The Distribution And Identification Of Rhizobia And The Effects Of Nitrogen Fertilizer On The Production Performance Of Sweet Clover

The distribution and species of rhizobia from sweet clover were studied in Akesu area.The effect of nitrogen fertilizer on nitrogen fixation ability were determined inpots.The conclusions can guilde for cultivation of sweet clover.The rhizobia were counted by plate dilution method.The rhizobia were isolated form sweet clover soil,and were identified by physiological biochemical method and 16s rDNA gene sequence analysis.It was studied that nitrogen fertilizer effected on quatity and quality of sweet clover.The yield,nutrition and so on were detemined.The nitrogen fixation ability was determined by ¹⁵N isotope dilution method.The nutrition of sweet clover was evaluated by chemical component and in vitro.The results were showed as follows:From the sowing period of sweet clover April to the cutting stage end of September,the rhizobia was distributed the most in 10²0 cm soil layer,followed by 0¹0 cm and 20⁴0 cm.The number of rhizobia was maximum respectively to 6.89 lg cfu·g^-1 in 0²0cm soil in July and 6.46 lg cfu·g^-1 in 20⁴0cm soil in August.The number of rhizobia was accrued in non-symbiotic period than symbiotic by7.33%-10.63%.The correlation was the highest of total salt and the number of rhizobia in 0⁴0 cm soil?average,r=-0.81,p<0.05?.In addition,there was higher correlation between the moisture and the number of rhizobia in 0²0 cm soil?-0.80?r?-0.73,p<0.05?.There was high correlation between the total nitrogen of soil and the number of rhizobia in 20⁴0 cm soil?r=-0.88,p<0.05?.Path coefficients the total salt,organic matter,total nitrogen had the highest correlation with the number of rhizobia,and organic matter was positively correlated?P₅=0.56?,but total nitrogen and total salt were negatively correlated?P₆=-0.5,P₄=-0.64?.The organic matter can promote rhizobia growth,but total nitrogen and total salt can inhibition rhizobia.Two strains rhizobia were islated and identified.One was a fast-growing Sinorhizobium meliloti,and the other was slow-growing Rhizobium huautlense.The plant height,stem diameter and S/L of sweet clover reached the highest in 200 mg·kg^-1 nitrogen fertilizer?p<0.05?,which were 67.30cm,3.51mm and 1.14 respectively.The number of lateral branches of sweet clover was the highest to 21.83?p<0.05?,at 300 mg·kg^-1?soil?nitrogen fertilizer.The tiller numbers and R/T of sweet clover were the highest at 400 mg·kg^-1,1.93 and 2.75,respectively.Nitrogen application could significantly increased the yield of sweet clover.When the nitrogen fertilizer was 200 mg·kg^-1,the yield of sweet clover hay was highest to 1573.94 kg·hm^-2?p<0.05?,and increased 14.05%higher than CK.Compared to CK,the content of Ca was significantly increased when 100³00 mg·kg^-1 nitrogen fertilizer?p<0.05?.Among them,the Ca reached a maximum at 300 mg·kg^-1 of nitrogen fertilizer,and increased 30.77%compared with CK.The content of Atom%¹⁵nitrogen excess in sweet clover increased first and then decreased when 0⁴00 mg·kg^-1 nitrogen fertilizer,and reached an maximum of 0.44%at 200mg·kg^-1.Compared to CK,the content of percent of nitrogen fixation and total nitrogen fixation was significantly reduced when 300⁴00 mg·kg^-1 nitrogen fertilizer?p<0.05?.There was no significant difference in 100 mg·kg^-1 and 200 mg·kg^-1.Thepercent of nitrogen fixation and total nitrogen fixation.Among them,the highest to 17.98%and 386.58 kg·hm^-2at 100 mg·kg^-1,which increased 1.1%and 2.05%higher than CK respectively.The CP was to 12.35% sweet clove hay.The RFV was to 112.3,which belongs to the second grade crude feed.The in vitro gas production of sweet clover reached the highest level at 36 h,which was 107.37mL·g^-1.The in vitro gas production rate of sweet clover was 71.43%higher than that of alfalfa,but it was in vitro gas production was significantly lower than that of alfalfa.sweet clover hay can replace of 87.65%alfalfa hay.In conclusion,It was suggested to apply nitrogen fertilizer in the range of 163.88³27.76 kg·hm^-2.We should improve the organic fertilizer.It can achieve the best results.