Effect Of Different Strains Combination On Growth And Physiology Of Acacia Melanoxylon

The phenotype characteristics of morphologyl,physiologyl and biochemical characteristics of Rhizobium,phosphorus-solubilizing bacteria,Silicate bacteria,had beens idenfified.And the ability of nitrogen fixation,phosphorus-disssolving, Potassium-disssolving among these strains had been mensurated.Gathering the ectomycorrhizal fungi of masson pine for enlarging culture.And taking fast growing Acacia melanoxylon species as experimental material,in the condition of water stress,analysing the growth effect of Acacia melanoxylon seedling for inoculated with strains combination which founded by Rhizobium and ectomycorrhizal fungi, phosphorus-solubilizing bacteria and Silicate Bacteria.After the treatment of low temperature,the physiologyl and biochemical characteristics of Acacia melanoxylon seedling had been studied for inoculating strains combination.The results show as follows:1.The tested strains of Rhizobium are gram-negative bacteria,without secreting the amylase and protein hydrolase,and without producing 3-Keto lactose.Only N₂ strain could use citrate among the tested strains,the majority of strains both could use monosaccharide and polysaccharide.Rhizobium strains could grow in the test under the conditions of pH 5-9,the optimum pH value for the growth was 7-8;different strains of Rhizobium was different in nitrogenase activity,to N₂ strain it recerved the highest value at 0.48 umol/g·l.2.The great majority of phosphorus-solubilizing bacteria screened for the test are Bacillus megaterium and Bacillus cereus,one of the strains was Bacillus badius.All the strain secreting the amylase and protein hydrolase,in addition to P₄ strain,the other strains could hydrolysis sugar and produced acid substance.they appear positive in V-P test.In the early stage of inoculating Phosphorus bacteria,the pH value of the fermented broth were significantly decreased,and stable after 3 d. Through the phosphate-dissolving test,the content of soluble phosphorus in the fermented broth which inoculated P₃ strain was the highest at 50.27 ug/mL.3.Silicate bacterias screened for the test are gram-negative bacteria,it grew well in the Nitrogen free medium,formed a full,flexible,thick glass bead-like mycelial colonies.The tested bacteria could secret the amylase and protein hydrolase,also could use citrate except S₃ strains,all strains appear negative in V-P reaction,and make use of glucose,but S₃,S₅ strain could not use mannitol.At the same time, Silicate bacteria had obvious inhibition effect on mildew,with the treatment of inoculating S₃ strains,the rate of mildewy seed decreased to 25 percent,a reduction of nearly 150 percent compared with the contrast.Different silicate bacteria had great difference in Potassium-disssolving ability,the best inoculation effect was the S₅ strain,in it's fermented broth the soluble potassium content was as high as 65.92 ug/ mL.4.By the test outdoor,different combinations of microbial strains had promotion on Acacia melanoxylon seedlings,raised nodulation rate,height and biomass.In which,the effect of combination strains 8 was particularly evident,compared with the contrast,the rate of nodulation increased 400 percent,117.99 percent in the seedling height,106 percent in biomass.5.The study results shows,the membrane permeability,chlorophyll content,SOD and POD content,soluble sugar and proline content,became differtent under water stress and the treatment of different combination.Constrasting to watering,we founded that the relative conductibility of leaves increased,such as 31.32%to 58.22%after the treatment of strains combination 4;the content of chlorophyll descend,such as 1.326 mg/g to 0.762 mg/g after the treatment of strains combination 7;the activity of SOD,POD had been enhance,such as 40.267 U/g·min·FW to 73.397 U/g·min·FW to SOD after the treatment of strains combination 2;and 12.523 U/g·min·FW to 16.737U/g·min·FW to POD after the treatment of strains combination 4.The content of soluble sugar and proline had been enhance,such as 110.42 mg/g·FW to 173.30 mg /g·FW to soluble sugar after the treatment of strains combination 1;and 9.867mg /g·FW to 21.52 mg /g·FW to proline after the treatment of strains combination 9.Contrasting no inoculation,in the different water stress condition,the physiologyl and biochemical characteristics of Acacia melanoxylon seedling represent differently.The relative conductibility decended down to 27.21%after the treatment of strains combination 1 when providing plentiful water;as 40.32%to strains combination 7 In drought conditions;strains combination 8 was the highest in chlorophyll content in the two condition of above;as 0.823 mg/g in watering condition and1.341 mg/g in drought conditions;SOD content is hight at 73.897 U/g·min·FW in watering condition and 93.273 U/g·min·FW in drought conditions after the treatment of strains combination 8.As POD content increased to 12.523U/g·min·FW in watering condition and 16.737U/g·min·FW in drought conditions after the treatment of strains combination 4;soluble sugar content increased to 183.533 mg/g·FW,and proline to 21.52 mg/g·FW in drought conditions after the treatment of strains combination 7 and 8.