potassium ions increased significantly, while calcium ions decreased significantly. The addition amount of plant ash and nitrogen conversion showed a threshold effect : the accumulation of nitrate nitrogen was promoted in the range of 0 % -3 %, but the conversion rate decreased at 5 % addition amount, and the difference of fungal community was the most significant at 5 % addition amount. The functional prediction showed that the excessive addition of plant ash led to the change of fungal nutritional type, and the pathological nutritional type increased significantly at 5 % addition. The correlation analysis between physicochemical properties and microbial community showed that the structural reorganization under 5 % addition was related to the imbalance of flora caused by excessive soil pH and potassium ions. In addition, the beneficial fungi such as Moriterellomycota and Mortierella increased at 1 % and 3 %, and decreased at 5 %. Mortierella was significantly positively correlated with exchangeable calcium. The overall trend of Penicillium and Aspergillus decreased after the addition of plant ash, which was positively correlated with the increase of ammonium nitrogen and calcium ions. [ Conclusion ] The application of plant ash could have a positive effect on the growth of Morchella through the change of microbial community. The decrease of Penicillium and Aspergillus indicated that plant ash could inhibit some pathogenic fungi by reducing ammonium nitrogen and calcium ions. However, the pathotrophic type increased significantly at 5 % addition, the beneficial fungi such as Moriterellomycota and Mortierella decreased, and the ammonium nitrogen conversion rate decreased. Therefore, precise gradient addition of plant ash is needed to regulate the soil microenvironment. Explore the optimal range. The study also showed that the addition of plant ash led to the loss of calcium ions, and calcium sources such as gypsum could be supplemented preferentially to promote growth.