Study Of Screening High Efficient Rhizobium Of Vicia Villosa Roth & Vicia Sativa And The Law Of Decomposition

Vicia villosa roth and Vicia sativa,common leguminous green manure crops in Sichuan,play important roles in agricultural production due to the symbiotic fixation with rhizobium.Now there are not related research reports about the screening and application of high efficient rhizobium of Vicia villosa roth and Vicia sativa from Sichuan districts.This study screened out to get high efficient rhizobium strains of Vicia villosa roth and Vicia sativa by means of sand culture tieback test of 31 Vicia villosa roth rhizobium and 66 Vicia sativa rhizobium from Sichuan districts,growth promoting stress resistance property determination test of green manure rhizobium,field verification test of 11 re-screening strains and phylogeny research of rhizobium with field experiment.To discuss the differences of nutrience release tendency during decomposition of Vicia villosa roth and Vicia sativa conducted by inoculated and not inoculated rhizobia,this study still adopted nylon bags methods to carry out green manure decomposing rates experiment.The main research results are as below:(1)24 Vicia villosa roth rhizobia and 43 Vicia sativa rhizobia,separated from root nodules of these Vicia villosa roth and Vicia sativa collected from 15 cities and counties,27 villages and towns of Sichuan,are all fast-growing rhizobia.(2)In sand culture experiment preliminary screening,the strains tested through 67 rhizobiums all gotten by vaccination separation both for Vicia villosa roth and Vicia sativa all can make two kinds of green manures generate nodulation.Nodule number of Vicia villosa roth is 13.0～81.0 /plant,the each plant dry weight 83.3～231.1 mg,the dry weight of 52 plants conducted by inoculated rhizobiums are more than contrast,and the dry weight of 12 plants conducted by inoculated rhizobiums appeared significant increase(P<0.05).Nodule number of Vicia sativa is 6.3～45.7/plant,the each plant dry weight 69.8～228.7 mg,the dry weight of31 plants conducted by inoculated rhizobiums are more than contrast,and the dry weight of11 plants conducted by inoculated rhizobiums appeared significant increase(P<0.05).(3)The generative effect research on 92 plants rhizobiums shows that all can secrete IAA but there existed great differences among plants secretion volume and IAA volume is0.17～23.75 mg/L,and 13 plants rhizobiums(13/92)produced soluble phosphorus circle on organic phosphorus plate.When conducted by phosphate solubilization quantitative analysis,these 12 plants(12/92)all can partly dissolve organophosphate with capacity of 1.30～67.26mg/L.Moreover,57 plants rhizobiums(57/92)can dissolve K with a capacity of rhizobiums.The resistance research on 92 plants rhizobiums reveals all can grow on p H4.0～11.0 YMA medium but will affect colony growth under peracid or over alkalinity conditions,on0.2%～0.5% Na Cl YMA medium,and 32 plants rhizobiums(32/92)can grow on 0.2%～4%Na Cl YMA medium.(4)After 11 rhizobiums screened out by sand culture tieback test were carried out Field effect verification,the results show that inoculated rhizobiums can promote increasing of total biomass,root nodule number of Vicia villosa roth and Vicia sativa.The total biomass of Vicia sativa by comparision of conducting by inoculated and not inoculated rhizobiums are increased by 43.8%～86.1%,and increased by 0.7%～32.5% same as Vicia villosa roth.The research indicated the best strains in yield increase are VS5-1 for Vicia sativa,significant increase in production.The best strains in yield increase are V14-2 for Vicia villosa roth,no significant increase in production.(5)Through the phylogeny researches on high efficient rhizobiums screened by field experiment including 16 S r DNA,housekeeping gene(rec A、gln II and atp D)and symbiont gene(nod C、nif H),it found out that all 11 rhizobiums belong to Rhizobium category and are confirmed to mainly be parts of R.anhuiense、R.fabae and R.sophorae by joint contributions of housekeeping gene.The symbiont gene generated horizontal transfer phenomenon compared with housekeeping gene.(6)Using nylon bags method studied the influences on decomposition regularity and nutrience release tendency of Vicia villosa roth and Vicia sativa after turning conducted by inoculated rhizobiums under field conditions and not inoculated rhizobiums.The results indicated such tendencies,faster decomposition at earlier stage and stable decomposition at later period,and obsolete difference between inoculated and not inoculated rhizobiums.For Vicia villosa roth,its N,P,K elements release tendency are basically consistent and nutrience release rate appeared K>N>P.Meantime,for Vicia sativa,its K,N release tendency are faster at earlier period and stable at later stage.And P also basically maintain one stable release.The relationship among decomposition tendency,nutrience release rate(y)and time(t)can be preferably fitted by equation.Cumulative release rate of green manure cellulose appeared such growing trend of increasing by time and from fast to slow.Cellulose decomposition rate53.31%～70.93%.But cumulative release rate of hemicelluloses and lignin showed irregular,the relationship can’t be described between release rate(y)and time(t)using equation.The decomposition rate of hemicellulose and lignin is 74.57%～86.56% and 53.83%～73.36%.And the release tendencies basically keep consistent without any significant difference among cellulose,hemicelluloses,and lignin of inoculated and not inoculated rhizobiums.