酸性土壤中接种耐酸根瘤菌对豆科植物根际微生态的影响

任豫霜; 朱丹; 姜伟; 李玖燃; 张磊

doi:10.11674/zwyf.16362

酸性土壤中接种耐酸根瘤菌对豆科植物根际微生态的影响

Effect of inoculating aciduric rhizobia on rhizospheric microecology of the leguminous hosts in acid soil

摘要

摘要:
目的接种耐酸豆科根瘤菌可以提高豆科植物耐酸能力。应用PLFA等方法研究接种耐酸根瘤菌对根际土壤微生态的综合影响，从土壤角度阐明接种耐酸根瘤菌缓解土壤酸度对豆科植物胁迫的机制。
方法盆栽条件下分别向种植于pH 4.8酸性土壤中的葛藤和苜蓿植株相应接种耐酸葛藤根瘤菌068、389、390与耐酸苜蓿根瘤菌91512、91522、91532，于接种后30 d、60 d、90 d、120 d、150 d取样，分析耐酸根瘤菌对土壤养分、可培养微生物、微生物群落结构多样性的影响。
结果1) 接种耐酸葛藤和苜蓿根瘤菌处理后，根际土壤pH由4.8显著提高至6.0左右，有效磷、速效钾、铵态氮、硝态氮及有机质含量的增加效果显著 (P < 0.05)，至120 d 达到最高。120 d样品的有效磷、铵态氮、硝态氮及有机质含量分别为23.16～48.68 mg/kg、61.21～81.96 mg/kg、65.05～86.38 mg/kg和11.85～12.87 g/kg，分别比未接种对照提高24.8%～162.4%、16.6%～56.2%、145.4%～225.8%、1.4%～10.1%；2) 接种苜蓿和葛藤耐酸根瘤菌后土壤中可培养微生物数量显著提高 (P < 0.05)，土壤中可培养细菌、真菌和放线菌数量在120 d达到峰值，比同期未接种对照分别提高了61.5%～348.4%、3.4%～441.7%和18.9%～255.2%，分别达到48.00 × 10²～133.3 × 10⁷、20.11 × 10⁴～155.9 × 10⁴和3.21 × 10⁴～9.59 × 10⁴ cfu/g鲜土；3) PLFA分析表明，虽然接种耐酸葛藤、苜蓿根瘤菌处理的根际土壤的特征脂肪酸种类数与未接种处理相比并无明显差异，但接种葛藤或苜蓿根瘤菌均明显降低了根际土壤中异构PLFA/反异构PLFA值，显示土壤根际微生态的稳定性得到提高。
结论在种植豆科植物的酸性土壤中接种相应耐酸根瘤菌能显著提高根际土壤pH，提高根际土壤有机质含量和速效氮磷养分含量，缓解土壤酸性对根际微生物的胁迫。

Abstract:
ObjectivesExisting studies proved that inoculating aciduric rhizobium to the rhizosphere could improve the ability of leguminous host to survive in acid soils. In this paper, the PLFA and other methods were used to study the effect of inoculating rhizobium on rhizospheric soil in order to understand the mechanism of the improvement.
MethodsA pot experiment was conducted using acid soil of pH 4.8. Aciduric kudzu rhizobium strains 068, 389, and 390 and alfalfa rhizobium strains 91522, 91512 and 91532 were inoculated to the corresponding leguminous host plants. Rhizospheric soil samples were collected on the 30^th, 60^th, 90^th, 120^th and 150^th day after the inoculation. Soil nutrients, culturable microorganisms and microbial community diversity were measured in the samples.
Results1) Inoculating acid-tolerant rhizobia improved rhizospheric soil pH from 4.8 to 6.0, significantly improved the contents of soil organic matter, NH₄⁺-N, NO₃^–-N, available P and available K in rhizosphere (P < 0.05). The peak contents of soil available P, NH₄⁺-N, NO₃^–-N and organic matter in the inoculating treatments were at the 120^th d, they were 23.16–48.68 mg/kg, 61.21–81.96 mg/kg, 65.05–86.38 mg/kg and 11.85–12.87 g/kg, with increase of 24.8%–162.4%, 16.6%–56.2%, 145.4%–225.8%, 1.4%–10.1%, comparing with those of the control. 2) The population of soil microorganisms increased significantly during the cultural period (P < 0.05). The peak microbial community appeared at the 120^th d samples, the culturable bacteria, fungi and actinomycetes in the treatments were 48.00 × 10⁷–133.3 × 10⁷ cfu/g, 20.11 × 10⁴–155.9 × 10⁴ cfu/g, and 3.21 × 10⁴–9.59 × 10⁴ cfu/g, increased by 61.5% to 348.4%, 3.4% to 441.7%, 18.9% to 255.2% respectively, comparing with those of the control. 3) PLFA analysis showed that although the types of microbial PLFAs in rhizospheric soil were not significantly different between the inoculation treatments and the control, the ratio of heterogeneous PLFA/anti heterogeneous PLFA was reduced significantly, showing effective reduction of acid stress on rhizosphere microorganisms.
ConclusionsInoculating the related aciduric rhizobium strains to the leguminous hosts planted in acid soil could improve the rhizospheric soil pH, organic matter, and available nutrients significantly, and hence improve the ability of rhizopheric micro-organisms to deal with soil acidity stress.

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