Effects Of Arbuscular Mycorrhizal Fungi And Nutrient Interaction On The Drought Resistance Of Leymus Chinensis

Water is an important limiting factor for vegetation productivity in the Northeast china.At present,drought has become one of the most serious natural disasters in the Songnen Plain,seriously threatening the production and ecological security of agriculture and grassland ecosystems.Leymus chinensis,a dominant species of azonal vegetation in L.chinensis grassland of the Songnen Plain,showed strong ecological adaptability.Previous experiments have found that the root system of L.chinensis can form a symbiotic relationship with the arbuscular mycorrhizal fungi(AM fungi),but few studies explored the process and mechanism of whether AM fungi can improve the adaptation of L.chinensis to drought stress.Clarifying the mechanism of AM fungi to improve plant drought resistance can not only effectively improve the drought resistance of plants,but also provide an effective bioremediation pathway for the reconstruction of degraded grassland.L.chinensis was used as the plant material in this experiment.Two pot experiments were carried out during two growing seasons to investigate whether AM fungi under different nutrition conditions could affect the drought resistance of plants and their recovery ability after drought,and what was the ecological mechanism? Main results and conclusions were obtained as follows:(1)Drought stress significantly inhibited the growth and development of L.chinensis.The biomass,relative plant height growth rate,specific leaf area,and the reproduction potential of L.chinensis were remarkably reduced by drought treatment as well as the water content of shoot and root.Moreover,the biomass allocation was shifted by drought.And the effect of water stress on the belowground biomass was greater than the aboveground biomass.The root structure of L.chinensis was significantly affected by water treatment.Drought stress reduced the root length,surface area and volume of root,rhizome and fibrous root of L.chinensis.(2)Both water and nutrient treatments significantly affected the percentage of AM fungi colonization.Drought stress reduced the percentage of AM fungi colonization of L.chinensis roots and the percentage of was significantly higher under low nutrient conditions than that under high nutrient conditions.The symbiotic relationship between AM fungi and L.chinensis was weakened by the addition of soil nutrient.(3)AM fungi promoted the growth of L.chinensis.Both the Ge and Gm inoculated to soil significantly increased the total biomass and the specific leaf area of L.chinensis,but the effect of AM fungi on the other indicators of L.chinensis(such as aboveground biomass,biomass allocation,the root structure and growth parameter)was not significant.Water stress inhibited the effects of AM fungi on plant performance.(4)Effects of different AM fungi on the root structure of L.chinensis.Compared with the Ge inoculated to soil,the Gm treatment significantly increased the root length,root surface area,fibrous root length,fibrous root surface area and fibrous root volume of L.chinensis.(5)AM fungi can promote the recovery ability of plants after drought.After restoring water,the Ge inoculated to soil could the percentage of AM fungi colonization,root length,root surface area,root volume,fibrous root length,fibrous root surface area and fibrous root volume of L.chinensis could be restored to the normal water treatment state.But the CK and Gm treatment,the percentage of AM fungi colonization,root length,root surface area,root volume,fibrous root length,fibrous root surface area and fibrous root volume of L.chinensis have improved,but still lower than normal water treatment.In summary,AM fungi can improve the drought resistance of plants mainly through two ways: on the one hand,AM fungi can promote plant growth and improve plant drought resistance;On the other hand,it improves its drought resistance and the recovery ability after drought by changing the root structure.In addition,Ge has outstanding effects in improving the ability of plants to recover after drought.The results of this study not only reveal the ecological mechanism of AM fungi to improve the drought resistance of plants,but also provided theoretical basis for formulating reasonable grassland restoration measures.At the same time,it provides certain experimental data for screening drought-tolerant strains or flora.