BACKGROUND Excessive application of chemical fertilizer has exerted a great threat to soil quality and the environment. The inoculation of plants with plant-growth-promoting rhizobacteria (PGPR) has emerged as a great prospect for ecosystem recovery. The aim of this work to isolate PGPRs and highlights the effect of bacterial inoculants on available N/P/K content in soil and on the growth of wheat under conditions of reduced fertilizer application. RESULTS Thirty-nine PGPRs were isolated and tested for their growth-promoting potential. Thirteen isolates had nitrogen fixation ability, of which N9 (Azotobacter chroococcum) had the highest acetylene reduction activity of 156.26 nmol/gh. Eleven isolates had efficient phosphate solubilizing ability, of which P5 (Klebsiella variicola) released the most available phosphorus in liquid medium (231.68 mg/L). Fifteen isolates had efficient potassium solubilizing ability, of which K13 (Rhizobium larrymoorei) released the most available potassium in liquid medium (224.66 mg/L). In culture medium supplemented with tryptophan, P9 (Klebsiella pneumoniae) produced the greatest amount of IAA. Inoculation with the bacterial combination K14 + 176 + P9 + N8 + P5 increased the alkali-hydrolysed nitrogen, available phosphorus and available potassium in the soil by 49.46, 99.51 and 19.38%, respectively, and enhanced the N, P, and K content of wheat by 97.7, 96.4 and 42.1%, respectively. Moreover, reducing fertilizer application by 25% did not decrease the available nitrogen, phosphorus, and potassium in the soil and N/P/K content, plant height, and dry weight of wheat. CONCLUSIONS The bacterial combination K14 + 176 + P9 + N8 + P5 is superior candidates for biofertilizers that may reduce chemical fertilizer application without influencing the normal growth of wheat.

中文翻译：

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在减少肥料用量的情况下，有益细菌可以活化营养并促进小麦生长。

背景技术化肥的过量施用对土壤质量和环境构成了巨大的威胁。用促进植物生长的根际细菌（PGPR）接种植物已成为生态系统恢复的广阔前景。这项工作的目的是分离PGPR，并强调了细菌接种剂对减少肥料施用条件下土壤中有效N / P / K含量和小麦生长的影响。结果分离出39个PGPR，并测试了其促进生长的潜力。十三株分离株具有固氮能力，其中N9（绿脓杆菌）的最高乙炔还原活性为156.26 nmol / gh。11种分离物具有有效的磷酸盐增溶能力，其中P5（水溶克雷伯菌）在液体培养基中释放的磷最多（231）。68 mg / L）。15个分离株具有有效的钾增溶能力，其中K13（拉里根瘤菌）在液体培养基中释放的钾离子最多（224.66 mg / L）。在补充了色氨酸的培养基中，P9（肺炎克雷伯菌）产生了最多的IAA。细菌组合K14 + 176 + P9 + N8 + P5的接种分别使土壤中碱解氮，有效磷和有效钾分别增加49.46％，99.51和19.38％，并提高了土壤中的氮，磷和钾含量。小麦分别增长97.7％，96.4和42.1％。此外，减少肥料用量25％不会减少土壤中的有效氮，磷和钾，以及N / P / K含量，株高和小麦干重。