Effects Of Acide-Aluminum Stress And Mycorrhizal Fungi Inoculation To Seedling Colonization Of Picea Schrenkiana

The Picea spruce forest of Tianshan Mountains soil is acidic?pH<5.5?,which causes the concentration of active Aluminium in soil increased easily,and the growth of mycorrhizal fungi and plants is inhibited.Mycorrhizal fungi are an important component of forest ecosystem,and are the main factors to maintain plant biodiversity and ecosystem functions.They can increase plant and tree diversity in the ecosystem.The excellent mycorrhizal fungi can promote the growth of trees,enhance the resistance to stress and promote nutrient uptake after mycorrhizal fungi and trees form mycorrhizal fungi.Therefore,it is important to study the mechanism of Aluminium resistance of mycorrhizal fungi for the conservation of Natural Spruce Forests in Tianshan Mountains.In this paper,five mycorrhizal fungi of Simplicillium sp.Si,Mortierella elongate Me,Trichoderma spp.Tr,Phialocephala Ph and Stachybotrys chartarum Sc isolated from the roots of Picea schrenkiana in Tianshan Mountains were used as test materials,divided into three part:?1?Six Al³⁺concentration gradients(0?CK?,0.2?Low Aluminum?,0.4?Medium and low Aluminum?,0.6?Medium Aluminum?,0.8?Medium and High Aluminum?,1.0?High Aluminum?mmol·L^-1)and five pH conditions?4.5,5.0,5.5,6.0,6.5?were separately set,determination of the diameter of the hyphae of the test strain and other indicators;?2?The test material was set up in a single pure culture of PDA liquid medium at a pH of 5.5 to set three Al³⁺concentration gradient controls?CK?,low Aluminum(0.2 mmol·L^-1),and high Aluminum(1.0 mmol·L^-1),the effects of changes in activeAluminum concentration on the biomass,organic acid secretion,and N,P,and K contents of mycorrhizal fungi were studied;?3?The seedlings of Picea schrenkiana were inoculated by single-inoculation method.According to the threshold of aluminum stress of Mycorrhizal fungi,the Al³⁺concentration(high aluminum concentration was1.0 mmol·L^-1)was determined.The high-aluminum concentration inoculated with mycorrhizal fungi,the biomass and specific root and other physiological and ecological indicators of spruce seedlings and the stress resistance indicators such as malondialdehyde and soluble sugar were analyzed by multiple comparison methods to determine aluminum stress from the perspective of mycorrhizal fungi.The main findings are as follows:?1?After the high concentration of Aluminum(1.0 mmol·L^-1)treatment,only Tr colony diameter increased by 11.4%compared to the control,Me and Ph were not significantly affected by Aluminum,colony diameter was significantly of Si and Sc lower than the control?P<0.05?;Low pH value did not significantly affect Tr and Me colony diameter,but inhibited Ph,Si and Sc growth significantly compared to that of the control?P<0.05?;Aluminum resistant property of five strains exhibited differences at high Aluminum and low pH.The diameter of Tr colony reached the maximum,Ph and Me colony increased by 14.1%and 2.3%,respectively,while Si and Sc decreased by 5.0%and 5.3%,respectively.?2?Except for Si,other strains were inhibited by active Aluminum concentration to varying degrees,Si biomass was positively correlated with active Aluminum concentration,and low content of Aluminum was increased by 238%compared with control?P<0.05?;the biomass of Me,Tr,Ph and Sc decreased,among which,Ph and Sc decreased by 38.1%and 72.5%,respectively.?P<0.05??3?Except for Ph,the H⁺secretion of Si,Me,Tr and Sc was lower than CK at a high content of Aluminum,and there was a significant difference in Si?P<0.05?.Only Me detected oxalic acid,and the amount of oxalic acid secretion was 1.12 times higher than CK.?4?The content of P and K in Si,Sc was positively correlated with the concentration of active aluminium,significantly higher than that in control?P<0.05?,but there was no significant difference in Sc.The content of N in Me and Ph was negatively correlated with the concentration of active aluminium,which was significantly lower than that in control?P<0.05?.The content of P and K in Me reached the peak value at low aluminium and high aluminium respectively,while the content of N,P and K in Tr,Ph was low.When Aluminum reaches its peak value,it is inhibited when Aluminum is high.?5?In summary,under the condition of high Aluminum concentration,five mycorrhizal fungi showed different degrees of promoting and inhibiting effects on spruce seedlings.the whole plant biomass showed that the biomass of the whole plant was Si>Ph>Tr>Me>Sc.The fresh weight of Si was significantly higher?P<0.05?than that of Sc strain,which was 90.1%higher than that of Sc,while other strains did not change significantly.?6?The five mycorrhizal fungi have different effects on the growth of spruce seedlings than root length.The specific root length of Tr is the largest,and the specific root length of Sc is the lowest,significantly?P<0.05?higher than Sc,and 11.4%higher than Sc.?7?Me is the highest soluble sugar content of the five mycorrhizal fungi.The malondialdehyde content of Si is the highest among the five mycorrhizal fungi,and the malondialdehyde content of Tr is the lowest,significantly?P<0.05?higher than Tr,and increased by 253%compared with Tr.The other three mycorrhizal fungi have similar malondialdehyde content.The malondialdehyde content of the five mycorrhizal fungi was Si>Me>Ph>Sc>Tr.