| In order to study the influence mechanism on physiological and ecological characteristics of seedlings under different environmental factors,this study took exotic plants Rhus typhina and Acer truncatum seedlings as research objects,and selected nitrogen,water and light in abiotic factors,and arbuscular mycorrhizal fungi(AMF)in biotic factor as an experimen R.typhina and A.truncatum tal condition,then a pot control test was conducted in a greenhouse.A three-factor cross-test was set with two inoculation modes(inoculation and no inoculation),three planting modes(single species of R.typhina,single species of A.truncatum,mixed species of R.typhina and A.truncatum)and three nitrogen addition levels(or two water levels and three light levels),and the physiological and ecological indexes of the two tree species were measured.In order to study the effects of AMF on physiological and ecological characteristics of the seedlings of R.typhina and A.truncatum,the main measurement indexes included:root infection,growth index,biomass accumulation and allocation,leaf functional traits,root morphological characteristics,soil chemical properties and other indicators and the natural logarithm of response ratio was used to evaluate interspecific competitiveness.The main research results are as follows:(1)AMF could form a good symbiotic relationship with R.typhina and A.truncatum.both of which had high mycorrhizal infection rate and arbuscular growth rate.AMF inoculation and nitrogen treatment significantly affected the growth of R.typhina and A.truncatum.Under different nitrogen treatment levels,AMF inoculation increased the plant height,crown width,base diameter and total leaf number of the two species,and the total biomass and root architecture characteristic index of the two species were significantly higher than those without inoculation.Among them,under moderate(N2)and severe(N3)sedimentation conditions,the single species biomass of the torch tree inoculated with AME was the highest,at 13.89 g and 13.65 g,respectively,significantly increasing by 17.12%and 15.09%compared to the condition without nitrogen addition.The increase of nitrogen content promoted the growth of R.typhina.AMF inoculation,nitrogen treatment and planting methods affected leaf morphology and physiological characteristics of R.typhina and A.truncatum.The natural logarithm analysis of the response ratio of the two species showed that AMF inoculation,changes in nitrogen content and planting methods all affected the interspecific competition intensity of the two species.Under the three nitrogen levels,AMF inoculation enhanced the interspecific competition between the two species.(2)The growth of R.typhina and A.truncatum was significantly affected by water.When the soil water content was 25%,the net photosynthetic rate,biomass accumulation and root-shoot ratio of R.typhina decreased,while the root infection,growth,leaf physiological indexes and biomass of A.truncatum were inhibited.Inoculation with AMF did not significantly improve the effects of low soil water content on growth,leaf physiology,leaf morphology,root morphology,biomass accumulation and allocation of A.truncatum.However,inoculation with AMF intensified the inhibition effect of mixed species on biomass accumulation of A.truncatum and enhanced the promotion effect of mixed species on biomass allocation of A.truncatum root under normal water conditions.The natural logarithm analysis of the response ratio of the two plants showed that AMF inoculation,water content change and planting method all affected the interspecific competition intensity of the two plants.The natural logarithm of the response ratio of the two plants was the lowest(-0.55)and the natural logarithm of the response ratio of the two plants was-0.16,when the soil water content was 25%.The AMF inoculation enhanced the interspecific competition between the two types of water content.(3)The growth advantage of R.typhina and A.truncatum was the most obvious under 65%full light,while the growth was slow under 15%full light.Under different light conditions,the net photosynthetic rate,specific leaf area,total root length,biomass and root-shoot ratio of AMF inoculation of R.typhina were higher than those of no inoculation.Under different light conditions,the interspecific relationship was simulated by the mixed species of R.typhina and A.truncatum,the growth of A.truncatum was inhibited regardless of whether AMF was inoculated or not,and the biomass under inoculation was lower than that without inoculation.These results indicated that the AMF inoculated R.typhina under different light conditions intensified the competition inhibition effect on A.truncatum.Compared with no AMF inoculation,AMF inoculation improved the growth inhibition of R.typhina by mixed planting patterns under light conditions. |
PDF Full Text Request