Colonization Of An Inoculated Rhizobium Strain And Its Effects On The Nodulation,Nitrogen Fixation And Production Of Alfalfa Under Subsurface Drip Irrigation

In this study,the basis of preliminary work has been screened an Sinorhizobium meliloti strain XGL026,which material was transferred green-fluorescent protein gene.By the experiment of alfalfa field plot under subsurface drip irrigation,measured the effects of different inoculation treatments on the colonization,nodulation and nitrogen fixation of rhizobia and alfalfa yield,quality,rhizosphere microenvir-onment.To clear the key technical parameters of rhizobium application and magnetized water treatment,in order to give full play to the nitrogen fixation efficiency of rhizobia,establish alfalfa high-yield,high-quality,efficient production system,improve the grassland production ability,provide scientific basis and technical support for the efficient use of water resources in arid areas.The main results were as follows:The colonization and nodulation characteristics of rhizobia were detected by fluorescence detection.In two-year-old alfalfa plants,the first year inoculation treatments still maintain a high colonization density and competitive nodulation ability.Which the treatment of I?B+D2+N2?+II?N2?was higher than other treatments.One-year-old alfalfa plant without rhizobia inoculation,complement drip irrigation rhizobia can obtain a higher colonization density and competitive nodulation ability,II?D2?was higher treatments.The treatment of I?B+D2+N2?+II?N2?and I?B+D2?had a high colonization density and competitive nodulation ability in the 1st cutting;The treatment of II?D2?had high colonization density and competitive nodulation ability in the 2nd and 3rd cutting.rhizobium inoculate could increase the nodule distribution on the lateral root.One-year-old alfalfa plants inoculated with rhizobium,the inoculation of rhizobia has not been detected in four-year-old.By complement drip irrigation rhizobia 1 or 2 times can significantly increase the colonization of rhizobia,improve nodulation and nodule occupancy,has a significant complement inoculation effect.The effect of complement drip irrigation rhizobia twice?IB+IVD2?treatment was significantly better than the effect of complement drip irrigation rhizobia once?IB+IVD1?.The nodule absolutely concentrated in the lateral root.The nitrogen fixation efficiency of alfalfa was measured by ¹⁵N natural abundance method.Two-year-old alfalfa,compared with CK,II?N1?,inoculation treatment can significantly improve the proportion of N fixed and increase the amount of N fixation of alfalfa during the whole growing season.And in the treatme-nt I?B+D2+N2?+II?N2?,I?B+D2?,the average proportion of N fixed and the total nitrogen fixation rate was the highest in three cutting of alfalfa.1-year-old alfalfa plant without rhizobia inoculation,complement drip irrigation rhizobia in second year can effectively improve the N fixation,II?D2?had most prominent in the2nd and 3rd cutting,significantly higher than I?B+D2+N2?+II?N2?treatment.Four-year-old alfalfa,the proportion and the amount of nitrogen fixation of alfalfa treated with IB+IVD1,IB+IVD2 were higher than IB,which IB+IVD2 had most prominent.Two-year-old alfalfa,compared with CK and II?N1?,rhizobium inoculation treatment could increase forage yield,increase the content of crude protein content in alfalfa,reduce the content of NDF and ADF,and improve the quality of alfalfa.I?B+D2+N2?+II?N2?,I?B+D2?treatments,the total yield and average crude proteion contant was the highest in three cutting of alfalfa.1-year-old alfalfa plant without rhizobia inoculation,complement drip irrigation rhizobia in second year could increase forage yield and improve the quality of alfalfa.II?D2?had most prominent in the 2nd and 3rd cutting,which was higher than I?B+D2+N2?+II?N2?treatment.Correlation analysis showed,under different inoculation treatments proportion of N yield and the hay yield CP content was positively correlated.The alfalfa planting 4 years,compared with IB treatment,IB+IVD1,IB+IVD2 treatment has significant effect of increasing the forage yield and alfalfa quality,and IB+IVD2 were more significant.The results showed that the magnetized water treated at 4 000 Gs had significant effect on the growth and nodulation of S.meliloti,Application of T2 magnetized water in alfalfa production.It was found that the amount of colonization of rhizobium in rhizosphere soil of II?D1+T?was significantly higher than II?D1?.Compared with the control,inoculation treatment could significantly increase nodule numbers,rate of tumor,the N fixation effect and forage yield,II?D1+T?was the highest.The result showed,Inoculation can effectively promote the growth of alfalfa roots,increase the amount of alfalfa nodulation and improve soil fertility.Nodules in the inoculation treatment were concentrated in the 0³0 cm depth and near to the emitter of drip irrigation tapes,the amount of nodulation of II?D2?,I?B+D2+N2?+II?N2?was higher than other treatment.Correlation analysis showed that,there was a positive correlation between rhizosphere microenvironment and alfalfa nodulation and nitrogen fixation efficiency.The total root length,total surface area and root nodule number,nitrogen fixation rate and nitrogen fixation rate of alfalfa were significantly positively correlated.