Cultivation Condition Optimization Of Rheinella Rheinii NYJ And Saline-alkaline Stress Mitigation In Cucumber By The Strain

Cucumbers are subjected to salt-alkali stress during planting,which will seriously affect the yield and quality of cucumbers.Studies have shown that the strain has a significant role in alleviating salt-alkali stress.In this experiment,the culture conditions of the tested strain NYJ were first optimized,and then prepared as a fungicide The specific research;By using Petri dishes and soil cultivation methods,adding Na₂SO₄,Na₂CO₃and NaCl to simulate the salt-alkali stress environment,the mitigating effect of the tested strain NYJ on cucumber seed and seedling salt-alkali stress was studied.In order to provide a theoretical basis for the role of NYJ strain in alleviating salt-alkali stress.content and results are as follows:（1）In this experiment,the culture temperature,pH and Na₂SO₄concentration of the tested strain NYJ were first optimized,and the optimum temperature of the NYJ strain was37℃,the culture medium pH was 9.14,and the Na₂SO₄concentration was 40 g/L,the number of viable bacteria when NYJ was cultured for 12 hours under this condition was219.05×10⁷cfu/mL.（2）This experiment measured the ability of phosphorus solubilizing and iron-producing carrier within 48h of NYJ strain.The test results showed that with time,the ability of phosphorus solubilizing and iron-producing carrier of NYJ strain showed an upward trend.（3）Compared with the control group,the MDA and H₂O₂content of the shoot roots of Na₂SO₄group increased by 19.71%and 277%;the POD content of the shoot roots decreased by 40.82%,and the soluble protein content increased by 317.2%;Stem length and fresh weight decreased by 73.12%,78.18%,and 55.46%,respectively;compared with the Na₂SO₄group in the NYJ+Na₂SO₄group,the MDA and H₂O₂contents in the seed roots decreased by12.13%and 76.47%,respectively;the POD content in the seed roots increased by 52.35%and the soluble protein content Reduced by 43.59%;the germination rate of cucumber seeds increased significantly,root length,stem length and fresh weight increased by 16.17%,78.57%and 38.42%,respectively.（4）Compared with the control group,the germination rate of cucumber seeds in the Na₂CO₃group was significantly reduced,and the root length,stem length and fresh weight were reduced by 63.84%,48.65%and 57.46%,respectively;compared with the Na₂CO₃group in the NYJ+Na₂CO₃group,the germination rate of cucumber seeds Increase,root length and stem length and fresh weight increased by 56.06%,42.11%and 47.19%.（5）Compared with the control group,the germination rate of cucumber seeds in the NaCl group was significantly reduced,and the root length,stem length and fresh weight were reduced by 69.27%,28.92%and 36.55%,respectively;compared with the NaCl group,the root length of cucumber seeds The stem length and fresh weight increased by 143.1%,16.22%and 44.18%respectively.（6）Compared with the control group,the plant height,leaf area,leaf width,and fresh weight of the aboveground cucumber seedlings in the Na₂SO₄group decreased by 42.71%,67.73%,57.18%,and 51.19%,respectively;compared with the Na₂SO₄group in the NYJ+Na₂SO₄group,cucumbers The seedling height,leaf area,leaf width,and fresh weight of aboveground parts increased by 80.63%,113.69%,50.99%,and 50.72%,respectively.（7）Compared with the control group,the plant height,leaf area,leaf width,and fresh weight of aboveground parts of cucumber seedlings in the Na₂CO₃group decreased by38.11%,41.25%,31.42%,and 27.56%,respectively;compared with the Na₂CO₃group in the NYJ+Na₂CO₃group,Seedling height,leaf area,leaf width,and fresh weight above ground increased by 68.12%,42.68%,56.71%,and 52.49%,respectively.（8）Compared with the control group,the plant height,leaf area,leaf width,and fresh weight of aboveground parts of cucumber seedlings in the NaCl group decreased by 47.71%,58.09%,40.64%,and 66.09%,respectively;compared with the NaCl group,the cucumbers The root length and stem length and fresh weight of seeds increased by 12.63%,90.56%,41.74%and 106%respectively.（9）This experiment measured the enzyme activity of cucumber rhizosphere soil in eight different treatment groups under three salt stresses.Compared with the control group,the activities of urease,phosphatase catalase and sucrase in Na₂SO₄group were reduced 59.06%,19.63%,26.98%and 25.31%;compared with Na₂SO₄group,NYJ+Na₂SO₄group increased urease,phosphatase,catalase and sucrase by 175%,38.68%,31.88%and 73.43%respectively.The activities of urease,phosphatase,catalase and sucrase in the Na₂CO₃group decreased by35.68%,47.27%,25.83%and 29.95%,respectively;compared with the Na₂CO₃group in the NYJ+Na₂CO₃group,urease,phosphatase,catalase and sucrose Enzymes were increased by15.23%,72.31%,34.1%and 53.59%,respectively.The activities of urease,phosphatase,catalase and sucrase in the NaCl group were reduced by 80.18%,49.23%,36.78%and21.04%,respectively;compared with the NaCl group in the NYJ+NaCl group,urease,phosphatase,catalase and sucrose Enzyme activity increased by 1164%,17.3%,41.48%and88.49%respectively.（10）In this experiment,16Sr DNA high-throughput sequencing technology analysis was performed on eight different treatment groups of cucumber rhizosphere soil under three different salt stresses.The analysis results showed that Na₂SO₄stress,Na₂CO₃stress and NaCl stress all affected soil microbial diversity And the community structure,indicating that the three salt stresses will seriously inhibit the growth of cucumber and change the soil environment;compared with the three different salt stress groups,the NYJ+Na₂SO₄treatment group,NYJ+Na₂CO₃treatment group and NYJ+NaCl treatment group are all Significantly improved soil microbial diversity and community structure,indicating that NYJ strains can effectively alleviate the damage caused by salt stress to plants,and can effectively improve the soil microenvironment.