Effects Of Karst Soil Heterogeneity And AM Fungi On Growth And Nutrients Utilization Of Bidens Pilosa

Arbuscular mycorrhiza(AM)is a symbiont formed by plant roots and AM fungi.This symbiont mainly depends on the supply of plant photosynthetic carbon source and the absorption of soil nutrients through its ectomycorrhiza,which affects the plant soil ecological process.Karst landforms are very heterogeneous in space,and their heterogeneous shallow soil and exposed rock crisscross distribution,seriously limiting the growth of plants and nutrient intake.Previous studies have shown that non resource factors such as soil heterogeneous patches and particle size are important factors that affect the growth and distribution of individual plants and even populations.However,how do adaptive plants survive in highly heterogeneous karst environments? It is not clear whether AM fungi,widely distributed in heterogeneous habitats,can effectively regulate heterogeneous patch soil and affect plant survival and nutrient uptake? Therefore,in this study,Bidens pilosa a suitable herb in Karst,was selected as the research object,Construction of Spatial Heterogeneity and Soil Matrix Microecosystems by Inoculation,Through AM fungal treatment(inoculation,M+;non-inoculation,M-)and soil spatial heterogeneity treatment(Homogeneity patch,HO;Heterogeneous small patch,SP;Heterogeneous large patch,LP),as well as soil matrix heterogeneity treatment(Homogeneous patch soil matrix,HO;Small patch soil matrix,SS;Small patch of lithosol mixed matrix,SL;Large patch soil matrix,LS;Large patch of lithosol mixed matrix,LL),the karst adaptive plant Bidens pilosa was planted,After 3 months of plant growth,seedling height,ground diameter,biomass growth index,plant nutrient and soil physical and chemical properties index were measured,analysis of plant growth and nutrients utilization characteristics from the perspective of spatial heterogeneity and matrix heterogeneity regulated by AM,The main results are as follows:(1)AM treatment significantly increased the mycorrhizal colonized rate,seedling height,ground diameter,root phenotype and production of Bidens pilosa.There were significant differences in population growth characters among different patch heterogeneity treatments,under M+ treatment,the population mycorrhizal colonized rate and ground diameter in SP weresignificantly higher than that in HO;The population height was significantly higher in LP than in HO;the root length,tips and furcations in HO were significantly higher than those in SP and LP;The total population production and leaf production were significantly higher in SP than in HO treatment.;Under M-treatment,there was no significant difference in the growth indexes of different patch spatial heterogeneity treatments.(2)AM treatment significantly increased the N,P and K acquisitions of Bidens pilosa population.There were significant differences in population nutrients acquisitions among different patch heterogeneity treatments,under M+ treatment,the total N acquisitions of population was significantly different among HO,SP and LP,and SP treatment was the maximum,the N acquisitions of leaves in SP was significantly higher than that in HO,LP;The acquisitions of total P and leaf P of plant population in SP was significantly higher than that in HO,LP,and there was no significant difference between HO and LP;The acquisitions of total K and leaf K of plant population were higher in SP,than that in HO and LP,only SP and LP had significant difference.Under M-treatment,there was no significant difference in population nutrients acquisitions of different patch spatial heterogeneity treatments.(3)AM treatment reduced the contents of soil N and K in different degrees,and significantly increased the contents of AP in SP and LP.There were significant differences in soil nutrients contents in different patch heterogeneity treatments,under M+ treatment,there was no significant difference in the TN contents of soil among the HO,SP and LP;The TP contents of soil was significantly higher in LP treatment than in HO;The contents of TK in LP was significantly higher than that in SP.Under M-treatment,the contents of soil TN and AN in SP and LP were higher than that in HO,The contents of TK in LP was significantly higher than that in HO.(4)AM treatment significantly increased the root mycorrhizal colonized rate,seedling height,ground diameter,root characteristics and biomass of Bidens pilosa.There were significant differences in plant growth characters among different matrix heterogeneity treatments,under M+treatment,the mycorrhizal colonized rate of plants and the hyphal density of soil in SL were significantly higher than those in HO,SS and LS;The plant height and ground diameter were significantly higher in LL than in SS and LS;The length,furcations and tips of root in HO were significantly higher than those in SS,LS,SL and LS;The total biomass and leaf biomass of plant in SL and LL were significantly higher than that in HO,SS and LS,and HO was also significantlyhigher than that in SS and LS.Under M-treatment,there was no significant difference in plant growth indexes of different soil matrix treatments.(5)AM treatment significantly increased N,P,K acquisitions of Bidens pilosa.There were significant differences in plant nutrients acquisitions among different matrix heterogeneity treatments,under M+ treatment,the acquisitions of total N and stem and leaf N in HO,SS,LS and SL were significantly different,among which SL was the maximum and LS was the minimum,and HO was significantly higher than SS and LS;The acquisitions of total P and leaf P in SL and LL treatment were significantly higher than that in HO,SS and LS,and HO was also significantly higher than that in SS and LS,SL was the maximum;The acquisitions of total K and leaf K in SL and LL were significantly higher than that in HO,SS and LS,and HO was significantly higher than that in SS and LS.There was no significant difference between HL and SL.Under Mtreatment,there was no significant difference in plant nutrients acquisitions of different soil matrix treatments.In general,under the treatment of soil heterogeneity,AM fungi can promote the growth of plant population and individual,significantly improve the phenotypic growth index and the acquisitions of nitrogen,phosphorus,potassium and other nutrients,and effectively regulate the distribution proportion of nutrients in plants,reduce the content of nitrogen and potassium in soil,and improve the contents of AP in soil.Under the treatment of AM fungi,soil heterogeneity treatment had a significant effect on plant growth,mainly manifested by the significant difference between the heterogeneity treatment,In terms of population level,the heterogeneous small patches effectively regulate plants growth and N,P,K nutrients accumulation through AM fungal action.In terms of individual plants,the heterogeneous matrix increase the biomass and nutrients accumulation of plants through the action of AM fungi,Among them,the heterogeneity matrix under the small patch can promote the nutrients accumulation of N,P,K.Under the treatment of uninoculated AM fungi,soil heterogeneity had no significant effect on the growth index and acquisitions of plant population and individual.