耐盐碱解磷菌的溶磷效果及其对黄豆萌发的影响

Phosphorus solubilization effect of saline-tolerant phosphorus-solubilizing bacteria and its effect on soybean germination

摘要:

【背景】土壤中能够供植物直接吸收利用的磷含量较少，而传统施用磷肥的方式会导致环境污染，并破环土壤结构和功能等问题。【目的】研究巨大芽孢杆菌(Bacillus megaterium)和雷氏普罗威登斯菌(Providencia rettgeri)的耐盐性、溶磷机制及其对黄豆种子萌发的影响，为植物根际盐碱土壤接种定殖及促生效果奠定坚实的基础，以期通过根际土壤解磷菌的解磷作用来解决作物缺磷问题。【方法】结合接种针点接法、平板法、液体培养法及发芽盒发芽等试验，剖析了2株解磷菌的耐盐碱性、溶磷效果及其对黄豆萌发的促进效应。【结果】巨大芽孢杆菌和雷氏普罗威登斯菌分别在盐浓度为0−10%、0−6%的范围及pH值为7.0−12.0的环境下均可以生长；巨大芽孢杆菌和雷氏普罗威登斯菌在平板上的D/d值分别达到2.17和2.05，第4天于液体培养基中溶磷量达到峰值，分别为355.53 mg/L和272.17 mg/L，培养介质pH值由7.5分别降至4.61和4.81。巨大芽孢杆菌和雷氏普罗威登斯菌溶磷效果随NaCl浓度的增大均呈现“先略增强后持续减弱”的趋势，pH值均呈现“先略减小后持续增大”的趋势，NaCl浓度分别为0.4 mol/L和0.2 mol/L时溶磷效果最好，溶磷量达到峰值364.35 mg/L和285.58 mg/L，培养介质的pH值降至最小值4.28和4.73。巨大芽孢杆菌和雷氏普罗威登斯菌对种子发芽率及胚轴、胚根的伸长均有提高，在正常环境和NaCl处理环境下，与对照组相比，经2种菌液浸泡后黄豆的平均发芽率、胚轴及胚根平均增长率分别为2.70%、10.10%、9.00%和5.40%、19.40%、20.30%。【结论】2株菌均具有较强的耐盐性和溶磷效果，能促进种子萌发，可以进一步为解磷菌的接种及应用提供理论依据。

Abstract:

[Background] The amount of phosphorus available for direct absorption and utilization by plants in the soil is limited, and the traditional methods of applying phosphorus fertilizer can lead to environmental pollution and problems such as damage to soil structure and function. [Objective] This study aimed to investigate the salt tolerance and phosphorus solubilization mechanism of Bacillus megaterium and Providencia rettgeri and their effects on soybean seed germination, to lay a solid foundation for inoculation and colonization of plant rhizosphere in saline-alkali soil. The problem of phosphorus deficiency in crops is expected to be solved through the phosphorus-solubilization effect of phosphorus-solubilizing bacteria in rhizosphere soil. [Methods] The inoculation with needlepoint, plate method, liquid culture method, and box germination experiment were conducted to analyze the salt-alkali tolerance, phosphorus-solubilization effect, and promotion effect on soybean germination of two phosphorus-solubilizing bacteria strains. [Results] Both B. megaterium and P. rettgeri could grow in environments with salt concentrations ranging from 0−10% and 0−6%, and pH values ranging from 7.0 to 12.0. The D/d values of B. megaterium and P. rettgeri on plates reached 2.17 and 2.05, respectively. The value of dissolved phosphorus in the liquid medium reached a peak on the 4th day, which were 355.53 and 272.17 mg/L, respectively, and the pH value of the culture medium decreased from 7.5 to 4.61 and 4.81, respectively. The phosphorus solubilization effect of B. megaterium and P. rettgeri showed a trend of “slightly increasing at first and then continuously decreasing” with the increase of NaCl concentration, and the pH value showed a trend of “slightly decreasing at first and then continuously increasing”. The best phosphorus solubilization effects were observed at NaCl concentrations of 0.4 and 0.2 mol/L, respectively, with the peak solubilization value of 364.35 and 285.58 mg/L, and the pH value of the culture medium decreased to the minimum value of 4.28 and 4.73, respectively. B. megaterium and P. rettgeri both increased the germination rate of seeds and elongation of the embryonic axis and radicle. Compared with the control group, in normal environments, the average germination rate, and the embryonic axis and radicle elongation rate of soybeans after soaking in the two bacterial solutions were 2.70%, 10.10% and 9.00%; in NaCl-treated environments, the corresponding value were 5.40%, 19.40% and 20.30%. [Conclusion] Both strains have strong salt tolerance and phosphorus solubilization effect and can promote seed germination, providing a theoretical basis for the inoculation and application of phosphorus-solubilizing bacteria.