Isolation Of Culturable Microorganisms From The Rhizosphere Of Allium Mongolicum Regel And Screening Of PGPR Strains

Allium mongolicum Regel is a kind of Allium plant of Alliaceae with high application value,which has the characteristics of drought resistance,cold tolerance,disease resistance,good adaptability and easy to cultivation.Plant growth-promoting rhizobacteria(PGPR)can stimulate plant growth,promote plant rhizoremediation and enhance plant resistance,and can produce antagonistic substances against pathogens and microbes.In order to explore the differences in rhizosphere microorganisms of Allium mongolicumRegel and to screen out excellent rhizosphere-promoting bacteria,this study used Allium mongolicumRegel from three regions in Inner Mongolia as the research object,to isolate the rhizosphere microorganisms of Allium mongolicumRegel by plate separation method,and to screen out the excellent strains with various growth promoting effects by selective medium.The strains were identified according to the morphological characteristics and DNA sequence analysis,and the effects of the excellent strains on the seed germination of Allium mongolicumRegel was examined.The main results are as follows:1.The pH values of rhizosphere soil in three regions are between 6.49 and 7.93,from high to low,respectively,Wuhai,Ordos,Xilinhot.The content of nutrients(ammonium,available phosphorus,available potassium,total nitrogen and total carbon)from high to low were Xilinhot,Ordos and Wuhai,and the difference was significant(p<0.05).The enzyme activities(phosphatase,urease)from high to low were Xilinhot,Ordos and Wuhai,and the difference was significant(p<0.05).2.In the three regions,the number of cultivatable microorganisms in the rhizosphere of Allium mongolicumRegel from high to low were Xilinhot,Ordos and Wuhai.The number of cultivable microorganisms in different regions from high to low were bacteria,actinomycetes and fungi.In the three regions,the number of culturable microbial species from high to low were Xilinhot,Ordos,and Wuhai.The number of microbial morphological species in different regions from high to low were bacteria,fungi,and actinomycetes.3.A total of 3 strains of excellent bacteria with salt-tolerant,alkali-resistant,nitrogen-fixing and phosphorus-promoting properties were screened,and 9 strains of fungi with salt-tolerant,alkali-resistant and phosphorus-promoting properties were also screened.According to morphological and molecular biological identification,the three bacteria strains were all belong to Bacillus,among the 9 strains of fungal,3strains(XF1,XF5,XF6)were belong to Penicillium and 2 strains(EF1,EF5)were belong to Aspergillus,1 strain(XF8)was belong to Eurotiales,and 3 strains(EF2,EF6,WF1)were belong to Talaromyces.4.Compared with the control,the excellent strains EF5 and EF6 all reduced the germination potential of Allium mongolicumRegel seeds,and had no significant effect on the germination rate.EF5 treatment significantly increased the shoot length and fresh weight of the seedlings(p<0.05),and EF6 treatment also significantly increased the shoot length of seedlings(p<0.05),but the difference in fresh weight was not significant.It is concluded that the number and types of microbes in the rhizosphere of Allium mongolicumRegel are different in different habitats,and there are many excellent strains with probiotic potential in the rhizosphere of AlliummongolicumRegel,which might be related to the fact that the secretions in the root system of Allium mongolicumRegel could recruit beneficial microorganisms and inhibit harmful microorganisms at the same time.