大盘山榧幼苗根际土壤真菌群落及养分限制与其长势的关系OA

Rhizosphere fungi play an important role in helping plants absorb nutrients and maintaining normal growth of trees.To clarify the relationship between the rhizosphere fungal community,nutrient limitation and seedling growth of Torreya dapanshanica,the artificially cultivated T.dapanshanica of different growth performance was subjected to the research.High-throughput sequencing technology was used to determine the composition and trophic modes of the rhizosphere soil fungal community of T.dapanshanica sapling with different growth performance.Meanwhile,the physicochemical properties of the rhizosphere soil and the stoichiometric characteristics of soil enzymes of the two kinds of soil were analyzed.The results showed that:(1)The amounts of soil organic carbon,ammonium nitrogen,available phosphorus,and total phosphorus in the rhizosphere of advantaged trees were significantly higher than those of disadvantaged trees.Analysis of soil enzyme stoichiometric ratios revealed that disadvantaged trees were subjected to nitrogen limitation.(2)The Chao1 index and Shannon index of the rhizosphere soil fungal community in advantaged trees were significantly higher than that in disadvantaged trees.And non-metric multidimensional scaling(NMDS)analysis showed that the rhizosphere soil fungal compositions of T.dapanshanica saplings with different growth performance could be clearly separated.(3)The results of fungal trophic modes analysis indicated that,compared with the rhizosphere of disadvantaged trees,the relative abundance of symbiotrophic fungi in the rhizosphere soil of advantaged trees was significantly higher,while the relative abundance of pathotrophic fungi was significantly lower.Moreover,plant height was significantly positively correlated with the relative abundance of rhizosphere symbiotrophic fungi and significantly negatively correlated with the relative abundance of pathotrophic fungi.(4)Canonical correspondence analysis showed that the main factors affecting the rhizosphere fungal composition of advantaged trees were soil ammonium nitrogen and available phosphorus contents,and the rhizosphere fungal composition was positively correlated with soil phosphatase activity;whereas the rhizosphere fungal community of disadvantaged trees was greatly affected by nitrogen limitation.In summary,the advantaged trees had a higher abundance of symbiotic fungi in the rhizosphere and a more adequate supply of phosphorus,which was conducive to maintaining their good tree performance;The abundance of pathotrophic fungi in the rhizosphere soil of disadvantaged trees was relatively high,with the presence of soil nitrogen limitation.Therefore,the combined application of nitrogen fertilizer and organic fertilizer could alleviate the rhizosphere nutrient limitation of disadvantaged trees and reduce the abundance of pathotrophic fungi.This study provides a basis for maintaining the good growth and conservation of rare plants through rhizosphere regulation under adverse site conditions.