The differences between mycorrhizal fungi species and dominant flora of Torreya grandis in Guizhou were explored, and the fungal community composition in the root and rhizosphere soil of Torreya grandis in four regions was compared, in order to explore the diversity and community structure of the fungi of Torreya grandis roots.

The Torreya grandis communities with yellowing phenomenon in Guiyang, Xiuwen County, Zheng'an County and Wuchuan Gelao and Miao Autonomous County were selected as the research objects. The root system and rhizosphere soil of Torreya grandis were collected for high-throughput sequencing. The fungal diversity and the difference in the community structure of root systems were analyzed, and the differences in fungal structures between root and rhizosphere soils were compared in the four regions.

The results showed that there were 558253 effective sequences in the root system and 568821 effective sequences in the rhizosphere soil of Torreya grandis. The root-rhizosphere fungi of yellow Torreya grandis belonged to 5 phyla, 15 classes, 23 orders, 33 families, 46 genera and 61 species. The dominant fungal phyla were Ascomycota, Mortierellomycota and Basidiomycota, which accounted for more than 90% of the total abundance of the whole fungal community. From the perspective of fungal population structure, Ascomycota was the most dominant phylum among the endophytic fungi in the four regions, Mortierellomycota was the most dominant phylum among the rhizosphere soil fungi, and there were some differences between endophytic roots and the rhizosphere. Among all regions, Mortierellomycota and Mortierellomycotes in Wuchuan County and Zheng'an County were relatively abundant, while Mortierellomycota and Mortierellomycotes in Xiuwen County and Guizhou Botanical Garden were relatively low. Wuchuan County and Zheng'an County shared highly similar fungal structures, and Xiuwen County and Guizhou Botanical Garden had highly similar fungal structures, which were different from the fungal structures of Wuchuan County and Zheng'an County. There were 2 485 fungal OTUs in the Torreya grandis samples from the four regions, including 1 198 fungal OTUs in rhizosphere soil and 1 287 fungal OTUs in root endophytic fungi.

It is concluded that the rhizosphere microbial community structure is influenced not only by plant health, but also by different regions, and there are obvious differences in the composition and structure of fungal populations in the root system of yellow Torreya grandis in the four regions.

This study aimed to investigate the impact of nitrogen (N), phosphorus (P), and potassium (K) elements on the early-stage growth of Ormosia hosiei saplings during afforestation and identify the optimal fertilization formula for enhancing their growth.

2 a O. hosiei saplings were selected as the material, and a large container was used to simulate the afforestation habitat. The “3414” incomplete block orthogonal design was employed to fertilize nitrogen, phosphorus, and potassium. The fertilizers used were urea, superphosphate, and potassium chloride, with their active components being N (46%), P₂O₅ (22.6%), and K₂O (52.1%), respectively. The height, ground diameter, root system, and biomass of O. hosiei saplings were measured under different nitrogen, phosphorus, and potassium treatments.

The rational application of N, P, and K elements significantly promoted the growth of O.hosiei saplings. Among the 14 treatments, the O. hosiei saplings treated with T7 (N2P3K2) exhibited the most favorable growth response. Compared to the control, the seedling height increment, ground diameter increment, and total biomass increased by 148.64%,117.20%, and 87.80%, respectively, with the root development being the most robust. The effects of the three elements, under each treatment, followed the order of P > N > K, highlighting the importance of phosphate fertilizer for O. hosiei growth. Different equations were derived to represent the individual, binary, and ternary effects of biomass and nitrogen, phosphorus, and potassium fertilization. The results showed a decreasing trend in the application effect of nitrogen, phosphorus, and potassium, with the highest interaction effect observed for NP fertilizer. Furthermore, the combined application of all three elements yielded significantly better results than any two-element combinations. The membership function analysis identified T7 as the optimal fertilization treatment group.

The treatment of T7 (N2P3K2) can significantly improve the height, diameter, root, and total biomass of 2 a O. hosiei seedlings. The fertilization model showed that the best fertilization formula was recommended by N 42.917 g, P₂O₅ 70.565 g, and K₂O 24.439 g for each O. hosiei eedling, with an appropriate fertilization ratio of nitrogen, phosphorus, and potassium at 1:1.64:0.56.