| To investigate the effect of rhizobia treatment on the growth of Alfalfa and its seed yield,Xinmu No.1(Medicago varia cv.Xinmu No.1)was selected as the main object in this research and was treated by four kinds of methods,including soybean rhizobia inoculation(DD),alfalfa rhizobia inoculation(MX),drug sterilization(MJ)and non-sterilization(CK).Then the field plot experiments were used to explore the effect of four treatments on the physical and chemical properties of soil,characteristics of rhizobia,growth and development of alfalfa,and seed yield.As a result,the optimal rhizobia specie affecting the growth and seed production of alfalfa was determined.The main aim of this research is to provide a theoretical basis and a technical support for improving the alfalfa yield and promoting the alfalfa industry development in the northwest arid area.The results are shown as follows:(1)Effect of inoculating different rhizobia on the physical and chemical properties of soil.After inoculating Rhizobium,the contents of organic matter,alkali-hydrolyzable nitrogen and available phosphorus in soil increased at first and then decreased,and the content of alkali-hydrolyzable nitrogen increased by 17.1%at pod-setting stage,the effect of inoculating alfalfa Rhizobium was better than that of inoculating soybean Rhizobium,and the bactericidal treatment had certain inhibition on soil physical and chemical properties.(2)Effects of inoculating different rhizobia on the growth and photosynthetic characteristics of alfalfa.Compared with CK,the plant height,aboveground biomass and underground biomass increased by38.7%,44.2%and 99.7%respectively.The plant height,aboveground biomass and underground biomass were increased by 34.3%,20.0%and 43.2%respectively.The height,aboveground biomass and underground biomass decreased by 2.0%,32.6%and 1.5%respectively.The SPAD value of alfalfa inoculated with Rhizobium was higher than that of other treatments in the period of strong photosynthesis.Inoculating Rhizobium promoted the photosynthetic and physiological characteristics of alfalfa and promoted the growth of alfalfa.(3)Effect of inoculating different rhizobia on the nutrient content of alfalfa.The contents of nitrogen and phosphorus in each part of Alfalfa inoculated with rhizobia were higher than those in the control and sterilization treatments.With the change of growth period,the nutrient contents in various organs showed a trend of first increasing and then decreasing,and the nutrient contents in Alfalfa inoculated with rhizobia were higher than those in the other three treatments.(4)Effects of inoculating different rhizobia on the characteristics of rhizobia.The weight,number and activity of rhizobia of alfalfa were the best after inoculating with Rhizobium of alfalfa,and there were significant differences between the two treatments,the number,weight and activity of rhizobia increased by 76.05%,224%and 34.57%compared with CK.With the different growth period,there was a trend of increasing at first and then decreasing,and the effect of inoculating alfalfa rhizobia was better than that of soybean rhizobia.(5)Effect of inoculating different rhizobia on seed yield components and seed yield of alfalfa.The number of single branch inflorescences,single inflorescence florets,single inflorescence pods and thousand seed weight reached the maximum after inoculating alfalfa rhizobia,while the number of single branches was the maximum under the inoculation of soybean rhizobia.Meanwhile,the maximum weed yield(525.76 kg/hm~2)was found after inoculating alfalfa rhizobia.Sterilization treatment inhibited the seed yield constituents to some extent,which further reduced the seed yield of alfalfa.In summary,the optimal growth and photosynthetic characteristics,nutrient utilization and seed yield of alfalfa could be found under the inoculation of alfalfa rhizobia.Therefore,this study preliminarily determined that inoculating alfalfa rhizobia could be used to further improve the yield. |
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