Screening And Application Effect Analysis Of Endophytes Of Dissolved Phosphorus And Nitrogen Fixation In Broom Corn Millet

The endophytic strains with the ability of phosphorus-soluble,nitrogen-fixing were isolated and screened from the seeds of different broom corn millet varieties from Ningxia and Gansu,and inoculated in broom corn millet to evaluate the effects of phosphorus dissolution,nitrogen fixation and growth promotion.At the same time,pot experiments were conducted to determine its effects on seedling growth,photosynthesis and phosphorus-nitrogen absorption,and field experiments were further conducted to verify the influence of strains on growth,yield and water efficiency of broom corn millet under natural conditions.The main results are as follows:?1?Among the endophytic fungal strains isolated from broom corn millet seeds,5strains had the ability to dissolve phosphorus,2 strains were from Gansu LM1?Talaromyces sp.?,LM2?Talaromyces sp.?,and 3 strains were from Ningxia GM1?Talaromyces sp.?,GM2?Penicillium sp.?,GM3?Penicillium chrysogenum?.The phosphorous dissolving capacity was determined by phosphorous ring and molybdenum-antimony colorimetric method,the ratio of the diameter of solubilizing phosphorus circle to the diameter of colony D/d of strain GM1 and GM3 was the largest,reaching 1.59 and 1.47;the content of soluble phosphorus in the liquid medium of the same composition was 264.75?g/m L and 323.48?g/m L,respectively,and the phosphorus dissolution rate reatched 5.26%and 6.43%,respectively,which were significantly higher than other strains?p<0.05?;the p H value was 2.88 and 3.63,respectively,which were significantly lower than other strains?p<0.05?,the phosphorus dissolution rate of the 5 fungis were negatively correlated with the p H value?p<0.01?.In the pot experiment,when the phosphorus consumption was reduced by 75%and 50%and inoculated with phosphorus-soluble fungi GM3,the SPAD value?a parameter of chlorophyll relative content?of broom corn millet was 20.63 and 21.46,respectively,net photosynthetic rate reached 23.2 and 25.87?mol m^-2s^-1,the total phosphorus content of the plant was 10.09and 12.39 mg/pot,respectively,which were significantly higher than the control?CK??p<0.05?.The results showed that inoculation of GM3 had obvious pro-growth effect on broom corn millet and could effectively reduce phosphorus by 40 mg/kg.GM3?Penicillium chrysogenum?was the target strain obtained in this experiment and showed a good effect of promoting the growth and dissolved phosphorus.?2?Nitrogen-fixing bacterias were screened by nitrogen-free medium and amplified nif H gene?nitrogenase gene?.The study showed that after the reaction of PCR amplification of nif H gene was completed,electrophoresis was conducted on 1%agarose gel,and there were 3 strains that could produce obvious bands under the ultraviolet gel imager.Among them,2 strains were from Ningxia,BGM1?Delftia sp.?,BGM2?Paenibacillus sp.?,1 strain was from Gansu BLM3?Enterobacter sp.?.In the pot experiment,when nitrogen deficiency and nitrogen consumption was reduced by 75%and 50%and inoculated with nitrogen fixation bacteria BGM2,the SPAD value of broom corn millet was 22.82,24.73,25.77,respectively,and the net photosynthetic rate was 15.59,17.89,22.94?mol m^-2s^-1,respectively,the total nitrogen content of plant was 0.10,0.13 and 0.14 g/pot,respectively,which were significantly higher than the control?CK??p<0.05?.The results showed that inoculation of BGM2 had obvious pro-growth effect on broom corn millet and could effectively reduce nitrogen by 78.7 mg/kg.BGM2?Paenibacillus illinoisensis.?was the target strain obtained in this experiment and showed a good effect of promoting the growth and nitrogen-fixing.?3?The effects of phosphorus-soluble and nitrogen-fixing strains on the yield of broom corn millet were further verified by field experiments.The results showed that the yield of broom corn millet under the treatment of strain GM3 and BGM2 reached 0.36 kg/m²and0.39 kg/m²,respectively,which was significantly higher than that of the control?CK??p<0.05?.GM3 could significantly increase the main panicle weight and the main panicle grain weight of broom corn millet,which was 119.35%and 108.33%higher than the control?p<0.05?.Under the treatment of strain BGM2,the main panicle weight and the main panicle grain weight of broom corn millet increased by 71.05%and 82.14%compared with the control?p<0.05?.Meanwhile,strains GM3 and BGM2 could significantly improve the water use efficiency of broom corn millet,reached 0.78 kg/mm and 0.76 kg/mm,respectively?p<0.05?.The results showed that the inoculation of GM3?Penicillium chrysogenum?and BGM2?Paenibacillus illinoisensis.?in field could effectively increase the yield and improve the water use efficiency of broom corn millet.