| Arbuscular mycorrhizae(AM)fungi is the most widely distributed soil microorganism which can symbiosis and form AMF-plant symbiosis with most higher plants.AM fungi help plants gain nutrients,promote plant growth and development,improve plant resistance and reduce the salt and alkali damage to plants by changing the soil structure and other functions.AM fungi and host plants are mutually beneficial,and AM fungi maintain the stability of the host plant rhizosphere environment under adverse environment.Iris lactea is a grass flower that has both salt tolerance and very high ornamental quality.Studies have shown that there are symbiosis of AM fungi in the rhizosphere,but the distribution and diversity of AM fungi in their rhizosphere have not been reported.In this study,Iris lactea was selected as the research object in Songnen-Saline grassland.The root system and rhizosphere soil of Iris lactea were collected to investigate the diversity of AM fungi and the characteristics of mycorrhizal infection in July 2016.Morphological identification methods were used to identify the diversity and dominant species of AM fungi in the rhizosphere and further validate the identified superior AM fungal strains by molecular biological identification.basis on this study,petunia was the host plant,and the dominant bacterium was inoculated by single inoculation and mixed inoculation.The effects of AM fungi on the physiological metabolism,rhizosphere enzyme activities,water status and chlorophyll content in petunia were determined to screen the dominant AM fungus strains of Iris lactea and provide the theoretical basis on the repairment of saline-alkali grassland.The results are as follows:1.The results of observation and calculation of 10 different mycorrhizal fungi showed that AM fungi invaded the horseshoe crab and formed the mycorrhizal structure of Arum.In general,the infection rate of roots increased firstly and then decreased with the increase of pH.The infection rate and infection intensity reached the maximum at pH 8.2,which were 73.33%and 28%respectively.The maximum of vesicles and branches abundance were 8.79%and 4.07%at pH 8.2 and pH 8.17,respectively.AM fungi produce a large number of mycelium and vesicular structure in the root.2.AM fungi were identified with morphologically from 10 samples,and 37 species of 12 genera of AM fungi were isolated and identified.Glomus and Funneliformis accounted for 23.79%and 22.57%of the total,respectively,which were the dominant genus for isolation and identification.Funneliformis mosseae and RhizopHagus intraradices were isolated in various plots,with important values of 58.62 and 51.19,respectively,which were the dominant species isolated and identified.The method of molecular biology identification was used to further validate the dominant species,and the serial numbers received from NCBI were KY245948 and KY967599,respectively.The results were completely consistent with the morphological identification.3.In order to verify the effect of the superior AM fungi of Iris lactea on host plant resistance,medium salt-tolerant plant Petunia hybrida was used as test material to inoculate the the superior AM fungi of Iris lactea rhizosphere to verify its functionality.The superior AM fungi were inocalated to Petunia hybrida 65d,found that AM fungi were infectied.under 0.6%salt concerntration different level,mycorrhizal dependency reached grade ?,with high mycorrhizal dependence.4.Compared with the non-inoculated Petunia hybrida,inoculation of AM fungi(Funneliformis mosseae and RhizopHagus intraradices)can improve plant enzyme activity,soluble protein content,chlorophyll content and tissue water content of petunia,and reduced the amount of malondialdehyde,proline,water saturation loss and relative conductivity,which functioned obviously with mixed inoculation.The results showed that inoculation of AM fungi could increase salt tolerance of Petunia hybrida,reduce the toxic effects of salt stress on Petunia hybrida. |
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