| Hedysarum scoparium was mainly distributed in the desert area of Northwest China,which was constructive or dominant species in the desert environment.Due to the strong root system and resistance,it was an ideal plant for windbreak and sand fixation.Arbuscular mycorrhiza fungi,which was a fungi widely distributed in the soil of natural ecosystems,can form reciprocal symbiosis with most vascular plants.Thus,AM fungi can promote plants to absorb nutrients and growth,and enhance the resistance to drought of the plant.Therefore,it was significant to study the symbiotic characteristics and ecologo-geographical distribution of AM fungi in the rhizospheres of H.scoparium.This study was carried out in 2015,2016 and July 2017,correcting the soil and root samples of Ordos,Dengkou,Wuhai,Alashan in Inner Mongolia;Shapotou in Ningxia;Mingqin and Anxi in Gansu.These sample sites distribute from the east to the west along H.scoparium natural distribution area in northwestern desert,China.The objectives of this study were to describe the symbiotic characteristics,spatio-temporal distribution of AM fungi and their correlation with environmental factors,and analysis the response of AM fungi in different habitats to eco-geographical environment.The purposes of this study were to elucidate the mechanism of H.scoparium adapted to extreme desert environment,to reveal the ecologo-geographical distribution of AM fungi,and to provide a basis for the use of AM fungi to restore vegetation and improve desertification.The main results as follows:1.The roots of H.scoparium and AM fungi can form a typical intermediate type arbuscular mycorrhizas.The hyphae,vesicles and arbuscule were the main structures of AM fungi.The total colonization was 64.07% and spores density was 84/20 g.H.scoparium can form well symbionts with AM fungi.2.Along the northwest desert zone from the east to the west along with the drought,the twining degree of the hyphae of AM fungi decreases and branches increase;the diameter of the vesicle decreases and the shape changes from the circle to the fusiformis;the form of arbuscular mycorrhiza changes from the condition that P-type take a high proportion to the condition that A-type takes a high proportion.3.The distribution of AM fungi was significantly spatio-temporal heterogeneity.Total colonization in 2015 was obviously lower than that in 2016 and 2017,it decreased gradually from the east to the West in the geographical distribution.Spores density in 2015 was obviously higher than that in 2016 and 2017,it has significant differences among different sample sites.4.The arbuscular colonization rate of AM fungal is positively correlated with hyphae,vesicles,total colonization rate and colonization intensity of DSE.Colonization intensity of AM fungi was positively correlated with microsclerotia of DSE.5.The temporal and spatial distribution of AM fungi is closely related to soil factors.Total colonization of AM fungi was positively correlated with soil moisture and organic matter,and negatively correlated with soil temperature.Spores density was positively correlated with soil moisture and phosphatase,and negatively correlated with pH.6.The geographical distribution of AM fungi was closely related to the geographical and climatic factors.Hyphae,vesicles,total colonization and colonization intensity of AM fungi were positively correlated with longitude and negatively correlated with annual evaporation.Arbuscule and spores density were positively correlated with annual rainfall and negatively correlated with annual mean temperature.7.Principal component analysis showed that soil temperature,moisture,phosphatase and pH were the main influence soil factors,which can reflect the nutritional status of the desert soil in Northwest China.The longitude,elevation,annual rainfall and annual evaporation were main influence geographic and climatic factors,which can reflect the geographical and climate features of the desert in Northwest China. |
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