| Larix gmelini is one of the three main coniferous forest trees in northeast China.Its’ trunk is straight,its’ branches and leaves are delicate,and its’ leaves turn yellow in autumn.It is often used as an ornamental tree in parks and scenic areas.Not only that,its wood is heavy and solid,resistant to decay,so it also has great economic benefits.However,The daxinanling forest region severe natural disasters in recent years,and the soil heterogeneity is serious,As the main component,the hingan larch cannot recover by itself,which is in urgent need of manual solution.Besides,the outbreak of quenching disease in the seedling stage of hingan larch is serious,and the common chemical control produces certain side effects,which requires a new solution.Ectomycorrhizal Fungi(ECMF)can help plants promote the growth and improve the disease resistance.However,soil pathogens inhibit plant growth by infecting plant roots.In this study,using the method of greenhouse potted control experiment,Taking the Larix gmelini as the host plant,Six kinds of ectomycorrhizal fungi were used to investigate the mycorrhizal effect of different mycorrhizal fungi under different soil nutrients.By measuring the infection status,aboveground and underground biomass,root system,leaf system,nutrient element content and functional index,Screening out good strains,and do further research on disease resistance,By measuring the activity of related enzymes in plant leaves and exploring the mechanism of disease resistance,It provides a theoretical basis for future application of larch seedlings in landscape and forest restoration.in the future.The main research results obtained in this paper are as follows:(1)Without fertilization,6 types of mycorrhizal fungi are good symbiosis with Larix gmelini,they promote the growth of the plant root,leaf and the absorption of nutrients,increase the plant biomass and root weight density,Reduced specific root length and root-cap ratio.which exert the most significant effect on Gr,total biomass increased by 104%,the plant height increased by27.56%,leaf area increased by 44.19%,the root area increased by 55.26%,root length increased by 59.12%,total nitrogen content increased by 20%,total phosphorus content increased by 16.42%,and total potassium content increased by 21.73%.(2)Mycorrhizal effect is influenced by nutrient content,The symbiotic effect between plants and mycorrhizal fungi was better under nutrient stress(without fertilization).When nutrients were sufficient(after fertilization),the dependence of plants on exogenous mycorrhizal fungi decreased.except Gr and Be,all the other strains showed negative effects.Among them,Gr-F compared with CK-F,the total biomass increased by 20.66%,plant height increased by 18.49%,root length increased by 15.90%,root area increased by 17.79%,total phosphorus content increased by 28.40%and total potassium content increased by 23.73%.Be-F compared with CK-F,the total biomass increased by34.87%,plant height increased by 22.40%,root length increased by 1.72%,root area increased by 13.74%,total nitrogen increased by 4.32%,total phosphorus content increased by 38.88%and total potassium content increased by50.67%.(3)Ectomycorrhizal fungi can enhance disease resistance by symbiosis with Larix gmelini Compared with CK,the plants treated with mycorrhizal fungi reduced the content of MDA and increased the content of SOD,POD,PPO and tannin.The combined treatment(Gr+Be)showed higher advantages than the control and single strain treatment,and this advantage existed under the conditions of fertilization treatment and pathogen treatment.(4)Nutrient co-existence with exogenous mycorrhizal fungi is more conducive to reducing plant damage Inoculation of pathogenic bacteria can reduce the biomass of larch seedlings in xing ’an,and the increase of nutrients after the application of pathogenic bacteria is conducive to the increase of the biomass of mycorrhizal plants seedlings.In particular,the biomass and nutrients of plants inoculated with Gr reached a significant level before application,with an increase of 119.38%.However,increasing nutrient treatment did not significantly promote the biomass of CK treatment,and even the biomass tended to decrease.According to the enzyme indexes of larch mycorrhizal seedlings,the contents of MDA in mycorrhizal plants were significantly reduced by fertilization under the stress of pathogenic bacteria.It indicates that fertilization can promote the biomass of mycorrhizal seedlings and various growth indicators,thus improving the plant’s disease resistance,reducing the damage status of plants,and thereby reducing the content of related enzymes in plants.It has been proved that the symbiosis of ectomycorrhizal fungi and plants can reduce the inhibition of pathogens and have a stronger effect under the condition of better soil nutrient.In summary,ectomycorrhizal fungi can promote the growth of larch seedlings in xing an,and mycorrhizal effect is affected by soil nutrients.Excellent strains can improve plant disease resistance,and the combinations of strains under different nutrients have the most significant disease resistance。... |
