Screening Of Rhizobium Strains Matched With Medicago Varia Martin.cv.caoyuan No.3 In Three Pilot Planting Areas

In the process of high-yield cultivation of alfalfa,the pre-sowing rhizobia inoculation can effectively increase the forage yield.Besides,selecting an effective strain that matched with each alfalfa was an important part of increasing production.In the actual production,the best matching strains are mainly considered in two aspects: the host plant and the soil environment of the planting area.Usually the differences in indigenous rhizobia,soil nutrients,and host matched will result in poor inoculation.Therefore,suitable rhizobia were screened for the main cultivated areas of M.varia Martin.cv.Caoyuan No.3,and rhizobia matching and screening experiments were conducted on the three planting areas in western Inner Mongolia.The Rhizobium spp.in the ethnically interconnected races(Medicago and Medicago officinalis spp.)was collected from their planting areas and identified by 16 SrDNA classification.The greenhouse preliminary screening and field rescreening were performed.Biomass,nitrogenase activity,crude protein,chlorophyll,and changes in soil physicochemical properties were analyzed to screen root nodule strains with significant yield increase effect on the M.varia Martin.cv.Caoyuan No.3 hybrid,which provided a basis for high-yield cultivation of M.varia Martin.cv.Caoyuan No.3 in these areas.The experimental results were as following:1.The root rhizobia of 9 forage materials in the ethnic group were collected from Shaerqin,Hailiutu,Hohhot,and Guannianfang,and 12 strains were isolated and purified.The strains were identified by 16 SrDNA and belonged two genus that was Rhizobium and and Sinorhizobium for 4 species.2.After analysis of growth indexes,the strain SJN performed the most excellent screening through laboratory tests,followed by HK,HH,and H7;the field tests were conducted in 3 areas of Shaerqin,Hailiutu,Guannianfang,best mached with M.varia Martin.cv.Caoyuan No.3 was SJN,XT,HBH;3.The comprehensive nitrogen-fixing ability of indigenous rhizobia strains(SJN,XT,HBH)had best performance thanthe commercial strain DZ;Nitrogenase activity was not equal to nodulation ability;Different superior strains showed different performances in differentplanting environments indicated that it was very necessary to select the best matching strains for different planting environments and different host plants;4.The inoculation of rhizobia in alfalfa could significantly increase the content of available N,P and K in soil,but had no significant effect on the content of total N and total K.